EFFECT OF TEMPERATURE AND PHOTOTHERMAL QUOTIENT ON THE YIELD COMPONENTS OF WHEAT (Triticum aestivum L.) IN INDO-GANGETIC PLAINS OF INDIA

SUMMARY To quantify the effect of thermal stress and photothermal quotient (PTQ) on yield components, eleven years experimental data of three cultivars (HD-2285, K-8804 and K-9107) under three sowing dates at Kanpur centre were analysed. Number of grains per ear (NG), grain weight per ear (GW) and 1000-grain weight (TG) were identified as prime yield contributing components in HD-2285, K-8804 and K-9107, respectively. GW was highly sensitive to maximum temperature (MXT) while NG was sensitive to minimum temperature (MNT) during jointing (JNT) to anthesis (ATS) as well as the total growing season in all the cultivars. In both HD-2285 and K-8804, optimum MXT and MNT during JNT to ATS are 22.7–24.6 and 7.0–7.9 °C, respectively for obtaining maximum NG. Optimum MXT for GW ranged from 15.8–17.3 °C during tillering (TLR) to JNT stage in K-8804 and K-9107 while it was 20.4 °C during JNT to ATS stage in HD-2285. MXT, MNT and PTQ of 23.6 °C, 9.2 °C and 25 MJ/m 2 /day/ °C, respectively during JNT to ATS in K-9107 were found optimum for higher TG.