Hybridization and Pedigree Nursery for Transplanted and Direct-seeded Irrigated lowland rice varieties
B. Rice Varietal Improvement Group
VI. Development Of Thermo-Sensitive Genetic Male Sterile (TGMS) Lines and TGMS-Based Two-Line Hybrid Rice
Project Leader: SH Escamos
The discovery of thermo-sensitive genetic male sterility in rice provided new avenues to further exploit heterosis using the two-line system.
TGMS are genic male sterile genotypes whose fertility/sterility behavior is conditioned by temperature regimes (Virmani,1996). This system is useful in the Philippines where temperature differences exist due to elevation, latitude and time of year. The increased chances of finding high yielding hybrids and the more straightforward seed production of TGMS lines makes this system more economically viable.
With the release by the National Seed Industry Council (NSIC) of 2 TGMS-based hybrid rice varieties, the collaborative project between UPLB and PhilRice has demonstrated that breeding and use of TGMS lines to develop two-line hybrids can be successfully done in the Philippines. The project is aimed at developing stable and improved TGMS lines with added focus on earliness and shorter stature. Likewise, it aims to develop high yielding two-line hybrids that are pest resistant and with acceptable grain and eating qualities.
Development of New and Diverse TGMS Lines through Hybridization and Selection
SH Escamos, MAT Talavera, TMMasajo
To keep up with the challenge of developing better two-line hybrids, continuous development of new and more improved TGMS lines is an essential component that needs to be pursued. The objective of the study is to develop new and diverse TGMS lines through hybridization and selection.
Earliness and shorter stature, resistance to pests and diseases and good grain quality are some criteria considered in selection. Development of TGMS lines with low critical fertility point will help ensure safe and successful production of F1 seeds at male sterile environment (MSE).
Highlights:
• Research activities on the development of new improved and stable TGMS lines through hybridization and selection at both male sterile environment (MSE) and male fertile environment (MFE) were continued during the year.
• At MSE (Los Banos), TGMS lines and selected male parents were assembled and planted for making crosses. Planted during the year were 87 F1s, 62 F2 populations (30 during the dry and 32 during the wet season), and 2007 lines in the F3-F7 generation. From the 62 F2 populations and pedigree nurseries grown during the year, 1745 plants were selected.
• At MFE, 631male sterile selections from the 2014 dry season pedigree nursery at MSE were brought to Tublay, Benguet for evaluation and seed increase. Planted in Majayjay, Laguna were 853 male sterile selections from the 2014 wet season pedigree nursery at MSE.
• During the year, thirty-one (31) selected male sterile lines from F5-F7 were included in the TGMS observation nursery at MSE for evaluation of stability of sterility. Eleven uniform TGMS lines were identified promising based on phenotypic acceptability and complete male sterility. Seven of these lines were used in generating new experimental hybrids during the 2014 wet season to evaluate their performance as female parent. These lines will be planted in Tublay, Benguet for further evaluation and seed increase.
Development of New and Diverse TGMS Lines through Recurrent Selection
MG Ortiguero, TM Masajo
To reinforce TGMS breeding work at PhilRice Los Banos, an initiative to develop TGMS lines through recurrent selection was added. Recurrent selection as a breeding method is generally used in cross-pollinated crops but could also be employed in self-pollinated crops like rice using genetic male sterility system to facilitate natural cross pollination. The main purpose of the method is to concentrate on fewer individuals in the population desirable traits through recurrent cycles of intercrossing and selection. Compared to the generally used hybridization and pedigree selection, intercrossing among individuals in recurrent selection keeps plants in heterozygous conditions allowing for more chances of genetic recombination.
Highlights:
• The study has accumulated breeding materials from recurrent selection where potential TGMS parents can be derived and identified.
• Twenty-nine (29) crosses were generated in 2014 dry season for reinforcement of composite population. These crosses were planted and evaluated in 2014 wet season to produce F2 seeds needed in the composite population.
• In 2014 dry season, 452 F2 populations and 80 F4 lines were grown and evaluated in pedigree nurseries at MSE site (Los Baños). Selected were 744 F2 plants (637 sterile and 107 fertile) and 72 F4 male sterile plants. Selections were ratooned and brought to MFE site (Tublay, Benguet) for evaluation and multiplication of seeds in 2014 wet season. Selected and harvested were 437 F2 plants and 57 F4 plants which will be planted this 2015 dry season. Fertile selections were advanced to F3 at MSE site (Los Baños) in 2014 wet season.
• At MFE site, 1018 F2 and 240 F3 plant selections were grown for evaluation and seed multiplication in Majayjay, Laguna while 243 F3 plant selections were grown in Tublay, Benguet in 2014 dry season. Selected and harvested were 764 F2 plants and 206 F3 plants from Majayjay, Laguna and 526 F3 plants from Tublay, Benguet. These selections composed the F3 and F4 pedigree nurseries at MSE site (Los Baños) in 2014 wet season.
• In 2014 wet season, 871 F3 lines and 732 F4 lines were planted at MSE site (Los Baños) in 2014 wet season. Selected
from these lines were 733 F3 plants (634 sterile and 99 fertile) and 549 F4 plants (465 sterile and 84 fertile). Selections were ratooned and brought to MFE site (Majayjay, Laguna) for evaluation and multiplication of seeds in 2015 dry season.
Fertile selections will be advanced to F4 and F5 at MSE site (Los Baños) in 2015 dry season.
• In 2014 wet season, promising F4 lines were used in test crosses to generate experimental hybrids for early generation testing of combining ability and yielding ability of F1 using these F4 lines. Generated were 21 F1s which will be grown and evaluated in the Hybrid Observation Nursery this 2015 dry season.
Identification and Development of Pollen Parents for Two-Line Hybrids MAT Talavera and TMMasajo
Essential to hybrid development programs for both two-line and three-line system is the availability and identification of potentially good- performing pollen parents. Characters such as yield, plant height, lodging resistance, maturity, resistance to pest and diseases, grain acceptability, tolerance to abiotic stresses, and pollen–shedding ability are traits considered in the selection of pollen parents. Drawing pollen parents from existing inbred variety development programs has been the common practice in hybrid breeding. But lately, with growing interest on hybrids and increased demand for pollen parents, finding suitable and diverse inbreds as male parents of hybrids has become increasingly difficult. Furthermore, access and use of improved germplasm developed and introduced from elsewhere are covered by PVP and MTA and provisions therein could be rather restrictive.
While the TGMS project at Los Banos will continue to identify and source pollen parents from available materials, it is doing breeding work purposely to develop better pollen parents for TGMS hybrids.
Highlights:
• The study is producing breeding materials from composite populations by recurrent selection where potential pollen parents can be identified and extracted.
• A total of 673 (dry season) and 472 plant selections (wet season) from composite populations were established in pedigree nurseries (F3 to F7) during the year. Some promising uniform lines in the advanced generation were used as parents in making experimental hybrid during the wet season and will be evaluated in 2015 HON. Five (5) uniform lines selected as potential pollen parents during the wet season will be used in
making experimental hybrids in the 2015 dry season.
• Converting (morphological tagging) green-base pollen parents into purple-base genotypes will facilitate identification of true F1 hybrids from selfed individuals, if any, as early as the seedling stage. This will eliminate the need for the costly and lengthy “grow-out tests”. Two highly selected TGMS hybrid pollen parents are being morphologically tagged with purple coloration at the leaf sheath through backcrossing. Seven (7) uniform lines extracted from BC3 and BC4 and evaluated in the pedigree nursery were selected and utilized as pollen parents in making new experimental hybrids during the wet season. Likewise, 18 and 16 purple-based lines derived from the BC5 and BC6, respectively, were planted for purification and further evaluation. Fifteen (15) test crosses with different TGMS lines were made during the dry season using the selected uniform purple-based lines. These hybrids were evaluated in the 2014 wet season hybrid observation nursery and one of these hybrids is the highest yielder in the nursery (10,636kg/ha).
• Selected pure lines of purple-based version of TG101M and TG102M from BC5 were used as pollen parents to generate purple version of Mestiso19 and Mestiso 20. Two purple-based version of Mestiso 20 were made and tested in the preliminary yield trial during the wet season. Results indicate that the hybrids are comparable with Mestiso 20 in characters such as plant height, tiller number and maturity. Data on yielding ability has yet to be verified. Meanwhile, 8 purple based experimental hybrids were produced during the wet season (3 were M19 while 5 were M20 version). These hybrids will be entered in the 2015 dry season Advance Yield Trial (AYT) for agromorphic and yield comparison with M19 and M20.
Development of Two-Line Experimental Hybrids SH Escamos, MAT Talavera,TM Masajo
In order to find good performing hybrids, test cross of the TGMS lines with as many and as diverse pollen parents available is necessary..
Not all hybrids exhibit positive heterosis for economic traits, hence there is a need to produce a large number of experimental hybrids for testing and evaluation. The objective of the study is to generate as many experimental hybrids as possible to increase the chances of finding heterotic hybrids.
Highlights:
• Two-line experimental hybrids were generated through handcrossing using 15 promising TGMS lines and 100 pollen parents. Promising lines from the NCT, the UPLB breeding nurseries, NSIC released varieties, wide hybridization-derived lines and advance lines derived from recurrent selection were used as male parents.
• Two hundred fifty-two (252) new experimental hybrids during the dry and 360 during the wet season were produced.
Performance of the new hybrids produced during the dry season were evaluated in the hybrid observation nursery during wet season while those generated during the wet season will undergo evaluation in the coming 2015 dry season.
Evaluation and Field Performance Testing of Promising Hybrids DJ Lalican, MAT Talavera. SH Escamos, TM Masajo
Before a hybrid can be nominated to the NCT, it has to pass a series of evaluation and testing to determine its overall performance. The experimental hybrids have to undergo testing in the Hybrid Observational Nursery (HON) to initially eliminate inferior performing hybrids. Selected hybrids are elevated to the preliminary yield trial and advance yield trial for a more thorough evaluation for yield, insect and disease reaction and grain and milling qualities. Promising hybrids are channeled to multi-location and yield potential trials.
The objective is to evaluate the performance of experimental hybrids and identify and select the best performing hybrids that can be channeled to the National Cooperative Tests.
Highlights:
• One hundred sixty (160) experimental hybrids were evaluated in the Hybrid Observational Nursery (HON) during the dry season using Mestiso 19 and Mestiso 20 as hybrid checks, and
PSB Rc82 and NSIC Rc222 as inbred check varieties (Table 55a). Thirty-one (31) hybrids were identified better than the higher yielding inbred check NSIC Rc222, however, only 5 hybrids gave more than 15% yield advantage (YA ranged from 16.9-35.4%). HON 109 gave the highest yield (10,636ha) followed by HON 74 (9400kg/ha). F1 seeds of the promising hybrids were produced during the wet season for further testing in the hybrid preliminary yield trial (HPYT) in the 2015 dry season.
• Meanwhile, 252 new experimental hybrids were evaluated in the Hybrid Observational Nursery (HON) during the wet season using the same checks (Tables 1a-1c). Thirteen (13) were identified better than the higher yielding inbred check NSIC Rc 222. Yield advantage ranged from 15 to 45%. F1 seeds of these hybrids will be produced this 2015 dry season for further testing in the hybrid preliminary yield trial (HPYT).
Table 55a. Grain yield (kg/ha) of good performing hybrids in the HON, 2014 dry season.
Index No. 2014 WS PLOT NO. 2014 WS
Yield Yield Advantage
M1
9 M2
0 NSIC Rc
222 PSB
Rc82
1996 HON 109 10636 40.
0 - 35.4 48.6
1963 HON 74 9400 23.
7 - 19.6 31.3
2028 HON 131 9300 22.
4 - 18.3 29.9
1965 HON 78 9238 21.
6 - 17.6 29.0
1936 HON 60 9189 20.
9 - 16.9 28.4
1890 HON 8 8925 17.
5 - 13.6 24.7
*No data on yield advantage over M20 due to missing sample.
Table 55b. Grain yield (kg/ha) of good performing hybrids in the hybrid observation nursery, 2014 wet season (Set 1).
Index No.
2013 WS PLOT NO.
2013 WS Yield Yield Advantage
NSIC Rc 222 PSB Rc82 M19 M20
2073 HON 16 7049.6 45.0 85.0 39.9 68.2
2187 HON 5 6567.5 35.1 72.3 30.3 56.7
2114 HON 10 6547.4 34.7 71.8 29.9 56.2
2060 HON 8 6434.7 32.4 68.8 27.7 53.5
2225 HON 145 6035.2 24.2 58.4 19.8 44.0
Table 55c. Grain yield (kg/ha) of good performing hybrids in the hybrid observation nursery 2014 wet season (Set 2).
Index No.
2013 WS PLOT NO.
2013 WS Yield Yield Advantage
NSIC Rc 222 PSB Rc82 M19 M20
2304 HON 237 6694 182.8 96.2 69.9 82.3
2337 HON 242 6347 168.2 86.0 61.1 72.9
2322 HON 217 5993 153.2 75.6 52.1 63.2
2246 HON 214 5829 146.3 70.9 47.9 58.8
2302 HON 212 5767 143.7 69.0 46.4 57.1
• In the hybrid preliminary yield trial (HPYT), 40 experimental hybrids were evaluated during the dry season (Table 56a and Table 56b). Three (3) hybrids were identified more superior than the higher yielding inbred check (NSIC Rc222), however, only 1 hybrid yielded more than one ton higher. HPYT 400 gave the highest yield (10,179kg/ha) with a yield advantage of 23.5% over NSIC Rc 222 and 23.3% over Mestiso 19.
Likewise, 48 two-line hybrids were evaluated during the wet season (Table 57a and Table 57b). Seven (7) hybrids outyielded the inbred check (NSIC Rc 222) where 4 hybrids yielded one ton higher. Highest yield obtained was 7268 kg/ha with a yield advantage of 33.1% over NSIC Rc222 and 70.1%
over Mestiso 19.
Table 56a. Yield of good performing hybrids in the preliminary yield trial, 2014 dry season (Set 1).
Index No.
GRWT Yield Advantage
Index No M19 M20 Rc222 Rc82 HPYT 127 400 10179 23.3 22.4 23.5 22.8 HPYT 425 425 8426 2.0 1.3 2.2 1.6 HPYT 386 386 8410 1.8 1.1 2.0 1.4 HPYT 421 421 8381 1.5 0.8 1.6 1.1 HPYT 427 427 8340 1.0 0.3 1.1 0.6
Table 56b. Yield of good performing hybrids in the preliminary yield trial, 2014 dry season (Set 2).
Index No.
GRWT Yield Advantage
Index No M19 M20 Rc222 Rc82
HPYT 426 436 8473 2.6 1.9 2.8 2.2
HPYT 349 349 8014 -2.9 -3.7 -2.8 -3.3
HPYT 356 356 7966 -3.5 -4.2 -3.4 -3.9
HPYT 443 443 7819 -5.3 -6.0 -5.2 -5.7
HPYT 448 448 7516 -9.0 -9.6 -8.8 -9.3
Table 57a. Grain yield (kg/ha) of good performing hybrids in the preliminary yield trial, 2014 wet season (set1).
Index No.
GRWT Yield Advantage
Index No M19 M20 Rc222 Rc82 HPYT 456 456 5939 14.1 - 8.7 25.7 HPYT 459 459 5936 14.0 - 8.6 25.7 HPYT 356 356 5393 3.6 - -1.3 14.2 HPYT 460 460 5357 2.9 - -2.0 13.4 HPYT 458 458 5352 2.8 - -2.1 13.3
Table 57b. Grain yield (kg/ha) of good performing hybrids in the preliminary yield trial, 2014 wet season (set 2).
Index No
GRWT Yield Advantage
Index No M19 M20 Rc222 Rc82
HPYT 473 473 7268 39.4 - 33.1 28.9
HPYT 476 476 6843 31.2 - 25.3 21.3
HPYT 477 477 6738 29.2 - 23.4 19.5
HPYT 478 478 6684 28.2 - 22.4 18.5
HPYT 471 471 5955 14.2 - 9.0 5.6
• Eight (8) promising hybrids during the dry and 14 during the wet season comprised the advance yield trial (AYT) conducted during the year. During the dry season, one hybrid yielded a much as NSIC Rc222, however, during the wet season 4 hybrids yielded one ton higher than the said check with a yield advantage ranging from 29.5 to 35.2%. These hybrids will be undergo another season of testing. F1 seeds will be produced in preparation for entry to multi-location trials and eventually to the National Cooperative Test (NCT).
Table 58a. Grain yield (kg/ha) of good performing hybrids in the advance yield trial, 2014 dry season.
Index No.
2014 WS PLOT NO.
2014WS Yield Yield Advantage
M19 M20 NSIC Rc 222 PSB Rc82
AYT 101 - 7973 11.2 10.7 -0.2 15.4
AYT 72 - 7678 7.1 6.6 -3.8 11.2
AYT 90 - 7618 6.3 5.8 -4.6 10.3
AYT 105 - 7535 5.1 4.6 -5.6 9.1
AYT 118 - 7355 2.6 2.1 -7.9 6.5
Table 58b. Grain yield (kg/ha) of good performing hybrids in the advance yield trial, 2014 wet season.
Index No.
2014 WS
PLOT NO.
2014 WS Yield Yield Advantage
M19 M20 NSIC Rc 222 PSB Rc82
126 - 6000 23.4 - 35.2 50.1
125 - 5910 21.6 - 33.1 47.9
128 - 5749 18.3 - 29.5 43.8
127 - 5748 18.2 - 29.5 43.8
123 - 5349 10.0 - 20.5 33.8
F1 Seed Production of Two-Line Hybrids for Testing and Evaluation SH Escamos, MATalavera and TMMasajo
Producing sufficient amounts of F1 seeds for testing is essential in the development of hybrids. This activity will see to it that breeding advances will not be constrained by limitations in the ability to produce/reconstruct adequate amount of seeds of experimental hybrids particularly those destined for preliminary yield trial and the NCT.
• F1 seeds of 108 promising experimental hybrids for PYT and AYT were successfully produced (75-280 grams/hybrid) during the year.
• 8kg of PRUP 10 were produced during the dry season. S X P plots during the wet season was affected by typhoon Glenda.
Highlights:
• One hybrid entry in the NCT performed very well during the 2013 wet and 2014 dry season trial, ranked No 2 and No 5 among the medium maturing hybrid entries with 4.8% yield advantage over the check Mestiso 19.
• Eleven new TGMS lines were identified.
• Three (3) promising hybrids for multi-location
trial and eventually for NCT were identified.
The project has accumulated breeding materials from
recurrent selection where potential TGMS and pollen parents can be used in the near future. Purification of identified promising TGMS and pollen parents and utilizing them in testcrosses is on-going.
• Incorporating purple leaf sheath base coloration into male parents of two hybrids through backcrossing has been done.
Testing of identified purple based pure lines as pollen parents of PRUP TG101 and PRUP TG102 to generate purple-based M19 and M20 is in progress. Likewise, these lines are being testcrossed with other TGMS lines to determine their potential as pollen parents
• Incorporation of wide cytoplasm from different sources such as O. glaberrima, O. rufipogon and O. barthii i is being done in TGMS lines development