Influence of sulphur fertilization on suppression of molybdenum uptake by berseem (Trifolium alexandrinum L.) and oats (Avena sativa L.) grown on a molybdenumtoxic soil

Summary Berseem (Trifolium alexandrinum L.) and oats (Avena satina L.) were grown in a greenhouse on a soil with a toxic level of available molybdenum. Significant increase in yield of berseem was observed on application of phosphorus and sulphur. The oat crop responded only to P application. The content of Mo in plants was enhanced by application of phosphorus. The application of sulphur depressed the Mo content of plants. The effect of P application was more conspicuous than the depressing effect of S application on Mo content of plants. The decrease in Mo content with S application was more pronounced in the oat crop. An application of 100 ppm S as gypsum caused 57.6 per cent decrease in the concentration of Mo which was below the threshhold toxic level. But in berseem, an application of 100 ppm S even could not lower the Mo concentration to a safer level. Gypsum and superphosphate were equally effective in lowering the concentration of Mo in berseem.Published as no 2 in the series: Molybdenum accumulation in forage crops, by the same authors.College of Agriculture and Radiation Soil Chemist, respectively.     

Growth and metabolic responses of contrasting chickpea (<Emphasis Type="Italic">Cicer arietinum</Emphasis> L.) genotypes to chilling stress at reproductive phase

Chilling stress (<10°C) at reproductive phase of chickpea results in abortion of flowers and pods leading to poor yield. The metabolic causes associated with cold sensitivity of chickpea are not well understood. Hence, in the present study, we evaluated four chickpea genotypes (ICC 16348, ICC 16349, PBG1 and GPF2) having contrasting cold sensitivity for their reproductive growth and metabolism subjected to cold stress (average day temperature: 17.6°C; average night temperature: 4.9°C). Genotypes ICC 16348 and ICC 16349 showed flowering and set pods, while PBG1 and GPF2 failed to do so during the stress conditions indicating the former to be cold tolerant. The stress injury in the leaves such as increase in electrolyte leakage, decrease in chlorophyll content and relative leaf water content was significantly less in ICC 16348 and ICC 16349 genotypes. The analysis of carbohydrates indicated total sugars and starch to be present in greater content in ICC 16348 and ICC 16349 relative to PBG1 and GPF2 genotypes. The enzymes related to carbohydrate metabolism such as β-amylase, invertase and sucrose synthase showed significantly higher activity in the leaves of ICC 16348 and ICC 16349 compared to the other two genotypes. PBG1 and GPF2 genotypes experienced greater oxidative stress measured as malondialdehyde and hydrogen peroxide. ICCV 16348 and ICC 16349 possessed significantly higher levels of enzymatic (superoxide dismutase, catalase, ascorbate peroxidase) and non-enzymatic antioxidants (proline and ascorbic acid) relative to PBG1 and GPF2. Particularly, proline and ascorbic acid were markedly higher in cold-tolerant genotypes compared to the sensitive ones suggesting their deciding role in governing the cold tolerance.