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A b s t r a c t. Soil temperature is an important factor in biogeochemical processes. On-site monitoring of soil temperature is limited in spatio-temporal scale as compared to air temperature data inventories due to various management difficulties. Therefore, empirical models were developed by taking 30-year long-term (1985-2014) air and soil temperature data for prediction of soil temperatures at three depths (5, 15, 30 cm) in morning (0636 Indian standard time) and afternoon (1336 Indian standard time) for alluvial soils in lower Indo-Gangetic plain. At 5 cm depth, power and exponential regression models were best fitted for daily data in morning and afternoon, respectively, but it was reverse at 15 cm. However, at 30 cm, exponential models were best fitted for both the times. Regression analysis revealed that in morning for all three depths and in afternoon for 30 cm depth, soil temperatures (daily, weekly, and monthly) could be predicted more efficiently with the help of corresponding mean air temperature than that of maximum and minimum. However, in afternoon, prediction of soil temperature at 5 and 15 cm depths were more precised for all the time intervals when maximum air temperature was used, except for weekly soil temperature at 15 cm, where the use of mean air temperature gave better prediction.

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Abstract:The environmental stress such as salinity of soil or water is serious threat for field crops in the world, especially in arid and semiarid regions. To study salinity stress on jute (Corchorus capsularis), an experiment was laid out in factorial randomized block design keeping nine capsularis varieties (JRC-698, JRC-321, JRC-517, JRC-7447, JBC-5, JRC-212, JRC-80, JRC-532 and UPC-94) as one factor and four levels of salt concentrations i.e. control (Distilled H 2 O), 100, 160, 240 and 300 mM NaCl with three replications. Adverse effect of salinity increased with increasing concentration of sodium chloride. Among nine jute varieties the highest germination percentage (89.5%), root length (0.6 cm), shoot length (1.2 cm), fresh weight (93 mg) and dry weight (9.5 mg) of seedling were observed in 'JRC-698' at salt concentration at 160 mM NaCl as compared with other salt concentration. All growth parameters were recorded higher in control than other treatments. All growth parameters were decreased up to 240 mM NaCl concentration and it was completely inhibited at 300 mM NaCl. Variety 'UPC-94' was the most susceptible to salinity stress. Hence, white jute varieties, JRC-698 and JRC-517 can be grown at 160 mM NaCl concentration.

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