Effect of Low Temperature, Short Days, Water Stress and Dimethyl Sulphoxide on Frost Tolerance of Brassica juncea, Coss and Czern Var. Prakash

Treatment with low temperature, water stress or dimethyl sulphoxideinduces freeze tolerance in Brassica juncea, Coss and Czern.Short day-light periods for 3 or 6 d have no such effect. Percent ion efflux from leaves appears to be related to freezetolerance as determined by cell or plant survival tests. Increasedactivities of peroxidase and malate dehydrogenase are associatedwith freezing injury. Brassica juncea, freezing, water stress     

Effects of Sulphur Dioxide on Sugar and Free Amino Acid Content of Pine Seedlings

Treatment of jack pine (Pinus banksiana Lamb.) seedlings with gaseous SO₂ resulted in a shift between the reducing and non-reducing sugars. Increasing concentrations of gaseous SO₂ caused an increase in reducing sugars and a decline in the non-reducing sugars, suggesting a conversion from the latter to the former at high SO₂ concentrations. The total amino acid content of the intact tissues also increased with increasing concentrations of gaseous SO₂. Gas-liquid chromatographic analyses of the amino acids indicated that SO₂ (1. 34 mg · m^-3 for 96 h) resulted in an increase in the content of alanine, valine, glycine, isoleucine, leucine, threonine, aspartic acid tyrosine, lysine, and arginine, and a decrease in the content of serine and glutamic acid. The enzymatic and other implications of such changes are discussed.     

Variation in temperature and dietary nitrogen affect performance of the gypsy moth (Lymantria dispar L.)

Abstract. . The independent and interactive effects of temperature and dietary nitrogen content on performance of the gypsy moth (Lymantria dispar L.) were examined. In long-term feeding trials, larvae were reared from egg hatch to pupation on low (1.5%) and high (3.7% dry weight) nitrogen diets, under three temperature regimes. Short-term feeding trials with fourth instars and the same treatments were conducted in order to calculate nutritional indices.
Higher temperatures did not influence larval survival and marginally increased final pupal weights, but strongly decreased long-term development rates. They also accelerated short-term growth and consumption rates, and tended to improve food processing efficiencies. High concentrations of dietary nitrogen increased survival rates and final pupal weights markedly, but decreased long-term development rates only marginally. A high content of dietary nitrogen also accelerated short-term development and growth rates, reduced consumption rates, and improved food digestibility. Insects responded to low nitrogen-content diets primarily by eating faster, rather than by altering efficiency of nitrogen use. In the short-term feeding trials, thermal regime and dietary nitrogen interacted to influence growth rates, overall food processing efficiencies and nitrogen consumption rates. No interactive effects were observed in long-term studies.
This research demonstrates that small changes in thermal regime and ecologically relevant variation in dietary nitrogen content can strongly affect gypsy moth performance. Moreover, various performance parameters are differentially sensitive to the direct and interactive effects of temperature and diet.