the Symposium on Wheats for More Tropical Environments - cimmyt

107Breeding Wheats for Heatand Drought Tolerance in Central IndiaY.M. Upadhyaya and K.N. Ruwali, Indian Agricultural ResearchInstitute, Indore, IndiaAbstractCondtttonsfor wheat cultivation in central India impose severe drought andtemperature stress. High temperatures at sowing time (32 to 35°C) and atmaturity (30 to 35°C) cause defective germination and grain dehydration.respectively; frost at ear-emergence stagefrequently causes 50 to 100% loss inyield. In breedingfor drought tolerance in India. local cultivars have beenutilized; disease resistance. which is also very important. is introduced at <strong>the</strong>same time. The cultivars C306. Sujata. Hy65. NI5439. N59. A9-30-1 andMeghdoot have been developed. and genetic improvement has been madeforcharacters. such as number ofears per plant. grain weight per spike and 1000­grain weight. From about 300 cultivars testedfor temperature tolerance. sevenpossess good tolerance and comparefavorably with Hindi 62; <strong>the</strong>se alsoincorporate resistance to rusts and leaf blight. Some of <strong>the</strong> cultivars. such asH11011. H11012. Raj 1771 and Raj 1777. have proved to be promisingfor heattolerance. Afew lines. recently receivedfrom CIMMYT. also appear to bepromising. Encouraging results have been obtainedfrom spring x Winter crossesand will befur<strong>the</strong>r exploited.In Central India. stresses of droughtand temperature affect wheatcultivation, under both rainfed andirrigated conditions (Figure 1). Soilmoisture at seeding depth is directlyrelated to germination, and temperaturealso plays a major role. The relationshipis shown in Table 1.50456o 40';35'"'.330e25Q)S20~ 1510Max. temp.5 L_~==~~~~~~e!:!=~i!::L.r--Sept. Oct. Nov.o Rain once in 5 yearsCJSoWing periodE;ZJFrost-prone periodDec. Jan. Feb. Mar.• Rain twice in 5 yearsDEar-emergence period~MaturityperiodFigure 1. Weatber conditions for tbe wbeat-crop season, Indore, India.1979 to 1984