Regulation of Leaf Senescence and Yield in Mungbean (Vigna radiata L. Wilczek)

Foliar application of benzyladenine at preanthesis stage retarded leaf senescence in mungbean. Chemical spray increased leaf chlorophyll, soluble protein, specific leaf weight, net photosynthetic rate and nitrate reductase activity. Number of pods, grain yield, harvest index and 100-seed weight were significantly improved by benzyladenine treatment. The possibility of higher pod-filling and thus, yield by chemical regulation of leaf senescence is evident in mungbean.     

Antifungal activity of flavonoids and their mixtures against different fungi occurring on grain

The antifungal activity of three flavones and one flavanone and of different mixtures of these flavonoids was investigated on malt extract agar against four fungi usually occurring on grain. As pure substances the unsubstituted flavone and flavanone showed higher activity than the hydroxylated flavones. Mixtures containing flavone and 7-hydroxyflavon or flavone, flavanone and flavonol caused higher inhibition of fungal growth than the remaining ones.     

Development of DRAIN-WARMF model to simulate flow and nitrogen transport in a tile-drained agricultural watershed in Eastern Canada

A new watershed model, DRAIN-WARMF, was developed to simulate the hydrologic processes and the nitrogen fate and transport that occur in small, predominantly subsurface-drained, agricultural watersheds that experience periodic freezing and thawing conditions. In this modeling approach, surface flow is simulated using a watershed scale model, WARMF, and subsurface flow is estimated using a field-scale model for subsurface-drained shallow water table fields, DRAINMOD 5.1. For subsurface flow calculations, the watershed is subdivided into uniform cells, and DRAINMOD is run on each cell with inputs based on the individual hydrologic characteristics of the cell. The coupling results in a distributed parameter model that calculates the total flow at the outlet of a watershed as well as the nitrogen losses. The model was evaluated for the St. Esprit watershed, located approximately 50 km northeast of Montreal. Simulations were carried out from 1994 to 1996; data from 1994 and 1995 was used for model calibration and data from 1996 was used for model validation. The new model was able to adequately simulate the hydrologic response and nitrate losses at the outlet of the watershed. Comparing the observed daily flow/monthly nitrogen with the model's outputs over the validation period returned an R² value of 0.74/0.86 and modeling efficiency of 0.72/0.83. This clearly demonstrates the model's ability to simulate hydrology and nitrogen losses occurring in small agricultural watersheds in cold climates.     

干旱热带地区土地利用变化对土壤微生物群落组成及有机碳含量的影响

Restoration of forests poses a major challenge globally,particularly in the tropics,as the forests in these regions are more vulnerable to land-use change.We studied land-use change from natural forest (NF) to degraded forest (DF),and subsequently to either Jatropha curcas plantation (JP) or agroecosystem (AG),in the dry tropics of Uttar Pradesh,India,with respect to its impacts on soil microbial community composition as indicated by phospholipid fatty acid (PLFA) biomarkers and soil organic carbon (SOC) content.The trend of bacterial PLFAs across all land-use types was in the order:NF ＞ JP ＞ DF＞ AG.In NF,there was dominance of gram-negative bacterial (G-) PLFAs over the corresponding gram-positive bacterial (G+) PLFAs.The levels of G-PLFAs in AG and JP differed significantly from those in DF,whereas those of G+ PLFAs were relatively similar in these three land-use types.Fungal PLFAs,however,followed a different trend:NF ＞ JP ＞ DF =AG.Total PLFAs,fungal/bacterial (F/B) PLFA ratio,and SOC content followed trends similar to that of bacterial PLFAs.Across all land-use types,there were strong positive relationships between SOC content and G-,bacterial,fungal,and total microbial PLFAs and F/B PLFA ratio.Compared with bacterial PLFAs,fungal PLFAs appeared to be more responsive to land-use change.The F/B PLFA ratio,fungal PLFAs,and bacterial PLFAs explained 91％,94％,and 73％ of the variability in SOC content,respectively.The higher F/B PLFA ratio in JP favored more soil C storage,leading to faster ecosystem recovery compared to either AG or DF.The F/B PLFA ratio could be used as an early indicator of ecosystem recovery in response to disturbance,particularly in relation to land-use change.     

Prevalence and molecular characterization of bovine Cryptosporidium isolates in India

A survey based on PCR assay of 18S SSU rRNA gene revealed a 30.2% infection with Cryptosporidium spp., out of 457 faecal samples collected from neonatal bovine calves across three different regions of India. The PCR-RFLP pattern of the gene in all the positive cases established the species as Cryptosporidium parvum. Highest prevalence was recorded in the monsoon months (37.3%) and in the calves showing acute diarrhoea (32.3%). The calves below 15 days of age were mostly affected (45.1%). The infection was more prevalent in the northern parts (35.4%) of the country than in the eastern or southern parts. Results indicated that C. parvum was the only species of Cryptosporidium prevalent in bovine calves in three different geographical regions of India.     

Uptake of multielements by corn from fly ash-compost amended soil

Fly ash was collected from a coal-fired power plant in and near the U.S. Department of Energy Savannah River Site to study the feasibility of the application of fly ash compost mixture to soils for the availability and uptake of various elements by corn (Zea mays L.). The crop was grown in potted Ogeechee sandy loam soil using eight treatments: soil alone, soil amended with 15% compost, and soil amended with 2, 5, 10, 15, 20 and 25% of fly ash-amended compost. It was observed that 20–25% fly ash and compost soil ratio treatments generally increased plant growth and the yield. The plant uptake of K, Mn, and Cu increased with increasing percentages (2–25%) of fly ash+compost: soil ratios. The total content of K in plants was positively correlated with the dry matter yield of corn. This study indicates that the application of fly ash blended with compost to soil is beneficial to corn production without causing any deleterious effects on plant growth and plant composition.     

Variation in transpiration efficiency and its related traits in a groundnut (Arachis hypogaea L.) mapping population

Transpiration efficiency (TE) has been recognized as an important source of yield variation under drought stress in groundnut. Here the variation for TE is evaluated in a set of 318 recombinant inbred lines (RILs) of groundnut at F₈ generation, derived from a cross between a high TE (ICGV 86031) and a low TE (TAG 24) parent, and the value of specific leaf area (SLA), SPAD chlorophyll meter readings (SCMR) and carbon isotope discrimination (Δ¹³C) as surrogates of TE are measured. Transpiration efficiency was measured gravimetrically in the 318 RILs and parents under progressive soil drying in a pot culture in two post-rainy seasons. Large and consistent variation for TE existed among the RILs across years. The overall distribution of TE among the RILs indicated that TE was governed by dominant and additive genes. Surrogates SLA and SCMR, were measured prior, during and after completion of the drought period, whereas Δ¹³C was measured on the dried tissue after harvest. Transpiration efficiency was negatively associated with SLA after the completion of stress treatment (r² = 0.15) and Δ¹³C in leaves (r² = 0.13) and positively associated with SCMR during stress (r² = 0.17). These associations, all fairly weak, were significant only in 2004. None of these relationships was found in 2005. Although the heritability of SCMR during 2005 was relatively higher than that of TE, and although SCMR has previously been used to identify contrasting germplasm for TE, the stress-dependence of the relationship with TE, and the poor regression coefficients (r²) with that RIL population, do not confer that these surrogates are adequately robust enough in that population. Though more time consuming, a direct gravimetric evaluation for TE appeared to be more reliable.     

New report of Hirsutella sp. infecting mango hopper Idioscopus clypealis from Chotanagpur Plateau, India

An entomopathogenic fungus belonging to the genus Hirsutella was found infecting the mango hopper, Idioscopus clypealis (Lethierry) (Hemiptera: Cicadellidae), for the first time in India in September 2011. The report of a natural control agent of mango hopper during the off season has special significance because its outbreak depends upon its residual hibernating population.     

Effect of Water Stress on Biochemical and Physiological Characteristics of Oat Genotypes

Activities of enzymes catalase, peroxidase, and level of total soluble proteins were studied in two genotypes (JHO 884, JHO 888) of oat ( Avena sativa L.) subjected to water stress for 1, 3, and 4 days by withholding water in a pot culture experiment. No change was observed in the level of total soluble proteins at early stage but it increased significantly at higher magnitude of water stress. Increase in catalase activity was noticed in JHO 884 whereas reverse trend was observed in JHO 888 at highest level of stress. The JHO 884 genotype showed increase in peroxidase activity from the first day of water stress. Results suggest that the efficiency level of antioxidant system is found different in these two genotypes.