Production and survival of tillers of wheat and their contribution to yield

Abstract

SUMMARYThe effect of sowing date and nitrogen on tillering patterns, survival and contribution of reproductive tillers to grain yield of standard and Mexican wheat cultivars were studied for two seasons.Maximum number of tillers/plant, 3·2–4·5, was observed after 40 and 27 days from sowing for 1970–1 and 1971–2 respectively. The number of ears/plant was 1·4 at the end of the growing season. Varieties differed in tillering, and LRN10 and Giza 155 produced more reproductive tillers than Falchetto and Mexipak. Nitrogen application increased tillering efficiency, i.e. ratio of fertile to total tillers produced. Only 26% of tillers appearing in the axil of the first true leaf (T1) and 10% of tillers in the axil of the second true leaf (T2) survived to produce ears. The high mortality of tillers was attributed to high air temperature prevailing during the growth period (33 °C by day; 18 °C by night). Eared tillers did not die and were self supporting because of the photosynthesis by the ear.Grain weight/tiller was positively correlated with tiller dry weight at heading, r= 0·76–0·96. Main shoots contributed about 81% of the total grain yield and 19% came from T1 and T2 tillers.