~ 295 ~ The Pharma Innovation Journal 2018; 7(9): 295-300 ISSN (E): 2277- 7695 ISSN (P): 2349-8242 NAAS Rating: 5.03 TPI 2018; 7(9): 295-300 © 2018 TPI www.thepharmajournal.com Received: 24-07-2018 Accepted: 26-08-2018 Argha Ghosh Department of Agricultural Meteorology and Physics, Bidhan Chandra Krishi Viswavidyalaya, West Bengal, India Mousumi Malo Department of Agronomy, Bidhan Chandra Krishi Viswavidyalaya, West Bengal, India Sushanta Sarkar Department of Agricultural Meteorology and Physics, Bidhan Chandra Krishi Viswavidyalaya, West Bengal, India Safiuddin Ahmed Khan Department of Agricultural Meteorology and Physics, Bidhan Chandra Krishi Viswavidyalaya, West Bengal, India Correspondence Argha Ghosh Department of Agricultural Meteorology and Physics, Bidhan Chandra Krishi Viswavidyalaya, West Bengal, India Crop growth analysis of grass pea in relation to thermal condition in new alluvial zone of West Bengal Argha Ghosh, Mousumi Malo, Sushanta Sarkar and Safiuddin Ahmed Khan Abstract In order to study the effect of thermal condition on crop growth of grass pea, field experiment was conducted during Rabi season of 2016-2017 at the Instructional Farm, Bidhan Chandra Krishi Viswavidyalaya, West Bengal. The experiment was carried out in Randomized Complete Block Design with nine treatments (nine dates of sowing starting from 26 th October to 21 st December at weekly interval). Crop sown on 16 th November produced highest leaf area index at 42 DAS (0.56), 63 DAS (0.89) and at the time of harvest (1.39). During 63 DAS to 84 DAS, crop growth rate was positively correlated with maximum, minimum and average air temperatures (r = 0.70*). Diurnal temperature difference during 63 DAS to 84 DAS showed harmful effect on relative growth rate (r = -0.69*) while during 84 DAS to harvest, diurnal temperature difference showed significant positive effect on NAR (r = 0.67*). The influence of temperature and thermal indices on crop growth parameters varied as growth stages and sowing dates changed. Keywords: Crop growth, correlation, grass pea, temperature, thermal utilization Introduction Yield of crops is actually the results of the effects of various environmental factors (Krishna Murthy and Yogeswara Rao, 2000) [12] . Temperature played an important role in crop growth and biomass production (Hatfield and Prueger, 2015) [9] . Under the context of climate change rising minimum air temperature affects crop growth and yield to a greater extent (Hatfield et al., 2011) [8] . Crop growth attributes such as leaf area index (LAI), leaf area duration (LAD), crop growth rate (CGR), relative growth rate (RGR), net assimilation rate (NAR) are positively correlated with the final yield of the crop. Indirect effect of temperatures on crop growth can be shown by temperature based agrometeorological indices viz. Growing degree day (GDD), Heliothermal unit (HTU) and Photothermal unit (PTU). These thermal indices are used for prediction of growth and yield of various crops (Tzudir et al., 2014) [28] . Influence of delayed sowing and thermal condition on growth and yield of crops can be determined through accumulated heat unit system (Bishnoi et al., 1995) [5] . Crop growth may be analyzed by studying agro-meteorological indices accumulated during crop growing period and their utilizations (Benbi, 1994 and Singh et al., 1996) [3, 26] . Grass pea (Lathyrus sativus L.), commonly known as, chickling pea, chickling vetch, Indian pea etc. is an important grain legume cultivated in India during winter season. It is a rich source of protein (28%) andminerals especially calcium, phosphorus and iron (Bhagat et al., 2015) [4] . The present study was carried out to determine the variation in crop growth due to alteration of sowing time. Materials and methods Details of the experiment Field experiment was conducted during the winter season of 2016-2017 at the Instructional Farm (2258´ N, 8831´ E and 9.75 m above mean sea level), Bidhan Chandra Krishi Viswavidyalaya, West Bengal, India, with grass pea (cv. ‘Prateek’), sown on nine different dates (26 th October, 2 nd November, 9 th November, 16 th November, 23 rd November, 30 th November, 7 th December, 14 th December and 21 st December). Experiment was carried out in Randomized Complete Block Design with three replications with three replications. 40 kg/ ha seed rate was followed and 30 cm of row to row spacing was maintained. All the recommended management practices for this area were followed.