Thermal and radiation effect studies of different wheat varieties in Chhattisgarh plains zone under rice-wheat cropping system

Abstract

Field experiment was conducted during Rabi seasons of 2010-11, 2011-12 and 2012-13 at Research and Instructional Farm of Indira Gandhi Krishi Vishwavidyalaya, Raipur to examine and study the phenology, accumulation of growing degree days (GDD), heliothermal units (HTU), photothermal unit (PTU) and performance of wheat (Triticum aestivam L.) of four wheat varieties grown under five different sowing dates in factorial Randomized Block Design. It was observed that GDDs got reduced significantly with subsequent delay in sowing time. For our study purpose and as per package of practices, 25 November D₁ can be taken as early sowing and D₂ - 5 December as timely sowing conditions.  The wheat varieties Amar and Sujata took highest GDD, HTU and PTU to maturity.  On the mean basis the variety Kanchan produced highest grain yield (3147 kg/ha) followed by GW-273 (2947 kg/ha).  The significant reduction in grain yield was recorded when sowing was delayed beyond D₂ - December 05.  Among the wheat varieties Kanchan showed better performance in terms of RUE followed by GW-273 and Sujata. Highest HUE was observed in wheat variety Kanchan followed by Sujata and GW-273. Varieties giving higher yield, RUE and HUE are identified under varying growing environments so as to suggest the appropriate sowing dates of wheat varieties in Chhattisgarh plains. GDD is giving consistent results as its variability is least varying between 3.4-5.3 per cent for different varieties and therefore it is reliable index for studying environmental effects on wheat in this region. Lowest RUE was observed under 5 January sowing (D₅) in the all varieties which leads to conclusion that this sowing date must be avoided and wheat crop sowing must be completed latest by 25 December to avoid adverse effects on productivity.