Farrukh Javed

Nitrate Reduction and Nutrient Accumulation in Wheat Grown in Soil Salinized with Four Different Salts

ABSTRACT The effect of salinization of soil with Na2SO4, CaCl2, MgCl2, and NaCl (70:35:10:23) on the biochemical characteristics of three wheat (Triticum aestivum L.) cultivars (‘LU-26S,’ ‘Sarsabaz’ and ‘Pasban-90’) was investigated under natural environmental conditions. Twenty-day-old seedlings of all three cultivars were subjected to three salinity treatments: 1.3 (control), 5.0, and 10 dSm−1 for the entire life period of plants. After 120 d of seed sowing, plant biomass production decreased by 49% and 65%, respectively, in response to 5 and 10 dSm−1 salinity levels. Addition of salts to growth medium also had a significant adverse effect on plant height. Increasing salinity treatments caused a great reduction in nitrate reductase activity (NRA) of the leaf. The inhibitory effect of salinity on nitrate reduction rate was more pronounced at the reproductive stage than at the vegetative stage of plant growth. Wheat cultivars ‘LU-26S’ and ‘Sarsabaz’ showed less reduction in NRA due to salinity compared with ‘Pasban-90.’ Ascending salinity levels significantly reduced potassium (K+) and calcium (Ca2+) accumulation in shoots, while the concentration of sodium (Na+) was increased. Salts of growth medium increased the shoot nitrogen (N) concentration, whereas phosphorous (P) concentration of shoots was significantly reduced due to salinity. Wheat cultivars ‘LU-26S’ and ‘Sarsabaz’ proved to be the salt-tolerant ones, producing greater biomass, showing less reduction in NRA, maintaining low sodium (Na+), and accumulating more K+ and Ca2+ in response to salinity. These two cultivars also showed less reduction in shoot K+/Na+ and Ca+/Na+ ratios than in ‘Pasban-90,’ particularly at the 10 dSm−1 salinity level.

Relationship between Callus Growth and Mineral Nutrients Uptake in Salt-Stressed Indica Rice Callus

ABSTRACT One month old rice calli were exposed to 0, 50, and 100 mol m−3 sodium chloride (NaCl) in the liquid LS basal medium supplemented with 2.5 mg L−1 2,4-dichlorophenoxy acetic acid (2,4-D) and 0.5 mg L−1 kinetin. Callus relative growth rate (RGR; fresh) of both cultivars indicated a progressive decrease; however, callus dry weight increased as the NaCl level increased in the culture medium. Salinity stress increased the callus sodium (Na+), manganese (Mn2+), and magnesium (Mg2+) contents while potassium (K+), calcium (Ca2+), and iron (Fe2+) contents decreased. ‘Basmati-385’ showed less reduction in callus RGR, K+, and Ca2+ contents and a larger increase in callus dry weight, Na+, Mn2+, and Mg2+ contents as compared to ‘Basmati-Karnal’. However, the reverse was true for Fe2+ contents. K+/Na+ and Ca2+/Na+ ratios generally decreased under salt stress. Overall, reduction in callus relative growth rate was found to be inversely correlated with decrease in K+, Ca2+, and Fe2+ uptake and directly correlated with increased Na+ and Mg2+ concentration in callus tissue.

Alleviating effect of exogenous application of ascorbic acid on growth and mineral nutrients in cadmium stressed barley (Hordeum vulgare) seedlings.

An experiment was carried out in sand-filled pots under normal temperature (28±2oC) to assess the role of exogenously applied ascorbic acid in alleviating the effect of cadmium (Cd) stress on four barley (Hordeum vulgare L.) genotypes (Jau-83, Jau-87, Paidar 91 and Haider 93). After germination, seedlings were exposed to different Cd concentrations (0, 100, 300, 500 and 700 μM CdCl2) along with AsA (200 mg L) and grown for 15 days. The results suggested that exposure to increased Cd levels caused a significant reduction in growth and mineral nutrients contents of barley seedlings. However, there was a noticeable difference in the effect of Cd on mineral concentrations among genotypes and the difference mainly coincided with differential accumulation of Cd in the shoot and root tissues. When AsA was applied to Cd-stressed plants, it decreased Cd accumulation in shoots and roots and also showed partial reversal of Cd stress effects. It was also observed that at the same Cd concentrations Cd tolerance index of Jau-83 was the highest among the four barley genotypes, indicating that Jau-83 had lower Cd contents in roots may be more tolerant to Cd stress. The application of AsA was effective in reducing the toxicity of increased Cd by reducing the root or shoots Cd contents, as well as by improving the seedling growth attributes and the mineral nutrients in barley.

In vitro Study of Interactive Effect of Cadmium and Salicylic Acid on Growth and Biochemical Parameters in Tetra and Hexaploid Wheat

In vitro cultures of plants offer a useful tool to study the adaptive mechanisms of plants in the presence of high metal concentrations. Callus cultures of tetraploid (Durum-97) and hexaploid (Shafaq-06) wheat genotypes exposed to different cadmium (Cd) concentrations (0, 100, 400, 800 and 1200 μM) and its alleviation by salicylic acid (0, 0.5 mM) were assayed for growth, antioxidant responses and Cd accumulation characters. Cadmium hampered the growth and notably enhanced antioxidant activity in all Cd regimes. We provided evidence that the two genotypes hexaploid and tetraploid are characterized by different response to cellular homeostasis and detoxification to Cd in callus culture. In particular, the high tolerance in hexploid genotype (Shafaq-06) is associated with relatively higher activity of antioxidants and Cd accumulation behaviour as indicated by Cd contents, bioconcentration factor (BCF) and stress tolerance index (STI). However, the follow-up treatment (0.5 mM) with salicylic acid (SA) mitigated the Cd generated stress and significantly (P≤0.05) improved the aforesaid parameters.