Hybridization and Pedigree Nursery for Transplanted and Direct-seeded Irrigated lowland rice varieties
B. Rice Varietal Improvement Group
VIII. Development of Rice Varieties Adapted to Rainfed and Stress Environments
VIII. Development of Rice Varieties Adapted to Rainfed and
traits, viz., size, shape, color, awning (Figure 58), had Shanon Weaver Diversity Index of 1.7 to 1.8.
• The seed culture of 16 TRVs identified 14 (87.6%) genotypes responsive in terms of callus formation. A total of 150 IVC1 (in vitro culture) derived plants were maintained in the screenhouse for evaluation and selection in 2015.
• In vitro mutation (IVM) of the 3 IVC responding genotypes with different doses (0, 5, 10, 20, 30, 40 50, 60 and 70 Gy) of 60Co gamma ray, resulted in the generation of 203 IVM1 plants. The plants will be evaluated for selection in 2015.
Activity 2. Breeding Line Development
Activity 2.1 Conventional Breeding
• F1 progeny: A total of 50 crosses were made in 2014 dry season (DS) and wet season (WS). Hybridization activity in 2014 WS resulted in the generation of 440 F1 seeds from 29 crosses. The F1 population will be established in 2015 DS for F2 population generation.
• F2 progenies: In 2014 DS, 24 F2 populations were established: 7 for submergence tolerance, 13 for drought tolerance, 3 for saline tolerance and 2 for glutinous trait.
A total of 702 individual plants were selected based on phenotypic acceptability. In 2014 WS, 4 F2 populations from the following crosses, BPI76/ PSB Rc82, CHINOIS 6/ SHZ 2, PR38560-2-AZUCENA-Coll. No. 1528-M5R-2DrS 112/ SHZ 2 and PSB Rc90/ NSIC Rc194, were established, with harvested seeds per population pooled generating the F2:3 populations.
These populations will be advanced for line development in 2015 DS.
• Advanced lines (F3-F7): In 2014, 7,188 advanced lines from 102 crosses in DS, and 5,735 lines from 160 crosses in WS were evaluated (Table 51).
Activity 2.2 Doubled-haploid Breeding
• In 2014 the anther culture of 14 F2 and F1 progenies identified 9 (57.1%) responding genotypes in terms of callus formation and plant regeneration. A total of 184 R1 plants were regenerated from 3 crosses, while observation of regeneration from 6 other crosses is still in progress.
• The 74 doubled haploid lines (DHLs) derived from a single cross - PJ21/PSB Rc18, a three-way cross- PR30025-99AC- WSAL-1087/SHZ-2/Chinois 6, and 6 parent genotypes - IR31406-333-1, PR37138-1, PSB Rc82, Katsuri, Namsagui 19, PR39315 were seed increased and evaluated for agronomic traits in 2014 DS and WS. The DHLs will be evaluated further for agronomic and morphological traits, yield potential under irrigated, yield under managed drought, and for other abiotic and biotic stresses in 2015.
Activity 2.3 Mutation Breeding
• A total of 77 IVC lines derived from Salumpikit were evaluated for submergence tolerance at seedling stage. Results identified 74 (96.1%) lines with survival comparable to the tolerant check, FR13A.
• Salinity evaluation of the 74 Salumpikit-derived lines resulted in the identification of 16 (21.6%) lines tolerant (T), 40 (54.1%) moderately tolerant (MT) and 18 (24.3%) susceptible (S).
Activity 3. Field performance evaluation
• A total of 359 breeding lines were evaluated under ON irrigated and managed-drought stress condition in 2014 DS.
Under non-stress condition, 13 (8%), and 96 (56%) breeding lines yielded at least 5% higher than PSB Rc14 (7.3 t/ha) and IR64 (6.7 t/ha), respectively.
• The 195 (54%) lines selected from DS evaluation, were re-evaluated in 2014 WS under irrigated and simulated rainfed condition, identifying 5 (2.6%) lines (PR39172-B- 19-B-B-2, PR39955-B-2-1-3-2, PR40029-B-14-B-2-2-2, PR39954-B-15-1-2-2, PR41398-ICRL2008WS-PSB Rc68 34-1- 2) out-yielding the check variety NSIC Rc222 (4.324 t/ha), and 25 lines (15%) yielding higher than PSB Rc14 (3.991 t/hat/ha)
• Combining the performance of the breeding lines from the 4 trials (2014 DS: non-stress and drought stress; 2014 WS:
irrigated and simulated rainfed condition) 83 (49 %) lines were selected for inclusion in the 2015 WS Multi-Environment Trial (MET). The line selections are seed multiplied in 2015 DS.
Table 51. Breeding lines developed from crossess made in 2013 and 2014 for drought-prone rainfed lowland, PhilRice-CES, 2013 WS -2014 WS.
Filial generation
(Pedigree Nursery)
2013 WS 2014 Remarks
No. of crosses Total
no. of lines
DS WS
No. of crosses Total
no. of lines
No. of
crosses Total no.
of lines F1
Generation 25 10
F2
Generation 3 106 25 702 2
163
2 bulked bulked due to lodging F2:3
Generation 27 535
F3
Generation 43 1,006 3 201 27
680 F4
Generation 29 965 42 1,731 32
1,190* 657 lines from 2 crosses*
F5
Generation 24 2,010 29 953 47 1,815** 413 lines from 5 crosses*
F6
Generation 4 411 24 2,011 30 725*** 219 lines from 8 crosses*
F7
Generation 16 1,881 4 411 ** 24 1,325
F8
Generation 1,881
*materials from saline screening added for phenotypic evaluation
** not planted during 2014 WS, seeds were stored
Arimuram Aringay
Ballatinaw Luna Dinorado
Bukutan Gudoy
Dagmuy Enggopor
Buga Pennawid
Figure 58. Variations in hulled rice and brown rice of the traditional varieties evaluated in 2014 DS.
Note: Scale = 200 µm
Figure 58. Variations in hulled rice and brown rice of the traditional varieties evaluated in 2014 DS.
Mass Screening for Salinity, Submergence, and Seedling Stage Drought Tolerance
NV Desamero, JC Bagarra, GD Valida, EP Bulaong
An efficient and effective screening facility and protocol for abiotic stress tolerance is a key component and a must requirement for a successful rice variety improvement program. The mass screen protocol must be cost effective and must produce reliable and repeatable results. Pre-selection of breeding materials under controlled or managed condition increases selection efficiency in the target environment where the breeding lines are bred for.
Highlights:
Activity 1. Drought tolerance mass screen at seedling to early vegetative stage
• The drought screening facility was upgraded from wooden trays to galvanized iron sheet (GI) trays measuring 5 m length x 1 m width x 0.4 m depth, containing soil mix composed of garden soil and sand (1:1 by weight). The effectiveness of the new soil mix was established as reflected in the well differentiated response of the susceptible and tolerant test genotypes as well as in the homogeneity of the differential response across the length of the tray (Figure 59). The observed soil cracking in the previously used clayey paddy soil, which injures the seedling roots and results in highly non- homogeneous stress development along the tray, was solved (Figure 60).
• The drought screen of 101 entries (66 mutant lines and 35 traditional varieties [TRVs]) identified 30 (30%) potentially tolerant lines (7 tolerant, 23 moderately tolerant) (Table 52).
• Of the 10,420 plants from 14 segregating F2:3 populations, 5,687 (54%) were recovered and selected as putatively drought tolerant (Table 53). A range of 25% to 85% with an average of 54% plant recovery from drought stress was obtained. The recovered plants were grown to maturity and the F4 seeds harvested will be established in the pedigree nursery for line advancement in 2015.
Activity 2. Saline tolerance mass screen at seedling stage
• The mass screen for seedling salt tolerance of 45 breeding materials from hybrid rice development project consisting of (1) 2 A-lines (male sterile), (2) 23 B-lines (maintainer), (3) 9 restorers, (4) 2 F1 hybrids, (5) 9 parentals, classified 36 (80%)
genotypes as tolerant (T) to moderately tolerant (MT) and 9 (20%) susceptible (S) to highly susceptible (HS).
• With two F2 segregating populations, 498/680 (73.2%) plants from the cross NSIC Rc9/FL478 and 513/1160 (44.2%) plants from PSB Rc90/PSB Rc82 survived salt stress and considered putatively salt tolerant. These plants will be advanced for line development in the pedigree nursery.
• In 2014 WS, 14 out of the 27 Wagwag variants germinated and screened for salinity stress. Results showed six (6) variants (PRRI000372, PRRI002198, PRRI003405, PRRI003406, PRRI004904, and PRRI004900) were moderately tolerant to salt stress. Remaining Wagwag variants will be screened as soon as viable seeds are available.
• Also, seven (7) fixed lines (F6) selected on-farm in Cagayan (one (1) from FL378/PSBRc18-Sub1 cross, one (1) from FL478/1*PSBRc82 and five (5) from FL478/GSR 205) were screened. Results showed that plant selection from FL378/
PSBRc18-Sub1 and FL478/1*PSBRc82 were moderately tolerant and tolerant, respectively. For FL478/GSR 205 cross, 1 HT, 2 T and 2 MT from the 5 plant selections were observed.
These plants will also be advanced for line development in the pedigree nursery.
• Moreover, 11 F4 (F2:3 derived) segregating populations for sal-sub breeding were subjected to selection under salinity stress (Table 54). A total 4,720 plants wherein 515 (12%) HT, 688 (16%) T, 990 (24%) MT, 1,509 (36%) S and 483 (12%) HS were observed. Salt tolerant plants from these populations will be harvested and subjected for advance generation in-station pedigree nursery and on-site in Dingalan in 2015 WS.
Activity 3. Saline tolerance mass screen at reproductive stage
• Initial work was done using 20 Sadri tolerant lines from Iran as recommended by colleagues from IRRI, Salinas 1, Salinas 9, FL478 and IR29 as test materials in the screen at reproductive stage on September 10. The test materials were grown under non-stress (Figure 61A) and salt stress (Figure 62B, 4) condition using “water baths”. Four trays measuring 60cm (L) x 31cm (W) x 24cm (D) were used for each condition. Each tray held six pots (measuring 17cm diameter x 19cm height) containing paddy soil planted with 2 to 4 plants. During the non-stress condition, fertilizer was applied in two splits, 3 grams per pot applied as basal in the soil, and another 3g applied per
pot at panicle initiation. Salinized water with initial electric conductivity (EC) of 10.38, 8.55 pH and 30°C temperature was used to imposed stress starting at 37 days after sowing (DAS) until 94 DAS with 57 days duration of continuous salinization.
• Under non-stress condition plant height ranged from 11 to 51cm while under stress it ranged from 9 to 43cm measured 59 DAS or 22 days after salinization. Eleven (46%) had 1 cm to 29cm height reduction, while 5 (21%) entries increased their height even under stress condition. These 5 entries (SADRI 32332, SADRI 32335, SADRI 32339, SADRI 32340 and SADRI 33950) are candidate reproductive salt tolerant genotypes.
• Symptoms of salt stress injury with prolonged exposure were observed as papery panicles with sterile spikelets (Figure 65) at maturity. The susceptible variety check IR29 did not survive the imposed salt stress. The plants which survived had unfilled grains.
• Re-screening of the 5 selected SADRI lines will be done to improve the screening protocol. Improvement of the mass screen system shall allow us to identify sources of salt stress tolerance at reproductive stage. The SADRI lines will, likewise, be fully characterized.
Activity 4. Submergence tolerance mass screen at seedling stage
• Of the 116 maintainer lines, 7 (6%) MT lines with 75%-88%
mean survival surpassed the tolerant check, FR13A with 68%
mean survival. The remaining 11 (9.5%) and 97 (83.6%) lines were susceptible and highly susceptible, respectively. The tolerant lines together with 5 restorer lines will be re-validated for submergence tolerance at seedling and vegetative stage.
• The mass screen of the 3 F2 and 2 F2:3 populations, resulted in the survival of the 529 (11%) out of 4,852 segregating plants. These survivors were considered putatively
submergence tolerant plants. The selections are composed of 91/1501 (6%) plants from the cross BPI 76/Ciherang-Sub1, 109/1820 (6%) from NSIC Rc9/NSIC Rc194, 89/1052 (8%) from PSB Rc18-Sub1/NSIC Rc240//PSB Rc18/PSB Rc68, 103/235 (44%) PSB Rc18-Sub1/NSIC Rc222 and 137/244 (56%) from PSB Rc18-Sub1/NSIC Rc240 (Table 55). The putatively tolerant plants will be genotyped to confirm the presence of sub1 gene. Plants positive to the sub1 markers
(Art5 and SC3) will be planted in the pedigree nursery for agro-morphological selection and line development in 2015 WS.
Figure 59. Response of tolerant check, PSB Rc14 and susceptible check, IR64 to drought stress planted in rows side by side, consecutively, across the
entire length of the tray, 2014 DS, PhilRice-CES.
Figure 60. Soil cracking during drought development with clayey paddy soil (A) compared with soil:sand (1:1) mix with no or minimal cracking (B), 2014
DS, PhilRice CES.
Table 52. Summary of drought recovery (%) response to drought stress of stable mutant lines and traditional varieties, 2014 WS, PhilRice-CES.
No. GENOTYPE Total HT T MT S HS
n % n % n % n % n %
1 IVM-derived Salumpikit
lines 46 0 0 5 10.9 15 32.6 16 34.8 10 21.7
2 SM-derived Pokkali lines 10 0 0 1 10 5 50 2 20 2 20 3 SM-derived KDML lines 10 0 0 0 0 1 10 7 70 2 20 4 Traditional Varieties 35 0 0 1 2.9 2 6 8 22.9 24 68.6
Total 101 0 7 23 33 38
Average 0 6.0 24.7 36.9 32.6
HT, highly tolerant (score 1) = 90-100% plants recovered; T, tolerant (3) = 70-89%; MT, moderately tolerant (5) = 40-69%; S, susceptible (7) = 20-39%; HS, highly susceptible (9) = 0- 19%.
Table 53. Fourteen F2:3 populations subjected to drought stress at seedling to early vegetative stage, 2014 WS.
N
o. Cross
Initial seedlings
that emerged
Plant recovered from drought
stress
No. of plants with
seeds harvested
no. % no. % no. %
1 BPI 76/PSB Rc82 786 78.6 277 35.2 15 5.4
2 CHINOIS 6/SHZ-2 817 81.7 203 24.8 86 42.4
3 BPI Ri10/PSB Rc14 766 76.6 459 59.9 321 69.9
4 NSIC Rc222/PSB Rc68 726 72.6 381 52.5 100 26.2
5 PR25769-B-9-1/NSIC Rc17 655 65.5 287 43.8 49 17.1
6 NSIC Rc9/PSB Rc68 744 74.4 382 51.3 49 12.8
7 PSB Rc68/NSIC Rc9 754 75.4 440 58.4 72 16.4
8 HHZ 5-SAL8-DT3-SUB1/PSB Rc14 788 78.8 490 62.2 293 59.8 9 PR34363-4-Pokkali-AC-45-M5R-19 DrS
97/SHZ 5-SAL8-DT3-Sub1 717 71.7 454 63.3 125 27.5
1
0 HHZ 5-SAL8-DT3-Sub1/PSB Rc82 854 85.4 728 85.2 235 32.3 1
1 HHZ 5-SAL8-DT3-Sub1/NSIC Rc9 680 68 481 70.7 162 33.7 1
2 BPI 76/Ciherang-Sub1 830 83 515 62 193 37.5
1
3 NSIC Rc9/NSIC Rc194 632 63.2 178 28.2 151 84.8
1
4 PSB Rc18-Sub1/NSIC Rc240//PSB Rc18/PSB
Rc68 671 67.1 412 61.4 93 22.6
Total 10,42
0 5,687 1,94
4 Minimum 632 63.2 178 24.8 15 5.4 Maximum 854 85.4 728 85.2 321 84.8
Average 744 74.4 406 54.2 139 34.9
*Count of green shoots 5 days after rewatering (DARw).
Table 54. Seedling salt-stress screen of segregating F4 population* (F2:3- derived) from the sal-sub breeding study (PBD-009-005), 2014WS, PhilRice- CES (Note: Seeds harvested from plants that survived to maturity were turned over to the breeder for line advance in 2015 DS).
N
o. Glasshouse
Code Designatio
n Parentage Nu mbe
r of See ds Sow n
Numb er of Seeds Germi nated
HT T MT S HS Total
No.
of Plan ts Surv ived
Num ber of Plant s with Seeds Harv ested n
o. % n o. % n
o. % no. % n o. %
1 PR14WS_GH-
SAL13DS-001 PR42842-B- B-BiBacB
NSIC Rc160/NSIC
Rc182 40 32 1
7 53 .1 4 12
.5 7 21 .9 1 3.
1 3 9.
4 28 26
PR42842-B-
B-BiMalB NSIC Rc160/NSIC
Rc182 40 37 3
0 81 .1 5 13
.5 2 5.
4 0 0 0 0 37 33
2 PR14WS_GH-
SAL13DS-002 PR42852-B- B-BiBacB
NSIC Rc214/NSIC
Rc182 40 40 1
4 35 6 15 1
2 30 5 12 .5 3 7.
5 32 23
PR42852-B-
B-BiMalB NSIC Rc214/NSIC
Rc182 40 36 2
7 75 7 19 .4 2 5.
6 0 0 0 0 36 34
3 PR14WS_GH-
SAL13DS-003 PR42862-B-
B-BiBacB FL378/2*PSB
Rc18-Sub1 40 35 1
9 54 .3 9 25
.7 4 11 .4 1 2.
9 2 5.
7 32 31
PR42862-B-
B-BiMalB FL378/2*PSB
Rc18-Sub1 40 40 2
4 60 1
2 30 2 5 2 5 0 0 38 38 4 PR14WS_GH-
SAL13DS-004 PR42875-B-
B-BiBacB FL478/NSIC
Rc218 SR 40 36 1
4 38 .9 1
3 36 .1 6 16
.7 1 2.
8 2 5.
6 33 30
PR42875-B-
B-BiMalB FL478/NSIC
Rc218 SR 40 38 2
7 71 .1 1
1 28
.9 0 0 0 0 0 0 38 38 5 PR14WS_GH-
SAL13DS-005 PR41564-B-
B-BiBacB PSB Rc90/PSB
Rc18-Sub1 40 39 1
0 25 .6 2
0 51 .3 4 10
.3 3 7.
7 2 5.
1 34 29
PR41564-B-
B-BiMalB PSB Rc90/PSB
Rc18-Sub1 40 36 9 25 22 61 .1 3 8.
3 0 0 2 5.
6 34 34 6 PR14WS_GH-
SAL13DS-006 PR42878-B-
B-BiBacB FL478/NSIC
Rc194 40 38 8 21
.1 1 8 47
.4 1 1 28
.9 0 0 1 2.
6 37 33
PR42878-B-
B-BiMalB FL478/NSIC
Rc194 40 39 2
3 59 1 2 30
.8 4 10
.3 0 0 0 0 39 36 7 PR14WS_GH-
SAL13DS-007 PR41563-B-
B-BiMalB FL478/NSIC
Rc160 40 39 2
5 64 .1 1
3 33
.3 0 0 0 0 1 2.
6 38 38
Figure 61. A) Non-stress and B) saline stress screen at reproductive stage, 59 DAS and 22 days after salinization, respectively, PhilRice-CES, 2014 WS.
Figure 62. Comparative plant height of Sadri 32334 under stress (left) and non-stress (right) condition.
Figure 63. Panicle coming out from the leaf sheath with papery (unfilled) spikelets, indicative of salt stress injury.
Table 55. Segregating populations screened for submergence at seedling stage in cemented tank, PhilRice CES.
Generat
ion Cross
No. of plants before submergenc
e
Plants/population (No.) Surviv
ed % Seeds
harvest
ed %
F2
PR45822 BPI 76/Ciherang-Sub1 1501 91 6 89 6
PR45814 NSIC Rc9/NSIC Rc194 1820 110 6 110 6
PR45826 PSB Rc18-Sub1/NSIC
Rc240//PSB Rc18/PSB Rc68 1052 92 9 92 9
F2:3*
PR45142 PSB Rc18-Sub1/NSIC Rc222 235 103 44 70 30
PR45143 PSB Rc18-Sub1/NSIC Rc240 244 137 56 77 32
Total 4852 529
10.9 438 83
* 147 plants for DNA analysis using SC3 and ART5 this 2015 DS.
Mass Screening for Reproductive Stage Drought Tolerance
TA Sigari, JM Niones, VAC Marcelo, MAR Orbase, MV Chico, JC Bagarra, NV Desamero
Drought stress is a major abiotic constraint in rainfed rice especially in the reproductive stage when even moderate stress can cause significant yield reduction or total yield loss. In the ARMM region, 73.92% of the area where rice is harvested is rainfed whereas in the Visayas, approximately 32% is also rainfed (BAS, 2015), In addition, the irrigated ecosystem’s administration mostly run-off-the river type, which make the 35% to 45%
irrigated rice areas similar to rainfed conditions during the dry cropping season. Breeding for resistance to drought is complicated by the lack of fast, reproducible screening techniques and the inability to routinely create defined and repeatable water stress conditions where large populations can be evaluated efficiently (Ramirez and Kelly, 1998). The success of any breeding program depends not only on the genetic variability of the crop, but is also equally important, on the reliable evaluation, screening and selection facility and methodology for the targeted traits under a reliable selection environment representing the target population environment. Thus, the screening of advanced lines under adequate water supply, rainfed and managed drought environments within each year may provide opportunities to reduce number of years required for selection of rice lines for adaptation in a rainfed lowland ecosystem.
Highlights:
• A total of 554 test entries selected from F8 segregating and observation nurseries were used in mass screening for drought at reproductive stage in 2014 wet season (WS) and dry season (DS). In 2014DS, 359 test entries (with 4 check varieties were
evaluated under managed drought-rewatering-drought at reproductive stage. In 2014WS, 195 test entries selected from DS were validated under rainfed and irrigated conditions.
• In DS, two cycles of drought was imposed, 1st cycle of drought was imposed at 30 days after transplanting (DAT) for 28 days, and then the field was re-watered at 2 to3 cm water level for 2 days. The 2nd cycle of drought lasted for 20 days and again re-watered when the IR64 susceptible check variety 100% leaf rolled in response to stress.
• Soil hydrology (water table depth (WTD), rainfall, gravimetric soil moisture content (SMC) at 2 soil depths (1) 0 to 15cm and (2)15 to 30cm soil depths were obtained in the drought- stressed trial, % SMC at (1) soil depth was reduced from 32%
to 30% while % SMC was heighten from 20% to 24% in (2) soil depth, during the1st cycle of drought. The decrease in SMC was attributed to the declined in WTD from 49cm to 114cm above the soil surface (Figure 64). At 25 days after drought imposed (DADI), IR64 (susceptible check) genotypes showed a symptom of leaf rolling while PSB Rc14 (tolerant check) leaf rolled (1, SES) at 27 DADI. At the end of 1st drought, 80.8% of the entries showed tolerance to drought (leaf score > 5, SES).
In the 2nd cycle of drought stress, the % SMC declined from 34% to 15% at surface (1) and from 32% to 22% in (2) soil depth with the 20 days drought stress duration.
• The days to 50% heading ranged from 78 to 122 days after sowing (DAS), plant height ranged from 48cm to 93cm, tiller numbers ranged from 5-39 tiller per plant; panicle number ranged from 1 to 27 panicle per plant. The mean grain yield ranged from 0.007t/ha to 2.766t/ha with an average of 0.408t/
ha whereas the yield of check varieties ranged from 0.151t/ha (IR64) to 0.940t/ha (NSIC Rc192).
• Yield reduction of test entries ranged from 53-100% while check varieties ranges from 79 to 108%.The computed STI indicated 56 (0.001-0.544) test entries had comparable or higher STI than the drought tolerant check PSB Rc14 (0.114).
Based on yield performances under drought stress, 41 (11%) test entries have yield higher 1.0t/ha, while 6 test entries had yields of ≥ 2.0 t/ha (2.301 to 2.766 t/ha). Meanwhile, 35%
of the test entries showed at least 5% yield advantage of the population yield means (0.411t/ha). On the other hand, 31 (9%) of the entries were selected based on advantage of population mean, % yield reduction (61 to 90%), STI (0.147-
0.544), delay in flowering (2 to 10 days) and leaf drying score.
• In favorable condition across entries, breeding lines matured ranged from 105 to 131 DAS and with the yield ranged of 1.128t/ha to 8.684t/ha. Nineteen (11%) breeding lines have selected for 5% yield advantage than the populations mean (6.875t/ha). 13 (8%) breeding lines showed 5% yield advantage compared to PSB Rc14 (7.3t/ha) and 96 (56%) breeding lines have 5% yield advantage than IR64 (6.7t/ha).
Out of the 359 entries evaluated, 171 entries were selected to have good drought performance and stable yields under both conditions, these entries were further evaluated in WS trial for rainfed and irrigated condition.
• In 2014WS, the test entries showed high significant effect in grain yield under favorable condition. These breeding lines flowered from 78 DAS to 99 DAS, plant height from 89 cm to 135 cm, productive tillers from 9 to 14, and grain yield from 0.708t/ha to 5.134t/ha. IR64 yielded 3.448t/ha, PSB Rc14 had 3.510t/ha, and NSIC Rc222 had 3.981t/ha. Five breeding lines out-yielded the check variety NSIC Rc222 (4.324t/ha), and 25 lines (15%) had yield higher than the PSB Rc14 (3.991t/ha).
Of the 195 entries, 24 (12%) were identified to have higher yield advantage (> 5t/ha) over population mean under both irrigated and rainfed conditions, good phenotypic acceptability and agro-morphological characteristics. The top sensitive genotypes were PR39172-B-19-B-B-2 (ON25), ICRL-171 (ON119), ACRL-2012WS-66-1 (ON181), Salumpikit (ON142), PR39289-B-22-B-3-1-2 (ON92) and PR40029-B-20-1-7-1 (ON85) (Figure 65), these genotypes for each sector showed the highest yield for the particular environments
• Stability and mean performance of genotypes are important to determine cultivar evaluation. The average tester axis that passes through the biplot origin and the average tester determine the rank of the genotypes based on the projection of the arrow head pointing to the greater genotype main effect. Stability of the genotypes is based on its projection into the vertical axis. The smaller the length of the projection of the genotype, the more stable the said genotypes. Salumpikit (ON142) had the lowest yield (Figure 66). Based on instability score, ICRL-131 (ON111) and ICRL-145 (ON114) are the most stable genotypes with the values of 0.017 and -0.007 respectively. The correlation between the measured or genotype mean effects and the projections are 0.959. The average genotype which is indicated by a small circle it is also