Q 4cr- - SAU Institutional Repository

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IIETEROSIS AND ITS ASSOCIATION WITH GENETIC ATTRIBUTES USING LINE X TESTER MATING IN RICE (Or,'za saliva L.)

By

MD. KAMAL 1-JOSSAIN REGISTRATION NO.: 07-02621

A Thesis

Submitted to the Faculty of Agriculture Sher-e-Bangla Agricultural University, Dhaka

in partial fulfillment of the requirements for the degree of

MASTER OF SCIENCE IN

GENETICS AND PLANT BREEDING SEMESTER: JULY - DECEMBER-2008

Approved by

Q 4cr-

(Dr. A %V Julliquar)

Director (Admit,. & Common Service) BRRI, Gazipur

Supervisor

(Dr. Md. Sarowar Hossain) Professor

Co-supervisor

(Dr. iIalinud) Chairman

Examination Committee

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'tGiICIt't tM iciidR

_j Bangladesh Rice Research Institute, Gazipur

Fax: 9252734, Telephone: PABX - 9257401-5.

Email:

kwlunU?

11Jinecn 1

aEVI'FICft9YE

is to certify that the thesis entitk, 1

9fflsqtqosis

AND ITS fiSSOCIfiTIOTI W1W çETv7fl7c flIV'BVES

'Usiwg

LIWtE X flSFEc& WA qTqVG 15V cRJOE (Oryza sati'va £) submitted to the 'TFaculTty of figriculiure, SIzer-e-'Bangfiz Jlgricuüuraf t),üverS tvhakg in partia(fv[fiffment of the requirements for the degree of WTSIT'Eck OF

scicEAwcE

in gw17v!E'flcS

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^q)Jy? tflhEWIWg embodies the resuft of a piece of bonafidè research work carnal out by SM(D. ICItMAL %OSSJ4I9V,' cRjgthtration Wo. 02621 under my supervision andT guidance. 5Vb part of the thesis has been submitteifor any oilier tfegreeordiploma.

IJitrt her certify that such help or source of information, as has been availed of Luring the course of this investigation has Lizlj been aci€jwwlè4et

Date& (December, 2008 D&ce: gazipur,BangThAesh

f/fl

(a'r. A Wyu(flquar)

(Director (Admin. (t Common Service) BVtj, gazipur

Supervisor

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DEDICATED TO

THE ALMIGHTY ALLAH WHO CREATED

THE UNIVERSE

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A flçyvoWJyEqLgcE,s41(EwTs

'First

of

ag the author qffers his most humble gratitude to X9uIqJfFYALLfrIi who createt the universe and best otuet the manIjnJwu1i fij:owlefije ant wistom to search the secrets. I earnestly bow before Ms Compassionate 'Endinvmen.t 'Who enable me to complete this piece of thesis successfidly.

The ant lwr expresset his teepest gratitute ant! profounil regart with a great pleasure ant privilege to his reverezul supervisor cDr. ii. 'W julfiquar, (Project Director, LH3'b:ii Rjce Project and Director (Alifinin.), Banglatesh 'Rice 'l4searcfl Institute, gazipur for his va/liable guitance and constant encouragement and close supervision dl:d::g the periot

of

his research and in preparation

of

^this

manuscnpt.

die author woult liiq to express his great pleasure antteep sense

of

gratitute to his co-supervisor Prof :br, Mt Sarowar :Kossain, (Department

of

qenetks and Plant (Breeding, Siier-e-']Jangla Jigricuilural 'University. S/i er-e-(Bangla Wagar, DflaIg for scholastic ant unfailing guitence instruction ant helpful turing his course of stuty ant research in preparation of this manuscript.

The ant/icrwoult also liiic to express sincere t/ian&c to his teacher Dr. Firoz !Mahmud Chairman,

®epartment of qenetics and Plant (Breeding, S/ier-e43ang(a Agricultural t1niversity, 'Vfla&a for encouragement ant inspiration in preparation of this manuscript.

i/ic author isgratejlilto a//his respectet teachers of the Vepartinent of qenetics antPlant (Breeding, Sher-c-Q3angla ./Igricultural 'University, Dfiaq for their kfnt cooperation ant assistance dlsnizg the

course ofstuty.

qlie author sincere to express his respect ant gratitute to the authority of Wanglatesh ice 'i4search Inst it ute'(B RSRj) for awarding ant granting him to leave of absence on teputation to pursue an 21.5.

tegree at She r-e-(Bangla Jigricuft ural 'University, cDfla&a.

The author e.iencfs special t/iaz:fj to jinowara )l/jjer, Scientfic Officer, 1w. Zamil J{asan., Senior Scicnt!fr Officer, and Dr. MC! 2/az rat )IIt ThncipalScientflc Officer, J(ybnkl 'Rfrc (Project, i3ai:gla4fesh Rfrc 'I<csearc/; institute, çazipur for their cvjenti::g fifnt cooperation dànng the whole cq;erñnent contact ing at W}bncl'Rjce Qtesearcfl plot, B'RRJ.

711e author express his inunense grat it ate to the personnel wor&ing in the Yrybrid 'Rjce 'Project in W'RRJ for their trementous help in contuct ing the experiments.

'The author express his heartfelt gratitute to his parents aud family members for their blessing, encouragement antconstant inspiration in the pursuit qf his higher stuty.

'Finally, the ant her than/i; to all his colleagues, Jrients and well wis he rs for their goot wishes all the time.

:DaredT 'Decerriber, 2008 'T/iefluthor

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SYMBOLS AND ABBRE'LATIONS

ABBREVIATION ELABORATION

ANOVA URR1 BP 13 H P cm CMS Cv DAT d f

I,

OCA. gca i.e.

I R.R1 IFPR1

MP M P1!

MSF., Me MSS RC Br) SCA. sea SE SEd Si' Ss 1 V

%

= Analysis ol variance

= Bangladesh Rice Research Institute

= Better patent

Better patent heterosis

= Centimeter

= Cytoplasniic-genetic male sterile

= Coefficient of variation

= Days after transplanting

= Degree of freedom

= First filial generation

= Gram

= General combining ability

= That is

= International Rice Research institute

International Food Policy Research Institute

= Line

= Mid parent

= Mid parent heterosis

= Standard error of mean

= Mean sun of square

= Randomized complete block design

= Specific combining ability

= Standard error

= Standard error of difference

= Standard heterosis - Sum of squares

= Tester

= summation

= Square root

= At the Tate of

= Per eentage

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LIST OF TABLES

IAI3LE NO. - TITLE PAGE NO.

List of parental lines with their brielintroduction 29 2 Analysis of variances of 14 agronomic and yield 49

related traits

3

Proportional contribution of line (CMS), tester 51 (Restorer) and their interaction (Line x Tester)

4 Mean performance of parents and crosses

53-54

5 Ciencral combining ability (GCA) effects of parents 56

14 agronomic and yield related traits

6 Specific combining ability (SCA) effects of parents

58-59

14 agrononiic and yield related traits

7 Distribution of crosses in relation to GCA effect of 61 parents and SCA of crosses for 14 agronomic and

yield related traits

8 Extent of heterosis over mid parent (MPH), better 79-83 parent (BPH) and standard check varieties (SF1) for

different agronomic and yield related characters

9 Correlation coefficient (r) between GCA and per se 103 performance of parent and SCA and cross mean for

agronomic and yield related traits

10 Correlation coefficient (r) between heterosis (over 105 mid parent and better parent) and specific combining

ability (SCA) effects of crosses for 14 agrononiic and yield related traits

II Heterosis over mid parent (in desirable direction) in 108 relation to GCA for 14 agronomic and yield related

traits

12 Heterosis over better parent (in desirable direction) in 109 relation to GCA for 14 agronomic and yield related

traits

IV

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LIST OF FIGURE

PLATE

NO. TITLE PACE

NO.

I Phenotypic diversity of parents (P1-P6) 30 2 Phenotypic diversity of parents (P7-P12) 31 3 Phenotypic diversity of parents and Checks (P 13, Cl, C2) 32 4 Agronomic performance of Fl hybrids (H 1-1-18) 85 5 Agronomic performance of El hybrids (H9-H16) 86 6 Agronomic performance ofFi hybrids (I417-H24) 87 7 Agronomic performance ofFi hybrids (I-i25-H32) 88 8 Agronomic performance of Fl hybrids (H33-H40) 89

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LIST OF PLATES

PLATE NO. TITLE PACE NO.

Crossing block of parental line 33

2 Spikelet clipping for facilitation of pollination 33

3 Collection of male flower 34

4 Artificial pollination for hybridization 34

5 Mass of hybridized and bagged plant 35

6 Hybridized plant bearing F1 seeds 35

7 An over-view of evaluation plot 84

8 Heterotic diversity ofF1 hybrids 84

9 Author recording data in the field 119

10 Author recording data in the lab 119

VI

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HETEROSIS AND ITS ASSOCIATION WITH GENETIC ATTRIBUTES USING LINE X TESTER MATING IN RICE (Oryza saliva IA.)

BY

MD. ICANIAL HOSSAIN

ABSTRACT

An investigation was carried out to assess the combining ability effects. heteroses from parent.,;

and their hybrids during November. 2007 to November. 2008 at Bangladesh Rice research Institute (BRRI). Gazipur. The analysis of variances were carried oul for 14 agronomic and yield related characters indicated that the genotypes were differed significantly From each other for all the characters studied. Combining ability studies revealed that the specific combining ability (SCA) effects were higher that and general combining ability (GCA) effect for most of the traits except panicle length. primary branch panicle4, spikelet panicle-1 and spikelet fertility which indicated that importance of both additive and non-additive gene actions were governing the inheritance on the coneerncd traits but the non-additive gene action were prcdominant. Among the CMS lines BRRI3A produced significant and desirable OCA effects for shorter plant height.

earliness, tiller hill', panicle length (cm) and number of tmicles mete(2 which was considered as a good general combiner for these traits concerned. Similarly, the restorer BRRII2R identi fled as the best general combiner for shorter plant height, earliness and number tiller hill' and the an other restorer line I3RRI I 7R selected as the best general combiner due to their desirable and significant (WA effects for spikelet fertility (%) 1000-grain weight and yield plant". Result indicated that the hybrid combinations 1R73328A113R736. 1132A/BR736R. BRRI I 0Afi3R6723-i - 1-2k and 1132A1BR6839-41-5-IR were found as the best specific combiner for yield plant-'.

spikelet fertility (%) and 1000-grain weight for their highly significant and positive SCA values.

Ihe combinations IJRRI3A/I3RRI I 7R. 1R73328A/BR6723- I-I -2R, BRRI9A/BR6839-41 -5-I R 13RR1 1 OA/RRI 68R and 1132A/BR827R were also identified as good specific combiner for shorter plant height and earliness due to their significant and negative SCA effects. On the other hand. the hybrids: BRRI3A/13RRJ 12R. BRRI3A/BRRI I 7R. I3RRI9eVBRRII OR. BRRI9A'BRRI 12R and I3RRI9AJBRRII7R manifested significant and desirable heterosis over mid parent. better parent and over standard checks For grain yield plant'. 1000-grain weight, plant height, days to 50%

flowering and days to maturity, therefore, these hybrids combinations were selected as the best performer among the combinations evaluated in this study. Considering the character association studies, it was observed that out of 227 significant and desirable SCA effects 69 were produced by High x Low OCA parental conibination, where as the maximum number of heterotic crosses were evolved from I-ugh x Average OCA parental combination for both mid-parent and better parent heterosis.

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CHAPTER I

INTRODUCTION

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CHAPTER 1

INTRODUCTION

Rice is the most important cereal crop of the world including Bangladesh.

More than 50% of the world population consumes rice as a staple food. Rice provides about four-fifth of the calories for more than two billion people of Asia and one-third of the calories for nearly one billion people in Africa and Latin America (IFPRI, 1977). Moreover, the population of rice consuming countries is increasing faster than that of the rest part of the world and the number of rice eaters will probably he double in the next 30 years with present level of consumption.

Bangladesh is the forth largest producer and consumer of rice in the world with an annual production ranging from 25 to 30 million tons. Rice occupies 77% of total cropped area. At present, rice alone constitutes about 92% of the total food grains produced annually in the countiy. It provides 75% of the calories and 55% of the proteins in the average daily diet of the people (Bhuiyan

et at,

2002). Compared with mid-sixties, Bangladesh has almost doubled its production during the past three decades and the higher rate of production mainly came from reallocation of land from traditional to the high yielding modern varieties. A modest estimate suggests that the demand for rice in Bangladesh will have to increase by over 80% in the next 20 years to feed the growing population (Zaman, 1996). Further estimate is rather more precise to feed the population by the year 2025, which is about 21% higher than the production of 2000 (Bhuiyan

et at.

2002). To produce the required quantity, the only option remains open is the increase production per unit area, as there is scarcity of land.

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Semi-dwarf high yielding modem varieties though has increased yield dramatically in many rice- growing countries; yield plateaus have been reached in many rice-growing regions. Such a situation, hybrids oiler to break through the yield ceilings of semi-dwarf rice began in 1964. China is the first country to commercially exploit heterosis in rice. The discovery of CMS in rice (Athwal and Virmani, 1972) suggested that breeding could develop a commercially viable F1 hybrid. The most promising hybrids yielded 20-30% (Lin and Yuan, 1980) and 15-20% (Yuan, 1998) higher than the best conventional rice varieties, respectively.

Dramatic yield improvement in semi-dwarf rice varieties achieved during past few decades was possible due to improvement of physiological traits though more attention was paid for the improvement of morphological traits.

A substantial increase (20-30%) in yield is possible through selective improvement of major yield components (Siddiq, 1993).

Combining ability is one of the powerthl tools in identifying the best combiners that may be used in crosses either to exploit heterosis or to accumulate fix genes. To exploit heterosis using CMS technique in the hybrid pro2rammc, one must know the combining ability of different male sterile and restorer lines. It helps to know the genetic architecture of various characters that enable the breeder to design effective breeding plan for friture up-gradation of the existing materials. The information is also useful to breeders for genetic improvement of the existing rice genotypes on the basis of the performance in various hybrid combinations.

Since, the information on heterotic effect of F1 hybrids, their genetic control and combining ability are very much limited in rice, a comprehensive study was undertaken on the basis of different agronomic and morphological characters with the following objectives:

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To assess the combining ability of selected parents and their hybrids To estimate the nature of gene action and magnitude of heterosis; and To find out relationship between combining ability and heterosis of parents and their hybrids.

To find out promising parental (CMS and restorer) lines and heterotic

hybrid combination(s).

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CHAPTER II

REVIEW OF LITERATURE

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CHAPTER II

REVIEW OF LITERATURI

2.1 Combining ability

The concept of combining ability was put forward by Sprague and Tatum (1942) using single cross of maize. They defined the term general combining ability (OCA) as the average performance of a line in a series of hybrid combinations. Specific combining ability (SCA) was used to designate dose effects in certain combinations, which significantly departed from what would be expected on the basis of average performance of the lines involved.

Combining ability analysis is a powerful tool to discriminate the good as well as poor combiners for choosing appropriate parental material in plant breeding programme in eiop plants. The per se performance of parent may not necessarily reveal it to be a good or poor combiner. Therefore, gathering information on nature of gene effects and their expression in terms of combining ability is necessary. At the same time, it also elucidates the nature of gene action involved in inheritance on characters. General combining ability is attributed to additive effects and additive x additive epistatis and is theoretically fixable. On the other hand, specific combining ability attributable to non-additive gene action may be due to dominance or epistatis or both and is non fixable. The presence of' non- additive genetic is the prinian' justification for initiating the hybrid programme (Cockerharn, 1961).

Various methods have been developed for the estimation of combining ability, of which inbred-variety cross of top-cross, poly cross, diallel, partial diallel, triallel and line x tester analyses are worth mentioning. In the present investigation, line x tester analysis has been used for estimating the GCA and SCA variances and effects and genetic component of variances (&A and

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2D). Line x Tester is a modified and improved method over top-cross method is somewhat similar to North Caroline Design (NCD-I1) of Comstock and Robinson (1952). In this method, a random sample of lines (L) will be crossed to each of the selected testers (T) for assessing the genetic attribute of the parents and hybrids by estimating the GCA of the parents and SCA of the hybrids. respectively (Kernpthrone, 1957).

In rice, many scientists studied the nature of combining ability of parents and hybrids for different traits.

Zhou et al. (1982) in an uncompleted diallel cross of six male sterile lines and five restorers reported that the GCA was more important than SCA in most cases. In the hybrids, each character was influenced by the GCA of both male sterile line and restorer line and also by the SCA of the combination together designated as "total combining ability".

Amrithadevarathinam (1983) made a combining ability analysis in rice through Line x Tester analysis for yield and major yield components and observed considerable degree of genetic variability in the parents. The combining ability variances were significant and indicated the importance of both additive and non-additive gene actions in the expression of yield characters.

Dzyuba and Baracy (1983) considered the combining ability as the criterion in selecting parents of Soviet rice hybrids by top crosses, using three testers with unclear male sterile and 10 best lines. High SCA for grain weight and number of spikelets were shown by three pollen parents.

Ravikurner (1983) studied combining ability for yield and eight yield related characters. In crosses of three CMS lines and 22 inbred lines in a Line x

D

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Tester fashion. Combining ability estimates indicated the importance of both additive and non-additive gene actions in the control of characters.

Shrivastava and Sheshu (1983) reported that GCA variances were significant for yield and 15 related characters whereas SCA variances were significant for only 12 characters. GCA was of more significant than SCA for most traits, while SCA was more important for grain yield/plant and panicle length.

Anandakurnar and Rangasamy (1984) estimated GCA and SCA in rice using eight dwarf and two tall varieties in a Line x Tester analysis and reported significant variances for both GCA and SCA for all the four characters studied. Variance due to SCA for plant height, paniele length and yield/plant indicated the predominance of non-additive gene action.

Thendapani (1986) in a L x I analysis for 12 quantitative characters using seven induced semi-dwarf mutants as lines and three tall as testers, observed both additive and non-additive gene action for yield traits. Among the parents, only five were found to be the best general combiners. Manifestation of high lieterosis for yield and dry matter production was noticed in the hybrids ofCo29DiFN 1 , and TKM6/1R50 with or without SCA effects.

Koh (1987) studied combining ability of F, hybrids using 4 CMS and 5 restorer lines. All the hybrids showed highly significant SCA effects for yield related characters.

Sharma et al. (1987) evaluated 30 cross combination for hai-vest index (HI) and component characters in a L x T analysis. Considerable variation was observed for all IG characters in F1 s and parents. Combining ability analysis showed both additive and non-additive types of gene actions playing

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significant role in controlling the expression of all the characters under study.

The exception was economic yield for which only non-additive gene action was found to be significant.

Combining ability for eight characters studied by Wang and Tang (1988) indicated that panicle number/plant was mainly affected by GCA effects of A lines and grain yield/plant was unaffected by GCA of R lines. GCA effects of A and R lines played a more important role than SCA effects. The results indicated a very close and consistent positive relationship between heterosis and combining ability implying that the heterosis of a hybrid combination could be predicted reliably by combining ability.

Manuel and Palanisamy (1989) studied CA through L x 'F analysis involving 5 lines and 3 testers for 9 characters. They observed that all the 9 characters were governed by additive and non-additive gene actions except panicles/plant. The ratio of GCA and SCA variances revealed the importance of additive gene action for days to tiowering, plant height and panicles/plant and the predominance of non-additive gene action for the others.

Peng and Virmani (1990) calTied out combining ability analysis for grain yield and other related characters using L x •F analysis involving 7 maintainer and II restorer lines. They found that GCA and SCA variances were signilicant for yield, thy matter, days to flowering and plant height.

l.okaprakash (1990) in his investigation with 21 hybrids, observed predominance of additive gene action for plant height and non-additive gene action for panicles/plant. panicle length, fertile spikelet/panicle, straw weight, grain yield and harvest index.

Peng and Virniani (1990) reported from the combining ability study for grain

VA

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yield, dry matter, harvest index, plant height and days to flower using line x tester analysis involving 11 maintainer and restorer lines. General combining ability (GCA) and specific combining ability (SCA) variances were significant for yield, dry matter, days to flowering and plant height. For harvest index, only SCA variance was significant, implying that the first four traits are controlled by both additive and dominant gene actions. The harvest index, however, is primarily controlled only by dominant gene action.

Significant GCA effects for the five traits were observed in the parents and good general combiners for each of the characters could be identified. High GCA effect for yield of a specific line was found associated with high GCA effect for dry matter production or harvest index (HI). Parental lines possessing significantly high GCA effects for both dry matter and HI were not available among those included in the study. High GCA effects for yield mostly were associated with high GCA effect for plant height and days to flowering.

Mishra ci a/. (1991) studied the GCA of IS parents and the SCA of 45 crosses in a I 5L x 3Tmating design. The best general combiners for grain yield were 1ET5656, Narendra 80, 11154, Z97A and T2 I. Only seven crosses showed high SCA effects for one or more characters. The cross combination showing high SCA effect for grain yield also showed high SCA effect for tiller number indicating tiller number is an important yield component.

Tongmin and Luxinggui (1991) analyzed combining ability of 30 F1 hybrids through 5L x 6T mating pattern for grain yield/plant and 10 other agronomic traits. GCA and SCA variances were significant for all traits, indicating that additive and non-additive interactions were important. Variances due to SCA were greater than those due to GCA for grain yield/plant and fertile spikeletlpanicle, suggesting dominant gene action. Variances due to GCA were greater than those due to SCA for other traits.

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Banumathy and Prasad (1991) studied with 12 rice hybrids involving four CMS lines and three testers and analyzed for their combining ability fbi the quantitative traits. The SCA variance was higher than the GCA variance (hr plant height, number of filled grains, percentage of spikelets and grain yield/plant, indicating the prevalence of non-additive gene action was fhund to be important for number of productive tillers and length of the panicle.

Among the parents evaluated, 1R62829A was found to be a good general combiner for grain yield, plant height and number of filled grains. The cross 1R62829A x 11(50 expressed high positive significant SCA effect for plant height.

Manuel and Prasad (1992) studied with five lines, three testers and their 15 hybrids for their combining ability and heterosis on four characters viz, grain yield/plant, straw yield/Plant, dry matter production and harvest index.

Importance of additive gene action for straw yield/plant, and both additive and non-additive gene actions for other traits were brought out. Parents ASI)16 and 11(50 were the best general combiners for grain yield, straw yield and dry matter production; and their hybrid combination (ASD15 x 1R50) recorded the highest SCA effects for the above three traits as well as harvest index. Yield superiority of heterotic F1 was attributed to increase dry matter production.

Chauhan and Chauhan (1993) reported that flag leaf angle seemed to be predominantly under additive gene effects as suggested by lack of heterosis and heterobeltiosis in most of the crosses.

Bobby and Nadarajan (1993) reported that SCA variances were greater than the (JCA variances for the traits; days to 50% flowering, plant height, productive tillers, boot leaf area, panicle exertion, panicle length, productive tillers, boot leaf area, panicle exertion, panicle length, grains/panicle, 100-

9

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grain weight and grain yield. The results indicated the predominance of non- additive gene action for these traits.

Ramalingan) et cii. (1993) observed four general combiner parents and six specific combiner crosses of lowland rice for major yield and yield attributes through L x T analysis, and reported a preponderance of non-additive over additive gene action for all the yield contributing character including flag leaf angle except 100-grain weight. The superior cross combinations were obtained from high x high, high x low and low x low general combiners.

High positive and significant association was obtained between per se performance and GCA effects of the parents.

Lang and Butt (1993) reported, in the study with some morpho-physiological traits, that high significant mean squares of all traits for both general combining ability (GCA) and specific combining ability (SCA) indicated the importance of both additive and non-additive gene action. 1-lowever they also reported that SCA variance were higher than the GCA variances, suggesting the prevalence of non-additive gene effects for CGR, NAR, HDI, HI and grain yield. They also reported that 0M80 appeared to be the best combiner for yield; 1R46, 0M80. 1R68 and 0M86 for LA! at heading, 11(36 for NAR (panicle initiation to heading); 0M201 for NAR (heading to harvest); IRS, 1R36 and 1R46 for CGR (panicle initiation to heading); and lR36, 1R42 and 0M201 for I-Il.

Chen et at (1995) reported highly significant GCA effects in all the parents for grain yield/plant and heading date and SCA effects for grain yieldiplant in 4Lx6T of combining ability analysis in rice.

Salam et cii. (1996) reported that GCA and SCA variances Ibund for plant height, flag leaf sheath length, flag leaf blade length, number of

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spikeletlpanicle, sterility percentage and yield. indicated both additive and non-additive type of gene actions for these traits in rice. They also Ihund that good x poor, poor x poor combiners for grain yield/plant, spikelets/panicle.

panicle length, panicle/plant and 1000-grain weight indication overdominance and epistasis gene actions for these characters. A parent 'Kataribhogh' as a poor general combiner produced good specific combiner eI.osses.

Sham -ta ci cit (1996) also reported, from the study of 18 hybrids along with the parents, that the preponderance of non-additive gene action for plant height, grain weightlpanicle and grain yield/plant were observed in rice.

Additive gene action was found important for panicle bearing tillers/plant, panicle length and fertile spikelets/panicle.

Rao et at (1996) reported two good general combiner rice CMS lines 1R58025A and 1R62829A for grains/panicle, spikelet fertility, grain yield/plant. They also reported two crosses PushaA/1R2797-105 and MangalaA/1R2797-105 as best specific combiners for grain./panicle, spikelet fenility, and grain yield/plant on the basis of high magnitude of SCA performance. In analysis of 3 CMS lines ^x 13 restorer lines of combining ability of rice, Singh et at (1996) observed predominant additive genetic variance for plant height and days to 50% flowering and non-additive gcnetie variance for yield, number of panieles/plant, number of grains/panicle and 1000-grain weight. They also reported seven parents as good general combiners for yield and several yield components and one as a best parent for earliness and dwarfness. Crosses of CMS line, 1R58025A, with Jaya. T3, Manasarova, Sita, and UPR238 were suggested thr heterosis breeding due to its high and significant SCA effects.

Rajara and Maheshwary (1996) reported both additive and non-additive gene

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effects for grain yield/plant, days to heading, plant height, spikelets/spike, and harvest index, only non-additive gene effects for tiller/plant, spike length, grain/spike, and I 000-grain weight in wheat. From the ratio of GCA/SCA they found the preponderance of non-additive gene action for all the traits except plant height. They also suggested one cross as a most promising hybrid having both SCA and per se performance for grain yield, spike length and 1000-grain weight and live parents as good general combiners fbr its grain yield and other components.

Chen et cii. (1997) mentioned that yield/plant appeared to be mainly controlled by non-additive effects, while plant height and heading date were mainly conditioned by additive gene effects.

Padmavathi c/at (1997) also studied combining ability and heterosis for 10 characters in a 3L x 51 analysis and their 15 hybrids. GCA and SCA variances were significant for days to 50% flowering, number of tillers/plant, number of panicle/plant, I 000-grain weigh and thy matter production/plant.

Among the parents, two inbreds and two maintainers showed significant ("CA effects for more than one desirable trait indication their utility in heterosis breeding program. The crosses with high SCA effects were identified for each character.

Ganesan es at (1997) reported from a study conducted with 28 rice hybrids derived from four early (105-I 15 days) maturing varieties as lines and seven extra-early (70-90 days) varieties as testers. They observed the importance of both additive and non-additive gene action for yield and its component traits.

However, predominance of non-additive gene actions observed for yield and its component traits except plant height. ASDI6 among early parents and Heera and AS8901 I among extra-early parents were identified as the best combiners.

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Ramalingam ci aL (1997) reported from their study that the greater role of non-additive gene action was noticed for some yield contributing characters except plant height. Among the parents, 1R58025A and 1R54742 were found to have favorable genes lhr one or more characters along with grain yield.

The hybrid combination ZS97A!1R24 showed superior SCA effects for all the seven traits studied. It was followed by ZS97Af1R24, 1R58025A/lR29723 and 1R62829A/ 1R54742 with good SCA effects for six characters. Superior SCA effects were produced by involving all kinds of combinat ions viz., high x high, high x low, low x high and low x low general combiners.

Singh and Maurya (1997) also carried out the L x T analysis consisting of 60 hybrids involving 12 lines (8 cyto-sterilc lines and 4 maintainers) and five testers. The greater values of SCA than GCA variances, higher values of degree of dominance and lower predictability ratio were observed for all the eight characters including grain yield indicating the greater importance of non-additive gene actions for the traits studied. Cyto-sterile lines possessing tWA' type of cytoplasm were good general combiners for grain yield than CIVIA lines having 'MS577' type of cytoplasm. The general combining ability of testers showed that Narendra 118 was the best, followed by Saket 4 most of the characters. In general, the hybrids with high SCA effects involved either both or one parent as good general combiner and any cross which expressed high per se performance for a particular trait was derived from parents with good general combining ability for that trait.

Vivekanandan and Girldharan (1997) studied combining ability of SI. _x3L mating design on six yield-related traits of rice and reported additive gene action for 100-grain weight. Based on per se performance and GCA effects they suggested that ADT39 and White ponni were the best parents for the improvement of grain traits including grail) yield.

Roghell and Subbaraman (1997) observed significant variance due to Lx T 13

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for eight quantitative characters of rice and found preponderance of non- additive gene action for all the characters studied from the estimation of SCA and GCA variances and their ratio. They also reported five good general combiner parents for grain yield and six specific combiner crosses based on per se performance and SCA effects.

Ganesan and Rangaswamy (1998) studied with ÔL x 8T model and revealed higher GCA variance than SCA variance for all the characters studied except number of tillers/plant, productive tillers/plant, panicle length and yield/plant and thus predominance of additive gene action was found to be evident.

Considering GCA effects, the parents 1R62829A, White ponni and Ponni (tester) were identified as good general combiners for yield and its component characters. Considering SCA effects, 1R62829A/White ponni was found to he better than other crosses.

Rogbell ci at (1998) observed two best combinations of F1 s in 51- x 71 analysis of combining ability in rice due to predominance of non-additive gene action.

Selvarani and Rengasaniy (1999) found non-additive gene action was predominant for all the morpho-physiological traits except leaf area index in CA study in the 4L x 6T model for nine traits. Among the lines, JRSO and ADJ'37 and among the testers, 'I'NAU88022 and JR 192 were good general combiners for most of the traits. Three hybrids showed high specific combining ability effects for grain yield and other important traits.

Meenakshi and Amirthadevarathinam (1999) observed combining ability in semi-dry rice through line x tester analysis for major yield and physiological characters related with drought tolerance. A preponderance of additive gene action was observed for days to 50% flowering, harvest index single plant

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yield and praline content. Both additive and non-additive gene action was observed for productive tillers and chlorophyll stability index. Annada and Kallurunadajkar (tester) were the outstanding general combiners for all characters, excepting 100-grain weight. Two crosses were found to be best specific combiners for yield and yield contributing quantitative and physiological characters. The crosses with significant specific combining ability effects were due to the combinations of parents both of which were good or poor general combiners or any one was a good general combiner.

Kwak (1999) studied that the combining abilities of harvest index (HI) and productivity score (PS) from the partial six-parental diallel cross with _indica and i'ongil type rice varieties. The mean squares of GCA and SCA were highly significant for HI, PS, grain yield and straw yield. The variance of GCA effect was much larger than that of SCA effect in all the characters, showing preponderance of additive gene actions for these characters. Rice varieties Milyang 42, Suweon 307 and IR356 showed high GCA effects to the direction of selection for harvest index and productivity score, and the cross 1R747B,-6/Suweon3o7 did the highest SCA effects to the direction of selection of grain yield, harvest index and productivity score.

Yadav cc at (1999) studied combining ability for days to 50% flowering, days to maturity, plant height, flag leaf length, panicle length, number of ear bearing tillers/plant, percent pollen sterility, number of filled spikelets/panicle, grain yield/plant and harvest index from 31, x lOT analysis.

Among the male parental lines, the MDR358 appeared as the best general combiner for all the traits except days to 50% flowering and plant height. The .Jhona 349 was the best general combiner for earliness. The female line IR58025A was a good general combiner for grain combiner for grain yield/plant and its major components. The most promising specific

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combinations were 1R62829A/I liT 13610, 1R58025A/IETI 3303.

1R62829AJ1 E1 3386, and PMS3JVNDR358 for grain yield/plant.

Yilmaz and Konak (2000) reported non-additive gene action for spike length, number of grains/spike, spike weight, 1000-grain weight, while additive gene effects for plant height, spikeletlspike and total dry weight in handy in a L x 'F analysis.

l3ashar (2002) observed importance of both additive and non-additive gene action for plant height, days to 50% flowering, harvest index, and grain yield and additive gene action for 1000 grain weight. Generally, he found high x high general combiners produced best specific crosses and he also found a good specific cross evolving from parents having poor general combining ability.

Kumar et aL(2004) reported from the evaluation of a 3 lines x 9 testers mating design that combining ability analysis showed both additive and non- additive gene action. Among the three CMS lines 1R58025A and among 9 restorers PSRM-1-16-48-1, Pusa 1040 and RAU 141 1-4 were found to be good general combiners for yield other yield attributes. The hybrids 1R68$86AXPUSA 1040, IR58025AXGAUTAM, 1R68886A X PSRM-I-I6- 48-I were identified as good specific combinations for grain yield/plant and related characters.

Rashid et a/.(2007) studied 2Lx3T mating design with Bashmati rice genotypes and reported that highest significant heterosis was observed (61.9) in the cross Super Bashmati/DM-107-4 for yield/plant. The female Super Bashmati, male DM-25 and and DM-104-4 were to be good general general combiner. On the other hand the cross between Basmati-370/13M-25 and

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Super Bashniati/DM-107A were observed good specific combiner for yield/plant.

2.3 I-Jeterosis

The phenomenon of superiority ofF1 over its parents is heterosis (Syn. hybrid vigour). The term heterosis was coined by Shull (1908) for quantitative measure of superiority ofF1 over its parents and is usually referred to relative heterosis. The phenomenon of heterosis has been a powerful force in the evolution of plants and has been exploited extensively in crop production (Birchler ci at 2003).

Heterosis refers to the increase or decrease ofF1 value over the mean parental value (relative heterosis). From the view point of plant breeding, increase of F I over the better parent and/or the best commercial variety is more relevant.

The former is designated as heterobeltiosis (Fouseca and Patterson, 1968) and the latter as standard heterosis.

In rice, heterosis was first reported by Jones (1926) who observed marked increase in cuim number and grain yield in some F, hybrids in comparison to their parents. Since then, several rice researchers have reported the occurrence of this phenomenon for various agronomic traits e.g. yield, grain weight, grains/panicle, panicles/plaru, plant height, days to [lower etc.

(Vimani et at, 1981).

The literature reported on heterosis until 1987 is summarized by Virmani e- at (1981) and further updated by Virmani and Edwards (1983). These reports provided evidence for the occurrence of significant heterosis and lieteroheltiosis for various agronomic characters. 1-lowever, estimate of standard heterosis could not be made in most of the studies because the crosses were not made to develop F1 hybrid varieties. Majority of the reports

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were based on a few crosses which were perhaps made fbi conventional rice breeding program and did not necessarily involve the selection of parents to manifest strong heterosis, despite this limitation, the extent of heterosis was high in some cross combination. The most comprehensive work on the study and exploitation of intrusion has been reported from the Peoples Republic of China where F1 hybrids have been developed, released and are cultivated on commercial scale (Lin and Yuan, 1980). The success of hybrid rice in China encouraged the IRK! to revive research on hybrid breeding in 1979 (Anonymous, 1980) to exploit its potentials and problems outside China. The literatures available so far on heterosis in rice after 1980 have been reviewed here as follows:

Virniani ci at (1981) recorded significant positive heterosis, heterobeltiosjs and standard heterosis for dry matter production in the four crosses studied.

Bijral ci at (1989) observed standard heterosis ranging from-19.9 to 76.6%

over jay. Patnaik ci at (1990) also reported significant positive heterosis over mid parent (max 98.4%), better parent (max. 70.6%), and standard variety (max. 88.3%). Significant positive and negative heterosis for straw yield was reported by lshkumar and Saini (1983) and Jijaguna and Mahadevappa (1983). For harvest index also, both positive and negative heterosis was reported by several workers (Virmani ci al. 1981), Jijaguna and Mahadevappa (1983), Bijral et at (1989), and Patnaik ci at (1990).

Both positive and negative heterosis was reported for dry matter production by various workers. This may be due to the diFferences in the population, structure or environmental condition under which the experiments were carried out.

Murayama c/ at (1987) reported that in some rice F1 hybrids remarkable

heterosis was found in the photosynthetic rate of the single leaf i.e. most

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excellent F1 hybrids exceeded the mid-parent and higher parent by 57% and 5 1 % in its rate, respectively. The leaf nitrogen content was as high as that in photosynthetic rate. They also found positive and significant correlation between photosynthetic rate and nitrogen content.

Prakash and Mahadevappa (1987) evaluated 15 experimental rice hybrids over mate parents and check varieties. Relative and standard heterosis were calculated for 12 characters. Ftvbrids V202A11R134 19-I 13-1 and V20A/1R9761-19-1 showed significant positive heterosis over the male parent for grain yield. Many hybrids did not express significant positive standard heterosis in terms of yield and some of its components. This was due to high spikelets sterility ranging from 3.0 to 61.7%.

Sharma and Mani (1990) reported that four hybrids were produced by crossing 1R46830A with MahsuriR, Basmati370R, NarendraR. and Saket4R.

Magnitude of pollen parent heterosis and standard heterosis were worked out for yield and yield contributing characters viz days to 50% flowering, plant height, number of effective tillers/plant, panicle length, number of primary branches/panicle, number of spikelets/panicle, number of grains/panicle, I 000-grain weight and grain yield/plant. Heterosis for grain/plant was mainly due to high number of grains/panicle and 1000-grain weight. F1 hybrids I R46830A/Mahsuri R and I R46830A/Basmati37oR revealed significant pollen parent heterosis and sufficient standard heterosis for grain yield/plant.

Patnaik et aL (1990) found that 136 hybrids were developed utilizing four CMS lines (V20A, Zhen Shan 97A, 1R46829A and 1R46830A) and 34 elfective restorers. Heterosis, lieterobeltiosis and standard heterosis were found to be significant for grain yield and other yield attributing characters in most of the hybrids. The heterosis for grain yield was mainly due to the significant heterosis for the number of spikelets/panicle, test weight and total dry matter accumulation. Interestingly, it was found that most of the higher

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yielding hybrids were accompanied by significant negative heterosis for harvest index. Hybrids shorter than the shortest parent and earlier than the earliest parent were not observed; hybrids with intermediate to tall plant height having nun-lodging habit could be developed. Eighteen hybrids gave more than 20% grain yield than the standard checks.

Young and Virmani (1990) evaluated the 140 crosses and 17 parents Ibllowing line x tester design in six environments and two seasons and reported that the hybrid were superior to their parents in yield. Hybrids flowered earlier and were taller than the parents. Substantial heterosis, heterobeltiosis and standard heterosis were observed in different environments. Heterosis was higher in \VS (stress environment) than in 1)S (favorable environment). Twenty four hybrids out yielded the standard check significantly. For days to flowering, the overall mean heterosis, heterobeltiosis and standard heterosis were and negative values. Hcterosis for plant height did not change the plant type of hybrid from semi-dwarf to tall because the parents possessed same dwarfing gene.

A study was made to assess the nature and extent of heterosis and heterobeltiosis for yield and its components in a 7 x 7 diallel excluding reciprocals (Lokaprakash er at, 1992). Heterosis for all the characters was evident in most of the hybrids studied. Heterosis for yield was mostly due to simultaneous heterosis for number of productive tillers, panicle weight, panicle length, fertile spikelets/paniele, 1000-grain weight and harvest index.

Bobby amd Nadarajan (1994) also evaluated the performance of 50 rice hybrids by combining ability and heterosis. The line x tester method of analysis was followed involving 10 male sterile lines and five restorer lines tbr the study. The per se perIbrmance of the hybrids appeared to be not dependent on the SCA effects or heterosis percent. Therefore, for commercial

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exploitation, the selection of hybrids should be based on per se perlormance and standard heterosis. The hybrid TNMS37A/ARCI 1353R could be judged as the best hybrid followed by improved SonaA/ER46R based on their per se performance, standard heterosis and hybrid seed production capacity.

Julfiquar et at (1994) reported that four inc/ica/japonica and four japonica//aponica hybrids involving eight wide compatibte varieties and having one parent common were produced. The parental lines and the F1 hybrids were evaluated under similar environment and six physiological characters were monitored. The mean F1 value of indica//aponica hybrids with respect to all the traits in either four week after transplanting (4 WAT) or six week after transplanting (6 WAT) or both. Much difference in mean heterosis was observed between indica//aponica and japonicaijaponica crosses in respect to leaf area at 4 WAT, plant dry weight. leaf area index at 6 WAT, leaf area ratio of 6 WAT, CGR and net assimilation rate (NAR) at 4 WAT. In general, the degree of heterosis in two kinds of F1 hybrids in this study followed the general trend: indica/japonica>/aponica/japonjca. Higher heterosis of inclical/aponica hybrids at early vegetative stage was due to more dry matter production and increased CUR than japonica/japonica crosses.

Lee ci al. (1995) observede heterohettiosis for dry weight and leaf area at heading and for panicles/plant. At least in one hybrid they observed heterobeltiosis for chlorophyll content in the flag leaf. l-leterobeltiosis for yield was II % and 4% for the two hybrids, respectively.

Pandey et at (1995) studied 30 hybrids and reported that most of the crosses manifested significant heterosis for grain yield and panicle number/plant, panicle length, 1000-grain weight, grains/panicle and days to maturity. The range of heterosis for seed yield/plant was-96-7 to 258.2%over the better

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parent, -96.1 to 268.2% over mid-parent and 96.3 to 301.6% over the standard variety.

Yolanda and Das (1996) also reported the heterosis from the 36 hybrids which were developed utilizing three CMS lines (V20A, lR58025A and I R62829A) and 12 testers. They reported on the extent of heterosis of days to Ilowcring. panicles/plant, grains/panicle. spikelet fertility. 100-grain weight and grain yield/plant. The hybrid 1R62829A1C037 revealed heterotic vigour for number panicles/plant and grain yield/pant (19.83%). The standard heterosis was negative in as many as 34 hybrids.

The study on the selected seven crosses revealed that heterosis over the mid and better parent were negative for days to panicle emergence and positive for panicles/plant, grain yield/pant, dry matter production and harvest index.

The superiority of ASDI6 and Ileera among parents and AD136/Kalyani II, ADT36/AS890I 1 and 1R50/lleera among hybrids was confirmed based on the per se performance and heterosis over better parent in the subsequent season (Ganeasan etal., 1997).

Chen ci at (1997) reported heterosis for the hybrids from reciprocal crosses of FGMS and wide compatibility varieties (WCVs). They mentioned that TOMS xTGMS hybrids showed 13.9% heterosis for spikelets/panicle.

respectively, But negative heterosis for plant height and days to heading were observed.

Lin and Liang (1997) reported that the indica hybrids Shanyon 63 and Teyon 63 showed considerable heterobeltiosis for grain yield due to the higher number of productive tillers/plant. Tillers/plant and grains/plant were responsible for heterosis for dry matter production. Slight heterosis was found for croi growth rate.

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Panwar er al. (1998) reported that the standard heterosis was found to he significant for all the traits studied. It was both negative and positive for grain yield/plant (-0.57 to 54.75%), panicles/plant (-14.84 to 89.14%) and grains/panicle (-16.04 to 43.28%), and negative for 1000-grain weight (- 34.55 to -5.82%). Positive and significant standard heterosis was observed in six hybrids for grain yield/plant, in 12 hybrids for panicles/plant and in seven hybrids for grains/plant. 1R58025A/1R0N89-54 showed positive and significant standard heterosis [hr grain yield/plant, panicles/plant and grains/panicle.

Sitaramaiah c/. at. (1998) reported that al least two out of 10 promising rice hybrids exhibited significant and positive heterosis for panicle length. Nine hybrids exhibited a very high positive standard heterosis for number for 1000-grain weight because the check had bold grains.

Singh and Zaman (1998) studied IS F1 s along with six parents from a 6x6 half diallel involving diverse parents for physiological efficiency and reported that the cross, iayalSwarnaprabha, which exhibiled a high heterobeltiosis for biological yield (54.9%), also showed a significant positive heterosis for grain yield, HI, CGR, LA! and leaf area/plant.

Mishra and Pandey (1998) evaluated heterosis of the hybrids, utilizing two CMS lines (V20A and 1R62829A) and 19 elite genotypes suited to irrigated situations. They reported that about 17-20% of all the hybrids manifested significant and positive heterobeltiosis and standard heterosis for seed yield in the range of 44.7 to 230.9% and 42.4 to 8 1.4%, respectively. Heterosis for seed yield was due to the positive and significant heterosis Ibr components like panicle length and 1000-grain weight. Most of the higher yielding hybrids manifested positive heterosis for harvest index and number of spikelets/panicle.

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Sathya et at (1999) assessed the nature and extent of heterosis in a line x tester design with the lines of 1R58025A and 1R62829A. They reported significant standard heterosis for productive tillers/plant and grain yield/plant.

Seetharamaiah ci at (1999) evaluated the 10 rice hybrids and standard heterosis was estimated for yield and yield components. Plant height.

followed by panicle length did not play significant role in the expression of heterosis. Standard heterosis for grain yield was manifested through more number of spikelets/panicle and number of ear bearing tillers/meter2.

\'ishwakarma ci at (1999) reported from the evaluation of 65 rice hybrids developed by crossing 1R58025A and PMSIOA with 45 diverse male parent.

The highest range of heterosis was noted for yield characters. A perusal of the top heterotic crosses revealed that none of the crosses were top heterotic for all the traits simultaneously. The cross IR58025AxNDRK5042 showed higher potential for effective tillers, grain yield/plant and harvest index. The hybrids 1R58025xNI)RK5042 showed the highest heterosis for yield/plant (108.8% better parent and 73.33% standard heterosis) followed by 1108025A/NDR07 (100% better parent and 60.50% standard heterosis) and I R58025A/NDRK5O2o (89.76% better parent and 65.701/0 standard heterosis). The high heterosis for grain yield was accomplished by heterosis for the effective tillers/plant.

Rashid et at (2007) studied 2Lx3T mating design with Bashmati rice genotypes and reported that highest significant heterosis was observed (61.9) in the cross Super Bashmati/DM-107-4 for yield/plant. The female Super Bashmati, male DM-25 and and DM-104-4 were to he good general general combiner. On the other hand the cross between Basmati-3701DM-25 and Super Bashmati/DM-107-4 were observed good specific combiner for yield/plant.

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Saleem ci at (2008) reported that heterosis and heteroheltosis ranged -2 1.06 to 60.13 percent and -33.34 to 42.99 percent respectively for leaf area, -3.941 12.98 percent and 3.25 to 32.21 percent for plant height, 17.88 ₁₀ 53.10 percent and -25.90 to 23.97 percent for panicle density, -8.80 to 32.43 percent and -24.32 to 19.29 percent for harvest index, 7.54 to 58.77 percent and 12.88 to 104.37 percent for biological yield per plant. The results indicate that improvement of' grain yield can be efficient through making some compromises within limits among morpho-physiolocal yield traits.

2.4 Character associations

Yield being a complex character is dependent on a number of components.

.2

Knowledge on the magnitude and direction of association between yield and 3 its component morphological characters and among them will serve to make

A

simultaneous selection for more than one character. Many workers attempted to estimate the interrelationships between different traits so as to fix selection . parameters.

Co

co 2.4.1 Relationship between Combining ability and Heterosis

00 Relationship between the general combining ability effects of parents and heterotic performance in their F1 s of chick pea revealed that in majority cases the cross combinations involving parents with high and low GCA effects manifested maximum heterosis, Mian and Bahl (1989).

A feasible genetic basis provided by Langham (1961) for the of high x low (H x 1) combination was supported by this experiment.

Salam c/ at (1996) reported that good x poor, poor x poor combiners for grain yield/plant, spikelets/panicle, panicle length, panicle/plant and 1000-

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grain weight indication overdominance and epistasis gene actions for these characters.

Combining ability for eight characters studied by Wang and Tang (1988) indicated that panicle number/plant was mainly affected by GCA effect of A lines and grain yield/plant was unaffected by GCA of P. lines. GCA effects of A and It lines played an important role than SCA effect. The results indicated veiy close and consistent positive relationship between heterosis and combining ability implying that the heterosis of a hybrid combination could be predicted reliably by combining ability.

Considering the over all heterotic combinations over mid-parent, out of 133 heterotic crosses

45

significant GCA effect for both the parents, 61 were significant for either of the parents 27 were of non-significant GCA effects.

In case of pollen parent heterosis majority heterotic crosses were manifested

when both the parents were possessed significant GCA effects (Basher,

2002).

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CHAPTER III

MATERIALS AND METHODS

t t gvCiC ^-

I-

J

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CHAPTER 111

MATERIALS AND METHOI)S

The experiments were conducted during November, 2007 to November, 2008 at Bangladesh Rice research institute (I3RRI), Gazipur. Bangladesh. Two separate expenments were conducted, one for crossing programme and other for evaluation olparents and hybrids.

3.1 Climate and soil

The experimental site was at 24.000 N latitude and 90.251 E longitude with an elevation of 8.4 meter from the sea level. The experimental site is undcr the sub-tropical climatic zone. During the experimentation the rainthll occurred at least 200 mm/month from the month of June to September. It is characterized by hi&h rainfall, cloudy sky to clear sunshine day, low temperature at the later part and moderate to high temperature in the earlier part. The maximum and minimum mean monthly temperature and relative humidity for the growing season are presented in Appendix 8. The soil of the experimental field was clay loam in texture having p11 of 6.2. It belongs to the Chitra soil series of red brown terrace.

3.2 hybridization programme

The crossing programme was established during Boro-2007 seasons. The materials and methods are mentioned in the following sections.

3.2.1 Materials

The experimental materials chosen for this investigation consisted of five female viz BRRI3A, }3RRI9A, 1132A, 1R73328A and BRRIIOA and eight male parents viz. BR827R, BRIGSR, BR736R, 1310723-1-1-21Z, 1310839-41-

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5-I It. BRRI I OR, BRRI 1 2R and BRRI I 7R were selected based on their perlhrmance and geographic origin (Table 1).

3.2.2 Methods

The seeds of selected 5 female and 8 male parents were sown separately durin g Boro 2007 in a staggered way so as to get synchronization of the flowering with diverse durations and to facilitate easy hybridization in a Line (CMS line) xTester (Restorer) fashion to get 40 1:1 hybrids. The seeds of male parents and CMS lines were raised in well-prepared wet seed beds. Thirty- days-old seedlings were transplanted with a spacing of 20 x 15 cm. The crosses were done by hand pollination according to the combinations required using CMS lines as female parents. Recommended agronomic practices and intercultural operation were taken when necessary. Before anthesis (between 8.00 am to 9.00 am) the panicles which were to be open on the day were bagged in both CMS lines and male parents. At the time of anthesis, pollen from the niale parents were collected by gentle tapping and dusted on the panicles of the CMS lines and covered with glycine bags and after pollination these were again covered and tagged. Mature seeds were collected from each cross from the tagged panicles. Sun dried and stored separately in paper bags with proper labeling.

3.3 Evaluation of parents and hybrids

Forty hybrids along with their parents were sown separately during T. Anian, 2008. Twenty-five-day-old seedlings were transplanted on August. 2008 with a spacing of 15 x 20 cni with single seedling per hill in the main field in a RCB design with three replications. The unit plot size was 1.5 sq. meter.

Sampling area was one meter square. The recommended agronomic practices and plant protection measures were followed as and when needed.

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3.3.1 Experimental site and duration

The experiments were carried out at the hybrid rice experimental plots of I31MI lhrm during July to November 2008 J. Aman season).

Table 1. Brief introduction of the parental materials used in this study SI.. Parent identity Origin Characteristics

I BRRI3A CMS BRRI

--

I..ower grain weight

2 I3RRI9A CMS BRRI Short plant height and duration 3 1131\ CMS Indonesia Low yield

4 IR7332$.'\ CMS IRRI Higher grain / panicle 5 BRRI I OA CMS I3RRI Short duration

6 BR827R Restorer BRRI Higher plant height and low spikelet Ièrtihty (%) 7 IJRIbRR Restorer BRRI I.ong panicle and more panicle / meter square S 13R736R Restorer BRRI Low tilkring ability

9 13R6723-1-1-2R Restorer 31(1(1 High spkelet fertility (%) 10 1310839-4 1-5-i R Restorer BRRI Higher yield

11 BRRI I OR Restorer BRRI Higher tillering ability 12 BRRI 1 2R Restorer BRRI Medium growth duration 13 131ZR1 1 7R Restorer BRRI Bold grain

14 BRRI dhan33 Inbred 31<1(1 Short duration

15 I3RRI dhan39 inbred BRRI Short duration and long slender grain

3.3.2 Seed germination

1:1 seeds of 40 hybrids along with their parenis and two checks were sprouted separately. Hybrids seeds were soaked in sterilized Petri dish with sufficient amount of vitavax to avoid tbngal infection. After 24 hours of soaking the Petri plates were incubated in germinator at 30-32 °C temperature for uniform germination. The seeds of parents and check varieties were soaked and provided same facilities for proper germination.

3.3.3 Field plot technique 3.3.3.1 Land preparation

The experimental _plotwas at a lower elevation with high water holding capacity, shade free, irrigated and well drained. The land was prepared thoroughly by 3-4 times ploughing and eross-ploughing followed by I acidering.

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m

C

r

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LEGEND: 11 13 1111RII7R, CIBRRI dhan33, C213RR1 dhan39

FIGURE 3: I'IIENOTYPIC DIVERSiTY OF PARENTAL LINES AND CHECKS (P13, Cl, C2)

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-i'r

5::nI4ar Irvt

-

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::

PLATE 1: CROSSING BLOCK OF PARENTAL LINES

Mom

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IV

PL..vrF: 2: S1'!KELET CLIPPING FOR VA( IlAlAl ION OF P011 IN \IION

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rLAIL: 3: (OLLECIION OF MALE FlOWER

PLAtE 4: ARTIFICIAL POlLINATION FOR FIYBRIDIZALION

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. wi-s.

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:

• :*Jj

)i •4ite!tt,*e,(j•

ftp#z,i jtl*1

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!'IAll 4: I1\BJtIi)I7.Fl) \NI) Ll.\(;(;Eu lLs1LF: I'I.A\ 1

PlATE 4: ll\lWiI)I/.[I) Ffll\iI PLA.\i' BEARING F1 SEEDS

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3.3.3.2 Plot layout and 'transplanting

The experiment was layed-out in a RCB design with three replications.

Twenty-five-days old seedling was transplanted at a spacing of 20cm between rows and 15cm between plants with single seedling per hill. Each entry was