Muhammad Naeem

Seed priming with KNO3 mediates biochemical processes to inhibit lead (Pb) toxicity in maize (Zea mays L.)

BACKGROUNDnAccumulation of lead (Pb) in agricultural soils has become a major factor for reduced crop yields and poses serious threats to humans consuming agricultural products. The present study investigated the effects of KNO3 seed priming (0 and 0.5% KNO3 ) on growth of maize (Zea mays L.) seedlings exposed to Pb toxicity (0, 1300 and 2550 mg kg-1 Pb).nnnRESULTSnPb exposure markedly reduced the growth of maize seedlings and resulted in higher Pb accumulation in roots than shoots. Pretreatment of seeds with KNO3 significantly improved the germination percentage and increased physiological indices. A stimulating effect of KNO3 seed priming was also observed on pigments (chlorophyll a, b, total chlorophyll and carotenoid contents) of Pb-stressed plants. Low translocation of Pb from roots to shoots caused an increased accumulation of total free amino acids and higher activities of catalase, peroxidase, superoxide dismutase and ascorbate peroxidase in roots as compared to shoot, which were further enhanced by exogenous KNO3 supply to prevent Pb toxicity.nnnCONCLUSIONnMaize accumulates more Pb in roots than shoot at early growth stages. Priming of seeds with KNO3 prevents Pb toxicity, which may be exploited to improve seedling establishment in crop species grown under Pb contaminated soils.

Improving the performance of bread wheat genotypes by managing irrigation and nitrogen under semi-arid conditions

ABSTRACT Wheat (Triticum aestivum L.) productivity is generally affected by water limitation and inadequate nitrogen supply especially under semi-arid environment. The current study was conducted to determine whether the crop yield and irrigation water use efficiency (IWUE) could be manipulated through alteration of nitrogen and irrigation application. To meet the desired objectives, a two-year field study was carried out in 2013–2014 and 2014–2015, in a split-split plot arrangement with three factors i) irrigation in main plots, ii) nitrogen in sub-plots, and iii) twenty genotypes in sub-sub plots on a sandy loam soil. The analysis of variance revealed that the wheat performance was affected by genotypes and alteration of irrigation and nitrogen application with respect to IWUE and final grain yield. IWUE under water stress conditions was observed 56% higher than normal irrigated. Much higher values of IWUE under water stress indicated that the existing optimum water requirements of the crop needs to be revaluated. The regression model indicated that addition of nitrogen and irrigation patterns along with morphological traits cannot explain variation in yield related traits more than 65% under semi-arid conditions. Therefore, for better crop yields in semi-arid environment, more physiological parameters should be considered in evaluation of yield.

Physiological Responses of Wheat ( Triticum aestivum L.) to Drought Stress

Drought is serious problem in many parts of the world in circumstances of rapid change in climatic conditions especially for rainfed agriculture. Among prevailing abiotic stresses, it is the most significant and severe factor inhibiting plant growth and pr oduction. Water deficiency in plant impairs the numerous physiological and metabolic functions. Selection of wheat genotypes that can tolerate water scarcity would be helpful tools for breeding program aiming to development of drought tolerant variety unde r water limited regions. Rapid development of new wheat varieties with the help of analytical breeding would be the most attractive approach. In this review paper, after the brief introduction about the present scenario of food insecurity, the impact of dr ought and about the targeted approaches for drought stress, we briefly review the already work done to deal with this environmental calamity (drought). We discussed in detail the important physiological traits (viz. proline content, relative water content, chlorophyll content, cell membrane stability and canopy temperature) having important role in wheat to estimate the drought tolerance and to improve the