Abstract
Salinity is the major factor reducing crop yield in coastal areas of Bangladesh. Proline (Pro) application with suitable crop varieties having higher yield potential could contribute to the improvement of crop production in saline areas. The main objective of this study was to investigate the mitigation of adverse effects of salinity in aman rice by exogenously applied Pro. The experiment was carried out at the farmer’s field of Batiaghata, Khulna. Characteristically, the soil was silty clay loam having pH 6.7, EC 4.6 dS m–1, CEC 23 meq/100 g soil, organic matter 0.71%. Rice (Oryza sativa L.) variety BR23 was used as plant material. The experiment was laid out in a randomized complete block design with three replications. There were different treatment combinations namely control (no Pro), 25 mM Pro at seedling stage, 25 mM Pro at vegetative stage, 25 mM Pro at seedling and vegetative stages, 50 mM Pro at seedling stage, 50 mM Pro at vegetative stage, 50 mM Pro at seedling and vegetative stages, 100 mM Pro at seedling stage, 100 mM Pro at vegetative stages, and 100 mM Pro at seedling and vegetative stages. Recommended doses of N, P, K, S and Zn fertilizers were applied to the all experimental plots. Thirty-day-old seedlings were transplanted in the experimental plots. Proline solutions were sprayed over plant leaves with the help of sprayer as per treatments. Salinity caused significant reductions in growth and yield of BR23 by decreasing plant height, number of effective tillers, panicle length, filled grains panicle-1 and 1000-grain weight. On the other hand, exogenous application of Pro showed a significant increase in growth and yield of BR23 under saline conditions. Results also revealed that growth and yield of rice did not increase proportionally with the increasing doses of Pro. Proline application resulted in significant increases in K+/Na+ and nutrient uptake by rice under salinity. The present study suggests that exogenous application of Pro confers tolerance to salinity in aman rice by increasing K+/Na+ ratio and nutrient uptake.
 J. Bangladesh Agril. Univ. 17(2): 194–199, June 2019
Highlights
In salinity prone areas of the world
It was observed that there were no significant variations in panicle length among the treatments that exposed varying concentration of Pro application such as 25 mM, 50 mM, 100 mM Pro at seedling stage, vegetative stage, and both seedling and vegetative stages
Exogenous application of Pro with suitable crop varieties having higher yield potential could contribute to the improvement of crop production in saline condition
Summary
In salinity prone areas of the world. About 20% of world’s cultivated areas and nearly half of the world’s irrigated lands are affected by salinity (Mali et al, 2012). Salinity effects are more conspicuous in arid and semiarid regions where limited rainfall, high evapotranspiration and high temperature associated with poor water and soil management (Azevedo et al, 2006; Jaleel et al, 2008). Agricultural productivity is severely affected by soil salinity, and the damaging effect of salt accumulation in agricultural soils has become an important environmental concern (Jaleel et al, 2007). Rice is mainly grown in salinity affected areas of Bangladesh but the average yield is very low due to lack of salt-tolerant high yielding variety and inappropriate management. In Bangladesh, out of 2.85 million hectares of reach 6 to 9.3 billion by the year 2050 whereas the crop the coastal and off-shore areas, about 1.06 million production is decreasing rapidly because of the negative hectares are affected by salinity (SRDI, 2010). Proline is one of the major osmoprotectant osmolytes, which is synthesized
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