A field experiment was conducted to determine the sensitivity of wheat to water stress and changes in water relations and yield of wheat (Triticum aestivum L.) under water stress conditions applied at different growth stages. The experiment comprised of two wheat cultivars and four water stress treatments, maintained by withholding water at tillering, anthesis, and at both stages. Water stress caused reduction in leaf relative water contents, water potential, osmotic potential, turgor potential, growth and yield components of both the wheat cultivars. The results indicated that high value of relative water contents were associated with increased yield and yield components. Consecutive stresses at both growth stages caused severe reduction in yield and yield components in both cultivars of wheat. Keywords: Water stress; water relations; growth; Triticum aestivum; yield components. DOI: http://dx.doi.org/10.3329/bjar.v36i3.9264 BJAR 2011; 36(3): 455-468

Limited water availability hampers the sustainability of crop production. Exogenous application of glycinebetaine (GB) and salicylic acid (SA) has been found very effective in reducing the adverse effects of water scarcity. This study was conducted to examine the possible role of exogenous GB and SA application in improving the growth and water relations of hybrid sunflower (Helianthus annuus L.) under different irrigation regimes. There were three levels of irrigation, viz. control (normal irrigations), water stress at budding stage (irrigation missing at budding stage) and water stress at flowering stage (FS) (irrigation missing at FS). GB and SA were applied exogenously at 100 and 0.724 mm respectively, each at the budding and FS. Control plants did not receive application of GB and SA. Water stress reduced the leaf area index (LAI), leaf area duration (LAD), crop growth rate (CGR), leaf relative water contents, water potential, osmotic potential, turgor pressure, achene yield and water use efficiency. Nevertheless, exogenous GB and SA application appreciably improved these attributes under water stress. However, exogenous GB application at the FS was more effective than other treatments. Net assimilation rate was not affected by water stress as well as application of GB and SA. The protein contents were considerably increased by water stress at different growth stages, but were reduced by exogenous GB and SA application. The effects of water stress and foliar application of GB were more pronounced when applied at FS than at the budding stage. Moreover, exogenous GB application was only advantageous under stress conditions.

A field experiment was conducted to study the response of two maize hybrids to external K application under saline field conditions (ECe 5.71-8.91 dS m-1). The data showed that there was an increase in the different growth and yield components with the increase in the external K. The increase was more pronounced when K was applied at the rate of 175 kg ha-1 with respect to control treatment. The enhanced growth and yield of these hybrids under saline conditions might be due to the response of K application, resulting in reduced Na uptake. The results indicated that the hybrids Pioneer 32B33 perform better than Dekalb 979 and economical yield can be obtained when potassium was applied at the rate of 125 kg ha-1.

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INTRODUCTIONSalinity stress reduces the plant growth productivity and efficiency of crops around the world (Machado & Serralheiro, 2017) and affects more than 800 million ha of land in the world which is equal to 6% of the whole world (FAO, 2011). Crops grown on salt affected areas undergo high osmotic stress, ionic toxicities, poor physical conditions of soil and decreased production (Shrivastava & Kumar, 2015). Salinity is one of the major environmental issue influencing plant development and efficiency (Ahanger et al., 2017;Allakhverdiev, Sakamoto, Nishiyama, & Murata, 2000). It has been estimated that in salinity stressed soils, the concentration of Na + and Clis higher accompanied with the decreased concentration of K + and K + : Na + ratio thus adversely affecting the plant growth (Saqib, Akhtar, & Qureshi, 2004). Salt stress affects plant ARTICLE INFO