Heat tolerance for yield and its components in different wheat cultivars
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Twenty one diverse, standard and experimental cultivars of common spring wheat (Triticum aestivum L.) were tested for the effect of heat stress on phenology, yield and its components by growing the materials for 2 years under full irrigation during the hot summer (offseason), and the cool winter (normal) conditions. Heat tolerance was estimated for each variable by the ‘heat susceptibility index’ (S) which scales the reduction in cultivar performance from cool to hot conditions relative to the respective mean reduction over all cultivars.
Genotypes differed significantly in S for yield and its components. The ranking of cultivars in S over the 2 years was consistent for yield, kernels per spike and kernel weight, but not for spike number. Of the three yield components, the greatest genotypic variation in S was expressed for kernels per spike. However, S for yield could not be simply attributed to S in a unique component across all cultivars. On the other hand, a general linear model regression of summer yield on its components revealed that the most important yield component affecting yield variation among cultivars under heat stress was kernel number per spike. Kernel number per spike was positively associated across cultivars with longer duration and greater stabilty of thermal time requirement from emergence to ‘double ridge’. It is therefore concluded that kernel number per spike under heat stress is a reasonable estimate of heat tolerance in yield of wheat and that this tolerance is operative already during the first 2 to 3 weeks of growth.
Key wordsTriticum aestivum wheat heat tolerance phenology yield components selection
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- Berry, J. & O., Bjorkman, 1980. Photosynthetic response and adaptation to temperature in higher plants. Ann. Rev. Plant Physiol. 31: 491–532.Google Scholar
- Blum, A., 1970. Nature of heterosis in grain production by the sorghum panicle. Crop Sci. 10: 28–31.Google Scholar
- Blum, A., 1986. The effect of heat stress on wheat leaf and ear photosynthesis. J. Exp. Bot. 37: 111–118.Google Scholar
- Dawson, I.A., & I.F., Wardlaw, 1989. The tolerance of wheat to high temperatures during reproductive growth. III. Booting to anthesis. Aust. Jour. Agric. Res. 40: 965–980.Google Scholar
- Fischer, R.A. & R., Maurer, 1978. Drought resistance in spring wheat cultivars. I. Grain yield responses. Aust. J. Agric. Res. 29: 897–907.Google Scholar
- Kuroyanagi, T. & G.M., Paulsen, 1985. Mode of high temperature injury to wheat. II. Comparisons of wheat and rice with and without inflorescence. Physiol. Plant. 65: 203–208.Google Scholar
- Midmore, D.J., P.M., Cartwright & R.A., Fischer, 1984. Wheat in tropical environments. II. Crop growth and grain yield. Field Crops Res. 8: 207–227.Google Scholar
- Rawson, H.M., 1986. High-temperature tolerant wheat: a description of variation and a search for some limitations to productivity. Field Crops Res. 14: 197–212 1155.Google Scholar
- Rijven, A.H.G., 1986. Heat inactivation of starch synthase in wheat endosperm. Plant Physiol. 81: 448–453.Google Scholar
- Shpiler, L. & A., Blum, 1986. Differential reactions of wheat cultivars to hot environments. Euphytica 35: 483–492.Google Scholar
- Sigh, V.P., M., Singh & M.S., Kairon, 1984. Physiological maturity in aestivum wheat: visual determination. J. Agric. Sci. Camb. 102: 285–287.Google Scholar
- Wardlaw, I.F., I.A., Dawson & P., Munibi, 1989. The tolerance of wheat to high temperature during reproductive growth. II. Grain development. Aust. Jour. Agric. Res. 40: 15–24.Google Scholar
- Warrington, I.J., R.L., Dunstone & L.M., Green, 1977. Temperature effects at three development stages on the yield of the wheat ear. Aust. J. Agric. Res. 28: 11–27.Google Scholar