Effect of varying high temperatures during reproductive growth on reproductive function,oxidative stress and seed yield in chickpea genotypes differing in heat sensitivity

The mechanisms affecting the heat sensitivity of chickpea are largely unknown. Heat-tolerant (ICCV07110, ICCV92944) and heat-sensitive (ICC14183, ICC5912) chickpea genotypes were sown in February in the soil-filled pots. At the time of flowering, these were subjected to varying day/night temperatures of 30/20, 35/25, 40/30 and 45/35°C in the growth chambers (12 h light/12 h dark; light intensity, 250 μmol m^?2 s^?1, 80% relative humidity). The pollen viability, pollen germination, tube growth, pollen load and stigma receptivity decreased with increases in temperatures to 45/35°C. The heat-tolerant genotypes experienced significantly less damage to pollen and stigma function. Membrane integrity, chlorophyll content, photochemical efficiency and cellular oxidizing ability were inhibited by the increase in temperature, with greater impacts on the sensitive genotypes. Oxidative injury as lipid peroxidation and hydrogen peroxide content was significantly greater in sensitive genotypes at 40/30 and 45/35°C. Enzymatic and non-enzymatic antioxidants showed increased levels at 40/30°C, but decreased considerably at 45/35°C. Heat-tolerant genotypes possessed greater activity of ascorbate peroxidase and glutathione reductase, along with higher levels of ascorbate and reduced glutathione at 40/30 and 45/35°C. Biomass, pod set and yield were not affected significantly at 35/25°C, but began to decrease at 40/30°C and were lowest at 45/35°C. The sensitive genotypes were not able to set any pods at 45/35°C, whereas the tolerant genotypes produced only few fertile pods at this temperature. It was concluded that heat stress leads to loss of pollen as well as stigma function and induces oxidative stress in the leaves that cause failure of fertilization and damage to the leaves, respectively.     

Effect of feeding stimulants on the insecticidal properties of Pieris brassicae granulovirus (PbGV) against Pieris brassicae

Feeding stimulants (phagostimulants) increase the food uptake by the host insect larvae and thereby play a vital role in enhancing overall activity of insect viruses formulated as biopesticides. A local strain of granulovirus of Pieris brassicae (PbGV), a serious pest of cole crops worldwide, has shown potential as a biopesticide against this pest and with slight increase in its efficacy can be used successfully as a promising biocontrol agent in integrated pest management (IPM) programs of the pest. The addition of phagostimulants may enhance the efficacy but so far no specific phagostimulant for PbGV has been reported. In the present studies, some reported phagostimulants for insect viruses were tested for their impact on food utilization by host larvae and efficacy of the virus. The specified concentration of virus isolate was mixed with phagostimulants and laboratory studies were conducted to uncover their effect on consumption index (CI) and larval mortality. The studies revealed that phagostimulants, viz. boric acid and crude sugar, when mixed with PbGV, showed highest CI and larval mortality. Consumption index of 1.34, 1.49 and 1.43 mg/mg/day and corresponding larval mortality of 32.9%, 45.8% and 34.2% were recorded with the addition of 0.5% and 1% boric acid and 2% crude sugar, respectively, in PbGV. The leaf extracts of cabbage, cauliflower and broccoli at both the concentrations (1% and 2%) also enhanced the CI but were comparatively less effective than the boric acid and crude sugar. Field evaluation of PbGV alone and in combination with phagostimulants carried out at two geographically isolated locations, viz. Palampur (subtropical) and Sangla (temperate) on three cole crops (cabbage, cauliflower and broccoli) showed that boric acid was the most promising candidate for enhancing the PbGV efficacy under field conditions, followed by crude sugar.     

Nutritional evaluation of wheat straw treated with Crinipellis sp. in Sahiwal calves

Wheat straw was subjected to solid-state fermentation (SSF) with lignolytic white-rot fungus (WRF) Crinipellis sp. for 5 days to improve the nutritive value and digestibility. The fungal treatment caused a significant (P?<?0.05) decrease in cell wall constituents viz., neutral detergent fiber (NDF), acid detergent fiber (ADF), hemicellulose, lignin, and cellulose to the extent of 10.4, 11.2, 8.7, 8.7, and 12.1 %, respectively, with increase (P?<?0.05) in crude protein (CP) (51.6%) and ash (25.8%) contents in fungal treated wheat straw (FT-WS) than untreated wheat straw (UT-WS). Further, in vitro gas production, in vitro true dry matter digestibility and in vitro true organic matter digestibility at 48 h, metabolizable energy (ME) content, microbial biomass production, and short-chain fatty acids synthesis were significantly (P?<?0.05) higher in FT-WS. In vivo feeding trial in 10 Sahiwal calves (8–12 months) comprised of (1) control group (T1) fed with ad libitum chopped UT-WS and (2) treatment group (T2) offered with ad libitum chopped FT-WS, in addition to supplementation of groundnut cake and green berseem (Trifolium alexandrium) forage to both groups. Digestibility of nutrients for dry matter (DM), organic matter, CP, NDF, ADF, hemicellulose, cellulose, and total carbohydrates were significantly (P?<?0.05) higher in T2 compared to T1. Moreover, daily DM (P?<?0.05), digestible crude protein (P?<?0.01), and ME intakes were also higher (P?<?0.05) in group T2 with higher (P?<?0.05) nitrogen (N) retention, which resulted in significantly (P?<?0.05) higher average daily gain in body weight (135 vs. 102 g/day). It was concluded that SSF with WRF Crinipellis sp. holds potential in upgrading the nutritional worth of wheat straw for feeding growing calves.     

Analysis of Genetic Diversity Among Saccharum spontaneum L. From Four Geographical Regions of India, Using Molecular Markers

Saccharum spontaneum L. a wild relative of sugarcane is the most variable and diverse among the Saccharum species. This species had been successfully exploited in sugarcane improvement programmes since 1915 and most of the present day commercial varieties are derivatives of interspecific hybrids involving S. spontaneum. The S. spontaneum germplasm available today in the World collections is diverse and represent different geographical groups. In the present investigation, an attempt was made to characterize 40 S. spontaneum clones collected from 4 different geographical areas in India using 20 random, 2 ISSR and 2 telomere primers. Of the 491 bands generated by these primers 83.9% were polymorphic. The genetic diversity estimated based on these markers was found to be moderate (48.9%). The pair-wise genetic distance between the accessions ranged from 29.8 to 60.0. The accessions from Arunachal Pradesh were found to be the most diverse, while Tamil Nadu accessions showed relatively less diversity. Diversity between Tamil Nadu and Kerala collections was found to be low, while the diversity between the Orissa group and the rest was found to be high. The collections from Mayurbanj and Cuttack regions of Orissa were found to be distinct. Arunachal Pradesh accessions, being more diverse, are a potential source for exploitation in sugarcane breeding programmes.     

Diffuse reflectance spectroscopy (DRS) for rapid soil testing and soil quality assessment in smallholder farms

Rapid soil testing and soil quality assessment are essential to address soil degradation and low farm incomes in smallholder farms. With the objective of testing diffuse reflectance spectroscopy (DRS) to rapidly assess soil chemical properties, nutrient content and a soil quality index (SQI), samples of surface soil were collected from 1113 smallholder farms in seven districts in Bundelkhand region of Uttar Pradesh, India. A minimum dataset (MDS) approach was followed to estimate SQI using the three chemical parameters of soil pH, electrical conductivity (EC) and soil organic carbon (SOC), and 11 different soil nutrients. Principal component and correlation analyses showed that soil pH, SOC content and three available nutrients − copper (Cu), iron (Fe) and sulphur (S) − may constitute the MDS. Estimated SQI values showed strong positive correlation with crop yields. Results of chemometric modelling showed that the DRS approach could yield the coefficient of determination (R²) values in the validation datasets ranging from 0.79 to 0.94 for exchangeable calcium (Ca) followed by 0.67–0.88 for exchangeable potassium (K), 0.52–0.86 for SOC and 0.53–0.81 for available boron (B) content. Except in one district, the DRS approach could be used to estimate SQI values with R² values in the range of 0.63–0.81; an R² value of 0.71 was obtained in the pooled dataset. We also estimated the three-tier soil test crop response (STCR) ratings to compare DRS and wet chemistry soil testing approaches. Similar STCR ratings were obtained for both these approaches in more than 86% of the samples. Parameters for which both the methods yielded similar ratings in more than 80% of the samples were EC (>98%), pH and exchangeable Ca (>81%) and available B (>89%). With similar ratings, these results suggest that the DRS approach may safely be used for farmers' fields, replacing the traditional wet analysis approach of soil testing.     

Enhanced soybean (Glycine max L.) plant growth and nodulation by Bradyrhizobium japonicum-SB1 in presence of Bacillus thuringiensis-KR1

Abstract

Nodulation and subsequent nitrogen fixation are important factors that determine the productivity of soybean (Glycine max L.). The beneficial effects of nodulation can be enhanced when rhizobial inoculation is combined with plant-growth-promoting bacteria (PGPB). The PGPB strain Bacillus thuringiensis-KR1, originally isolated from the nodules of Kudzu vine (Pueraria thunbergiana), was found to promote growth of soybean plants (variety VL Soya 2) under Jensen's tube and growth pouch conditions, when co-inoculated with Bradyrhizobium japonicum-SB1. Co-inoculation with Bacillus thuringiensis-KR1 (at a cell density of 10 cfu) provided the highest and most consistent increase in nodule number, shoot weight, root weight, root volume, and total biomass, over rhizobial inoculation and control, under both conditions. The results demonstrate the potential benefits of using nonrhizobial nodule occupants of wild legumes for the co-inoculation of soybean, with Bradyrhizobium japonicum-SB1, in order to achieve plant-growth promotion and increased nodulation.     

Effect of deep placement of calcium cyanamide,coated urea,and urea on soybean (Glycine max (L.) Merr.) seed yield in relation to different inoculation methods

Abstract

The main objective of this study was to increase the productivity of soybean [Glycine max (L.) Merr. cv. Enrei] seed by deep placement of controlled release nitrogen fertilizers and by the application of different methods of inoculation of bradyrhizobia. Ten days old seedlings in an inoculated paper pot (IPP), in a non-inoculated paper pot (NIPP), and those grown in a vermiculite bed without paper pot (DT) were transplanted to an upland field converted from a drained paddy field in Nagaoka. In addition to the basal application of 16 kg N ha^?1 in the surface layer (Control), deep placement of 100 kg N ha^?1 of urea (Urea), 100-day type coated urea (CU-100), and calcium cyanamide (CaCN₂) treatments were applied at the depth of 20 cm. In the IPP method, a significantly higher seed yield was obtained with the deep placement of CaCN₂ and CU-100 compared with the Urea and Control treatments. A similar tendency was observed for the DT and NIPP methods. Among the same N fertilizer treatments, the seed yield for IPP and DT tended to exceed that for NIPP, although the NIPP roots also showed nodulation probably due to infection with indigenous bradyrhizobia. The percentage of nitrogen derived from atmospheric N₂ estimated by the simple relative ureide method was higher in the plants with CU-100 and CaCN₂ compared with those with the Urea and Control treatments at the RI stage, suggesting that the basal deep placement of CaCN₂ or CU-100 for soybean cultivation enabled the supply of N without concomitant depression of N₂ fixation. Thus the deep placement of cheaper CaCN₂ was found to be as effective as that of CU-100 for enhancing the soybean seed yield.     

Selection of a recombinant Marek's disease virus in vivo through expression of the Marek's EcoRI-Q (Meq)-encoded oncoprotein: characterization of an rMd5-based mutant expressing the Meq of strain RB-1B

Marek's disease (MD) is a highly contagious viral disease of chickens (Gallus gallus domesticus) caused by MD virus (MDV), characterized by paralysis, neurologic signs, and the rapid onset of T-cell lymphomas. MDV-induced T-cell transformation requires a basic leucine zipper protein called Marek's EcoRI-Q-encoded protein (Meq). We have identified mutations in the coding sequence of Meq that correlated with virus pathotype (virulent, very virulent, and very virulent plus). The aim of this study was to determine whether recombinant viruses could be isolated based on Meq expression through in vivo selection. Chicken embryo fibroblasts (CEFs) were cotransfected with an rMd5 strain-based Meq deletion virus (rMd5deltaMeq) and meq loci from strains representing different pathotypes of MDV. Transfected CEFs were inoculated into chickens in two independent studies. We were able to isolate a single recombinant virus, rMDV-1137, in a contact-exposed chicken. rMDV-1137 had recombined two copies of the meq gene of RB-1B and was found to have pathogenicity similar to both RB-1B and rMd5 parental strains. We found the RB-1B- and rMd5-induced lymphomas showed differences in composition and that rMDV-1137-induced lymphomas were intermediate in their composition. We were able to establish cell lines from both RB-1B- (MDCC-UD35, -UD37) and rMDV-1137 (MDCC-UD36, -UD38)-induced, but not rMd5-induced, lymphomas. To date, no rMd5- or parent Md5-transformed T-cell lines have been reported. Our results suggest that 1) a recombinant MDV can be selected on the basis of oncogenicity; 2) changes in Meq sequence seem to affect tumor composition and the ability to establish cell lines; and 3) in addition to meq, other genomic loci affect MDV pathogenicity and oncogenicity.     

Isolation, enumeration, and characterization of diazotrophic bacteria from paddy soil sample under long-term fertilizer management experiment

A study was undertaken to determine the free-living culturable diazotrophic bacteria of paddy soils from a long-term fertilizer management experiment. Long-term application of different fertilizers significantly affected the population of free-living diazotrophs. Out of 165 distinct bacterial morphotypes observed during the isolation process, only 32 were positive for both acetylene reduction assay (ARA), and nifH gene screening. The ARA activity of the isolates ranged from 1.8 to 2,844.7 nmol ethylene h^?1 mg protein^?1. The 16S rRNA analysis identified the isolates to be members of 13 different genera viz. Bacillus, Pseudomonas, Paenibacillus, Serratia, Ochrobactrum, Lysinibacillus, Burkholderia, Brevundimonas, Herbaspirillum, Novosphingobium, Sphingomonas, Xanthomonas, and Azorhizobium. Though partial nifH gene sequencing of diazotrophic isolates showed good consistency with that of 16S rRNA-based identification, some nifH sequences were similar to a variety of uncultured nitrogen-fixing bacteria. The diversity of free-living diazotrophic bacteria and the wide distribution of nifH sequences indicate the potential contribution of these microorganisms to nitrogen input to paddy fields.