the Symposium on Wheats for More Tropical Environments - cimmyt

109unit area. However, looking at some of<strong>the</strong> yield components. <strong>the</strong>re has been'improvement in <strong>the</strong> number of ears perplant in A9·30·1 and Hy65 and in grainnumber per ear and grain weight perear in A9-30-I. Hy65 and C306; testweight has been improved in Meghdoot,Hy65 and C306.Screening and Evaluationfor Temperature ToleranceDuring <strong>the</strong> past six years. more than300 varieties from different breedingstations have been screened at anumber of centers over differentlatitudes (12 to 31 ON) and longitudes(74 to 84°E). Sowing was done fromSeptember 20th until December anddata such as germination, productiveears. grain yield and l000-grain weightwere collected. Maximum temperaturesranging from 30 to 35°C. andminimum temperatures of 10 to 21°Cwere encountered. It was observed that<strong>the</strong> varieties showed very poorgermination before October 20th. and<strong>the</strong>n improved until November 15th;after that date germination againdecreased. The number of days to earemergence was profoundly influencedby latitude and prevailingtemperatures. Heading took 50 to 75days at Dharwar (12°N), 60 to 90 daysat Niphad (20 0 N). 65 to 100 days atIndore (22°N) and 100 to 125 days atGurdaspur (31 ON). With early SOWing,emergence was delayed. Phenologicalstudies revealed that varieties whichflowered very early had better yield inpeninsular India. and those floweringmid-late were best adapted in <strong>the</strong>central region. Late types, with 105 to115 days to ear emergence. weresuperior in <strong>the</strong> north. The prostratecharacteristic combined with thinnarrow leaves during tillering andnarrow. semi-erect leaves on <strong>the</strong> stemswere desirable. This reduced direct soilmoisture evaporation andevapotranspiration losses from <strong>the</strong>plants. An adverse effect of late sowingon kernel development has beenobserved. In early October sowings.Table 2. Genetic improvement shown by improved cultivars compared to local cultivarsunder stress conditions, India, 1974 to 1977§No. of No. of Yield No. of No. of Grain weight! 1000-grainCultivar seedlings/m2 ears/m2 (g/m2) ears/plant grains/ear ear (g) weight (g)Durum wheatsKathia (local) 195 287 227 1.5 20.1 0.79 49.3Malvi (local) 197 272 242 1.4 19.2 0.89 49.1Meghdoot 152 208 184 1.4 17.5 0.88 54.1(100) (91) (99) (110)Arnej (local) 245 266 279 1.1 20.6 1.05 45.6A9-30-1 180 261 320 1.5 32.7 1.23 41.8(136) (159) (117) (92)Bread wheatsPssi (local) 215 304 233 1.4 15.9 0.77 41.2HY65 141 246 217 1.7 20.4 0.86 42.7(121) (128) ( 112) (104)C306 154 209 228 1.4 18.1 1.09 45.0(100) (118) (142) (109)!.f Numbers in brackets = percent of local