Volatile losses of sulfur from intact plants

Losses of volatile sulfur (S) compounds were measured from intact plants of 22 species including tropical and temperate crop and pasture species grown under glasshouse conditions. All species released substantial amounts of S during a 22‐hour collection period. The amounts lost ranged from 0.13 μg S g dry weight of shoot^‐1 22 hours^‐1 in barrel medic to 2.68 μg S g dry weight of shoot^‐1 22 hours^‐1 in rape. These losses represented 0.005% of the total S in the shoot in barrel medic and 0.92% in rape. There was no obvious division between temperate and tropical species in terms of the amounts of volatile sulfur compounds released, but the evidence suggested that tropical species released a different spectrum of volatile sulfur compounds from temperate species. Thus in tropical grasses and legumes, a higher proportion of the total volatiles was recovered in cold traps, whereas in temperate grasses and legumes, a higher proportion of the total volatiles was recovered in activated carbon traps located after the cold traps. When all 22 species were considered together, the amount of volatile S lost was not correlated with the S concentration in the shoot. Extrapolation of these short term observations in the glasshouse to longer term losses under field conditions suggests that losses of volatile S from fields of alfalfa, Rhodes grass, and wheat may be in the order of hundreds of grams of S ha^‐1 year^‐1, while losses from fields of cotton may be in the order of thousands of grams of S ha^‐1 year^‐1.     

Volatile losses of sulphur from oven drying lucerne (Medicago sativa L.): Effects of sulphur,nitrogen, phosphorus and potassium supply

Lucerne was grown in nutrient solutions at adequate and “deficient”; levels of sulphur, nitrogen, phosphorus or potassium. Volatile losses of sulphur were then measured when shoots and roots were oven dried at 80°C for 48 hours.

Small but significant losses of sulphur occurred during oven drying. Losses from shoots ranged from 4.2 to 13.9 μgS/g dry weight, which represented from 0.38 to 0.66% of the total sulphur content of the shoot. Losses from roots ranged from 12.0 to 47.8 μgS/g dry weight, representing 0.82 to 1.77% of the total sulphur content of the root. Decreases in supply of nitrogen, phosphorus, potassium or sulphur generally decreased the amount of volatile sulphur lost by oven drying shoots. Losses from roots generally decreased when supply of sulphur decreased, but increased when nitrogen and potassium supply decreased, and were generally unaffected by phosphorus supply.

The organic sulphur concentration in the tissue was linearly correlated with absolute losses of sulphur (r = 0.799** for shoots; r = 0.822** for roots), the amount of sulphur lost per unit dry weight (r = 0.469* for shoots; r = 0.381* for roots) and the percentage of the total sulphur released as volatile sulphur (r = 0.937** for shoots; r = 0.970** for roots). By contrast, the total sulphur concentration in the tissue was linearly correlated only with the amount of sulphur lost per unit dry weight ( r = 0.704** for shoots; r = 0.723** for roots).     

A rapid and easy method of detecting levels of gene expression in intact tobacco plants using an Agrobacterium-mediated transient assay: Toward development of nutritional diagnosis based on gene expression

For the use of gene expression for nutritional diagnosis, a rapid and easy method of detecting levels of gene expression was proposed. Agrobacterium tumefaciens carrying the GUS reporter gene was injected into intact tobacco leaves with a plastic syringe, and transient GUS expression was determined. GUS activities were reproducible in young leaves.     

Alleviation of salinity stress in red cabbage plants by urea and sulfur applications

Environmental stresses, such as salinity, are becoming critical constraints to plant production especially in arid and semi-arid regions, one of the main targets of agricultural studies is to combat the environmental stresses on plants. An open field experiment was carried out to study the influence of sulfur (S) and urea on red cabbage plants under salt stress. The experiment was arranged as a split-plot design with three replications, the main plots included sulfur levels (0, 350, and 700 kg ha^?1), while subplots included urea levels (0, 1, 2, and 4 g L^?1). Results showed that urea spraying and sulfur soil additions resulted in improvement of growth and yield, and raised the level of potassium and nitrogen while lowering sodium content in plant leaves under salt stress conditions. Generally, larger and heavier heads were found with the application of 700 kg ha^?1 sulfur and 2 g L^?1 urea.