Effect of Salts Stress on the Growth and Yield of Wheat (Triticum aestivum L.)

In order to study the effect of salts stress on the growth and yield of wheat (cv. Inqalab), a pot experiment was conducted in the wire-house of the Department of Soil Science, Sindh Agriculture University Tando Jam. The soil was artificially salinized to a range of salinity levels i.e . EC 2.16, 4.0, 6.0, 8.0 and 10.0 dS·m-1 with different salts (MgCl2 + CaCl2 + Na2SO4). The salinized soil used for the experiment was sandy clay in texture, alkaline in reaction (pH > 7.0) and moderate in organic matter (0.95%) content. The results showed that with increasing salinity there was an increase in the ECe, Na+, Ca2+, Mg2+ and Cl- and decrease in the K+, SAR and ESP values of the soil Increasing salinity, progressively decreased plant height, spike length, number of spikelets spike-1 1000 grain weight and yield (straw and grain). Adverse effects of salts on plants were associated with the accumulation of less K+ and more Na+ and Cl- in their flag leaf sap, grains and straw. This resulted in lower K+:5Na+ ratio in flag leaf sap, grains and straw of wheat plants. These results indicated that the effects of salts stress were greater at 10 than at 8, 6 and 4 EC dS·m-1.

Effect of Different Levels of Phosphorus and Method of Application on the Growth and Yield of Wheat

An experiment was conducted to evaluate the productivity of wheat under different levels of phosphorus and method of application at Department of Agronomy, Sindh Agriculture University, Tandojam. Experiment was laid out in a RCBD (factorial) with three replications. The treatments were four phosphorus levels (P1 = 0 Kg?ha–1 + Recommended Nitrogen, P2 = 30 Kg?ha–1 + Recommended Nitrogen, P3 = 60 Kg?ha–1 + Recommended Nitrogen and P4 = 90 Kg?ha–1 + Recommended Nitrogen) and two placement methods (A1 = Drilling method and A2 = Broadcast method). The statistical analysis of phosphorus levels and placement exhibited significant differences to the maturity days, plant height, tiller production, spike length, grains per spike, seed index, harvest index and grain yield ha–1. However, the interactions of P levels and placement in all crop characters were non-significant except the grain yield/ha–1. The results revealed that application of 90 kg P ha–1 prolonged 143 days for maturity, taller plants (100.16 cm), more tiller plant–1 (13.50), lengthy spikes (12.83 cm), more grains spike–1 (51.33), heavier seed index (48.16 g), better harvest index (50.82%) and satisfactory grain yield (4240.50 Kg?ha–1). The unit increase in grain yield was positively correlated with the increased values of observed crop parameters by extending the values of maturity r = 0.85, plant height r = 0.94, tillers plant r = 0.96, spike length r = 0.95, grains spik–1 r = 0.97, seed index r = 0.95 and harvest index r = 0.97. It was concluded that 90 kg P ha–1 was superior level of phosphorus if, applied with seed drilling for obtaining satisfactory grain yield of wheat crop.

Nitric oxide alleviates aluminum-induced oxidative damage through regulating the ascorbateglutathione cycle in roots of wheat

The possible association with nitric oxide （NO） and ascorbate-glutathione （AsA-GSH） cycle in regulating aluminum （Al） tolerance of wheat （Triticum aestivum L.） was investigated using two genotypes with different Al resistance. Exposure to Al inhibited root elongation, and triggered lipid peroxidation and oxidation of AsA to dehydroascorbate and GSH to glutathione disulfide in wheat roots. Exogenous NO significantly increased endogenous NO levels, and subsequently al eviated Al-induced inhibition of root elongation and oxidation of AsA and GSH to maintain the redox molecules in the reduced form in both wheat genotypes. Under Al stress, significantly increased activities and gene transcriptional levels of ascorbate peroxi-dase, glutathione reductase, and dehydroascorbate reductase, were observed in the root tips of the Al-tolerant genotype Jian-864. Nitric oxide application enhanced the activity and gene transcriptional level of these enzymes in both wheat geno-types. g-Glutamylcysteine synthetase was not significantly affected by Al or NO, but NO treatments increased the activity of glutathione peroxidase and glutathione S-transferase to a greater extent than the Al-treated wheat seedlings. Proline was significantly decreased by Al, while it was not affected by NO. These results clearly suggest that NO protects wheat root against Al-induced oxidative stress, possibly through its regulation of the AsA-GSH cycle.

A newly recorded genus of the Rhamphothrips genus-group (Thysanoptera: Thripidae) from China

The genus Parexothrips Priesner of Rhamphothrips genus-group（Thripidae： Thripinae） is recorded in China for the first time. A new record species, Parexothrips tenellus（Priesner）, is described and illustrated from China. A key to genera of Chinese Rhamphothrips genus-group is provided. Examined specimens are deposited in the Insect Collection of Department of Entomology, South China Agricultural University（SCAU）.