An experiment was conducted during rabi seasons of 2002-03 and 2003-04 to quantify the light interception and radiation use efficiency for three wheat varieties as affected by variable number of irrigations with the combination of three wheat varieties viz., HUW-234, HD-2285 and PBW-154. The light interception increased successively till 90 days after sowing (DAS) and thereafter a gradual decrease was observed till maturity of the crop. Four irrigations given at CRI, late tillering, late jointing and ear head formation stages showed highest radiation interception followed by three and two irrigations, however, the lowest radiation interception was observed for wheat crop receiving one irrigation only. On an average, 19.08 % and 12.79 % increase in radiation interception was found for wheat crop irrigated four and three times respectively as compared to singly irrigated crop. Highest radiation interception was recorded with HUW 234 followed by HD 2285 at all the growth stages except 15, 30, 45 DAS. More light interception reflected in significantly superior yield and yield attributes in the order of I4>I3>I2>I1. Subsequently, radiation useefficiency (RUE) also followed the similar trend showing highest and lowest RUE with four and one irrigation respectively. Among the different varieties, HUW-234 recorded highest radiation use efficiency followed by HD-2285. The average RUE during the entire growing period for HUW-234 and HD-2285 was found to be 1.68 g MJ-1 and 1.63 g MJ-1 respectively, which was 4.83 and 1.95 % higher than PBW-154.

CERES-Wheat model (DSSAT v 4.5.0.0) was used to analyze the effects of rise in intra-seasonal temperature on productivity of wheat and to optimize sowing time for mitigating the effects of rise in intraseasonal temperature at seven wheat growing locations representing different zones of India. The results showed that the temperature rise had differential effect on wheat yield in different zones and also with dates of sowing. Central zone(Udaipur and Raipur) was the most susceptible (yield reduced upto 10.2%) to the rise in temperature by 3.0°C from normal. The Northern hills (Palampur) zone was least susceptible. At Palampur, wheat yield increased upto 4.07% with rise in temperature by 3.0°C from normal during early phases of crop growth while during later phases of crop growth the yield decrease was 3.46-5.79%. The temperature during first fortnight of February was most critical to wheat productivity. However in Northern hills zone, second fortnight of March was most critical as during this period the above normal temperature caused a reduction in productivity of wheat.

A field experiment was conducted during rabi (winter) season of 2004-05 and 2005-06 to study the heat and radiation use of chickpea cultivar in sandy loam soil at Faizabad,(Uttar Pradesh, India). The experiment consisted of three sowing dates viz sowing on Oct 20, Nov 05 and November 20 with four varieties viz. K-850, Awarodhi, Uday and Radhey. Results revealed that sowing on Nov 05 produced significantly higher yield attributes as well as related higher heat and radiation use efficiencies. The dry matter accumulation and number of branches/plant were higher in K-850 followed by Radhey while their lower values were obtained in Uday variety of Chickpea. Day temperature was highly correlated (R2=0.79) with dry matter than night temp. (R2=0.68). Highest dry matter was recorded at day temperature 29.4 oC, night temp. 22.4 oC and average temp. 25.9 oC.

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