Biomass and nutrient uptake ofAilanthus excelsa as affected by N and P fertilization on an aridisol

A field experiment was conducted on a coarse sand soil having pH 8.8 and organic matter 0.06% in Indian arid region, to study the influence of N and P fertilizers on growth, biomass and nutrient content ofAilanthus excelsa, which is an important fodder species of arid and semi arid regions. Three levels of nitrogen (0, 9 and 18 g N tree^–1 as Urea) and of phosphorus (0, 3 and 6 g P₂O₅ tree^–1 as Single Superphosphate) in factorial combinations were taken in triplicate and the experiment was laid in Randomised Block Design. Application of 9 g N plant^–1 improved tree height by 15 to 25%, collar circumference by 30 to 37% and crown diameter by 18 to 26% in the initial 3 years. Total biomass increase due to 9 g N plant^–1 was 76% and 59%, respectively, after 1 and 2 years of planting. Application of 3 g P₂O₅ tree^–1 increased tree height by 8 to 18% and collar circumference by 17 to 24% during initial three years, and total biomass by 70% at 1 year and 30% at 2 years of age. Combined application of 18 g N and 3 g P₂O₅ tree^–1 (N₁₈P₃) was the best treatment which increased tree height by 49%, 85% and 35% and collar circumference by 56%, 10% and 11% at 1, 2, and 3 years of age, respectively. N₁₈P₃ treatment increased the total biomass by 181% at 1 year and 185% at 2 years of age. N and P applications improved considerably the branching of roots and root length and enhanced root biomass by 2 to 3 folds. N₁₈P₃ treatment increased the nitrogen uptake by 304% (4.02 g tree^–1) at 1 year and 211% (42.56 g tree^–1) at 2 years of age. The P uptake was maximum (290.4 mg tree^–1) due to N₁₈P₃ treatment in 1 year old and 11.37 g tree^–1 due to N₉P₆ treatment in 2 year old plantation.     

Chemical and nutritional studies on hanshi (perilla frutescens), a traditional oilseed from northeast india

Perilla frutescens, an edible oilseed of Northeast India, was evaluated for its nutrient composition and protein quality. It was found to be a rich source of protein (17.0%) and fat (51.7%). The fatty acid profile indicated that perilla oil is rich in polyunsaturated fatty acids, such as linolenic (56.8%) and linoleic (17.6%). The amino acid composition showed that valine was the limiting amino acid of perilla protein. The protein efficiency ratio of the seed protein (2.07) was lower than that of casein (2.99), but comparable to common oilseeds. True digestibility of the seed protein (82.6%) was also lower than that of casein (89.3%).     

Influence of Seasonal Nitrogen Nutrition Fluctuations in Orange and Lemon Trees on Population Dynamics of the Glassy-Winged Sharpshooter (<Emphasis Type="Italic">Homalodisca coagulata</Emphasis>)

The glassy-winged sharpshooter (GWSS) is a xylem feeder that develops conspicuous, year-round populations in many citrus-producing regions of California. Field studies were conducted in a combined lemon and orange orchard to determine the influence of changing amino acid concentrations on relative densities of GWSS. Nineteen protein amino acids were detected in xylem fluid of both lemon and orange trees. Although annual profiles of total and essential amino acids were similar for each citrus species, mean concentrations were consistently higher in lemons than in oranges for most of the year, except for one critical period in late winter–early spring when concentrations were higher in oranges. Principal component analysis followed by factor analysis was performed individually on lemon and orange data sets to identify a reduced number of orthogonal factors composed of amino acids having similar seasonal profiles. Four factors were identified for each citrus species that accounted for 85% and 79% of the total variation in the orange and lemon analyses, respectively. These were then examined with respect to shifts in GWSS numbers that occurred asynchronously in lemons and oranges over the annual population cycle. Three distinctive number shifts were identified that included a peak in adult numbers in lemons during August 2001, significantly higher numbers in lemons relative to oranges during midwinter, and finally an increase in oranges of both adults and nymphs during spring 2002. Various groups of amino acids, i.e., factors, displayed peak annual or elevated levels during the intervals when shifts in GWSS numbers were occurring. Soluble protein levels in oranges and lemons did not correspond to shifting GWSS numbers as certain amino acids. However, soluble protein levels were higher in oranges during late winter/early spring when GWSS adults were sexually active. Potential roles of these amino acids and proteins in GWSS host selection are discussed.