Interactive effect of salinity and potassium on cell membrane stability and related physiological processes in wheat (Triticum aestivum L.)
2002
Sultana, Z.
The research was carried out to explore the interactive effect of salinity and potassium on cell membrane and related physiological processes in four wheat (Triticum aestivum L.) varieties i.e. Pavon, Inqlab, lqbal and MH-97. The experiment consisted of 64 pots, containing 5 kg soil in each, having EC, 0.85 dSm-1 and pH 7.75. The salinity (NaCl salt) treatments i.e. 1 and 10 dSm-1 were developed and two K+ treatments i.e. 0 and 100 kg K2O/ha as sulphate of portals were used with 4 replications. These studies showed genotypic differences in germination, seedling growth and cell membrane stability. The germination experiment was repeated 3 times in petri plates. The Inqlab showed the highest germination stress index (86%) and lowest GSI was of Iqbal (68%). Present study also indicated that salinity significantly reduced the growth and yield components in different wheat varieties. However, K+ amendments reduce the effect of salinity to some extents because potassium application provided the osmotic adjustment to plants. The highest plant height was recorded in Inqlab and minimum in MH- 97; while the yield and yield parameters were higher in MH-97. The transpiration reduced and diffusive resistance increased under saline conditions. MH-97 maintained higher transpiration and low diffusive resistance which showed that this variety performed better in gas exchanging mechanism. Variety MH-97 higher yield and higher transpiration rate and low diffusive resistance. The amendments of K+ increased the transpiration under saline conditions reduced under normal conditions. The reduction in chlorophyll (A and total chlorophyll) due to salinity was also observed. The chlorophyll a/b ratio varied between 1.278 to 0.738 in control and saline plants while it was 1.278, 1.015 and 1.033 in control + K+ and salinity + K+ treated plants indicating that a/b ratio decreased under saline conditions and application of K+ increased it. Variety MH-97 maintained its chlorophyll content both under normal acid saline chlorophyll contents under normal as well as saline conditions in all wheat: varieties. MH- 97 also maintained the activity of nitrate reductase. Similarly K+ enhanced the nitrate reductase activity. Na+ increased while Ca2+, K+, P, N and SO4 decreased due to salinity but application of K+ enhanced their uptake except Na+. The present study confirmed that application of K increased the membrane stability and Ca2+ uptake. The application of K+ also enhanced the uptake of Nitrogen, Phosphorus and Sulphate. It can be concluded that salinity reduced the cell membrane stability, plant growth and imbalanced the nutrients metabolism in all wheat varieties, however, variety MH-97 performed better K+ increases the ability of plants to tolerate the environmental stress. Plants well supplied with K+ have better chance to overcome the stress conditions and produce a higher yield.
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