Enhanced ambient storage stability of an entomopathogenic nematode through anhydrobiosis

Limited shelf‐life is a major obstacle to large‐scale use of entomopathogenic nematodes in biological control. Recently, the development of a water‐dispersible granular formulation (WG) containing entomopathogenic nematodes was described. This paper reports that storage stability of Steinernema carpocapsae Weiser infective juveniles at 25 °C is enhanced from three to six months in this WG. It is also demonstrated that the enhanced stability is achieved through the induction of partial anhydrobiosis that reduces oxygen and lipid reserve utilization by infective juveniles. Nematode infectivity is unaffected during storage under partial anhydrobiosis in the WG formulation. © 2000 Society of Chemical Industry     

Heterochromatin and epigenetic control of gene expression

Eukaryotic DNA is organized into structurally distinct domains that regulate gene expression and chromosome behavior. Epigenetically heritable domains of heterochromatin control the structure and expression of large chromosome domains and are required for proper chromosome segregation. Recent studies have identified many of the enzymes and structural proteins that work together to assemble heterochromatin. The assembly process appears to occur in a stepwise manner involving sequential rounds of histone modification by silencing complexes that spread along the chromatin fiber by self-oligomerization, as well as by association with specifically modified histone amino-terminal tails. Finally, an unexpected role for noncoding RNAs and RNA interference in the formation of epigenetic chromatin domains has been uncovered.     

Polar lipids of sun flower (Helianthus annuus L.) seeds

Qualitative and quantitative analysis of polar lipids in sun flower (Helianthus annuus L.) seed is reported in the present study. Ten classes of polar lipids i.e. phosphatidic acid, phosphatidyl inositol, phosphatidyl choline, phosphatidyl ethanolamine, phosphatidyl glycerol, diphosphatidyl glycerol, digalactosyl diglyceride, monogalactosyl diglyceride, esterified sterol glycoside and free fatty acids have been identified. Phosphatidyl choline and phosphatidyl inositol formed the major phosphatide fractions. Only four fatty acids i.e. palmitic, stearic, oleic and linoleic acids were present in measurable amounts in the total polar lipids. There was a great variation in the fatty acid composition in different classes of polar lipids. Arachidic acid was present in all the individual phosphatide fractions. Phosphatidyl glycerol was highly unsaturated followed by esterified sterolglycoside, phosphatidic acid, phosphatidyl ethanolamine + phosphatidyl glycerol, diphosphatidyl glycerol and monogalactosyl diglyceride.     

Agroforestry systems for soil and water conservation and sustainable production from foothill areas of north India

Some conservation based agroforestry systems (AFS) were developed for possible adoption in place of high risk rainfed farming on land capability classes Ito IV of a typical topo-sequence of foothill north India. The agri-silvi-horticulture system integrating leucaena, lemon, papaya and turmeric on class I irrigated land provided sustainable mean net returns of Rs. 17066 against Rs. 7852 ha.^–1 yr.^–1 from double cropped agricultural system. The intercropping of cluster beans with leucaena gave the highest net returns of Rs. 3540 ha.^–1 yr.^–1 in the agri-silvicultural system adopted on class II land. Eucalyptus terettcornis (Smith) in top and Bhabbar grass (Eulaliopsis binata Retz) in the understorey on a sandy loam class III land gave four years (1985–1988) mean air dry grass yield of 4.2 (used for paper pulp) from October and 1.19 t. ha^–1 yr.^–1 (used for fodder) from June cut. The net returns from grass alone were Rs. 4672 against Rs. 1679 ha.^–1 yr.^–1 from rainfed field crops raised on an adjoining plot. The returns from trees would be additional. Bhabbar grass raised under Acacia species on a 25 to 30% sloping gravelly class IV land provided yield varying from 2.18 to 4.31 from October cut and 0.50 to 1.1 t. ha.^–1 yr.^–1 from June cut with 6 years mean of 3.9 t. ha.^–1 yr.^–1 which at 1988 prices provided net returns of Rs. 2402 ha^–1. These AFS proved superior to traditional farming on each land capability class.     

An association between encephalomyocarditis virus infection and reproductive failure in pigs

An outbreak of reproductive failure, characterised by mummified foetuses and stillbirths, was investigated in an intensive piggery. Six foetuses that died towards the end of gestation had multifocal myocardial necrosis and encephalomyocarditis virus was recovered from 4 of these foetuses but not from 6 mummified foetuses. There was also a significant increase in failure of conception or early embryonic deaths in sows mated at the same time as sows which produced affected litters.     

Induced defense dynamics in plant parts is requisite for resistance to <Emphasis Type="Italic">Helicoverpa armigera</Emphasis> (Hubner) infestation in chickpea

Helicoverpa armigera is the most serious insect pest in chickpea that causes significant yield losses due to its feeding on vegetative (leaves) and reproductive (developing pods and seeds) parts of plants. The present aim of study was to explore response dynamics of induced defence mechanism in leaves, podwall and seeds of ten chickpea genotypes (ICC 506, ICCV 10, ICC 10393, 5283, RSG 963, GL 25016, GL 26054, ICCL 86111, ICC 3137, L 550) after insect infestation. Two chickpea genotypes namely ICC 3137 and L 550 were found to be highly susceptible to Helicoverpa armigera infestation due to higher leaf and pod damage in them as compared to rest of eight genotypes which are found to be considerably resistant due to lower damage. Insect infestation induced decreased activities of defensive enzymes such as peroxidase (POD), catalase (CAT), glutatione reductase (GR) and polyphenol oxidase (PPO), decreased free radical scavenging activities in terms of 2,2-diphenyl-1-picryl hydrazyl (DPPH), decreased contents of signaling molecules such as nitric oxide ((NO), hydrogen peroxide (H₂O₂), reduced content of insect feeding behaviour regulating molecules such as total phenols, trypsin inhibitor and accumulation of membrane damage marker such as malondialdehyde (MDA) in leaves of ICC 3137 and L 550; decreased POD activity, nitric oxide content and H₂O₂ in podwall of L550; decreased SOD, GR, nitric oxide content and H₂O₂ in seeds of L550 resulted in aggravation of infestation induced oxidative stress and makes these genotypes more vulnerable to insect damage. The resistance of rest eight chickpea genotypes to insect infestation was due to the integrative effect of up regulated defensive components in leaves, podwall and seeds such as enhanced activities of CAT, POD, GR, PPO and PAL along with accumulation of H₂O₂` and total phenols in leaves, increased SOD, POD, GR and PPO activities along with increased contents of trypsin inhibitor and total phenols in podwall; increased SOD, GR, PPO activities and accumulated total phenols in seeds of resistant chickpea genotypes might be responsible for causing significant shift in oxidative status of these genotypes due to scavenging of free radicals, maintenance of membrane integrity and deterrent to insect feeding. Induced glycine betaine after herbivory was found to be positively correlated with superoxide dismutase and trypsin inhibitors. H₂O₂ content was positively correlated with trypsin inhibitor, DPPH, ferric reducing antioxidant power (FRAP) and total phenols in leaves and with FRAP, DPPH and total phenols in pod wall indicating that H₂O₂ might be stimulating the cascade that will be helping to scavenge free radical species and correlation with phenols and trypsin inhibitor indicated that it act as toxicant to insect feeding.     

Water uptake, water use efficiency, plant growth and ionic balance of wheat, barley, canola and chickpea plants on a sodic vertosol with variable subsoil NaCl salinity

Salinity in topsoil and subsoil is one of the major abiotic environmental stresses to crop production. To investigate the comparative tolerance ability of wheat, barley, canola and chickpea to subsoil NaCl salinity and its impact on water uptake, water use efficiency, plant growth and ionic balance, a pot experiment was conducted on a heavy texture soil (sodic vertosol) having 20 ESP (exchangeable sodium percentage), 3.5 dS/m EC_e and 400 mg/kg Cl with additional NaCl applied in subsoil at 500, 1000, 1500 and 2000 mg/kg soil. Plants were harvested 40 days after sowing and assessed for different parameters. Increasing levels of subsoil NaCl salinity had significant depressing effect on shoot and root biomass, root/shoot ratio, water uptake and water use efficiency (shoot biomass production with a unit amount of applied water), leaves K:Na ratio and Ca:Na ratio of all the four species, but the magnitude of effect varied considerably among the species. Chickpea was affected most followed by wheat, barley and canola at the highest level of subsoil NaCl salinity. There was 64%, 49%, 37% and 34% reduction in shoot dry weight of chickpea, wheat, barley and canola respectively by highest subsoil salinity. Similarly water uptake declined by 61%, 36%, 31% and 26% respectively in chickpea, wheat, barley and canola. Water use efficiency of four species was in order of barley > canola > wheat > chickpeas on this sodic vertosol. The cumulative effects of reduced osmotic potential of soil solution, ion toxicity (high concentrations of Cl and Na) in soil/plants and ionic imbalance (reduced K:Na and Ca:Na ratio) within plant system under increased subsoil NaCl salinity contributed to reduce water uptake and plant growth in all the four crops, and the effects were more severe in chickpeas. Wheat despite having considerably lower Na and Cl in their leaves suffered greatly in plant growth and water uptake compared with barley and canola indicating better tolerance ability of barley and canola to high Cl and Na build up at tissue level. Results suggest chickpea to be the most sensitive to subsoil NaCl salinity. The growing of comparatively tolerant species like barley and canola may be the better option for sustaining crop production and higher water use efficiency on sodic vertosols with high subsoil NaCl salinity.     

Substitution of nitrogen requirement of maize through leaf biomass of Leucaena leucocephala: agronomic and economic considerations

In a 3-year field study, the effects of substitution of nitrogen requirement of maize through Leucaena leaves were studied on runoff, soil loss, maize and wheat yield and economic returns. The treatments were (1) 80 kg N ha^-;1 all through Leucaena leaves (80 L), (2) 40 kg N through Leucaena leaves + 40 kg N ha^-;1 through fertilizer (40 L + 40 F), (3) 20 kg N through Leucaena leaves + 60 kg N ha^-;1 through fertilizer (20 L + 60 F), (4) 80 kg N ha^-;1 all through fertilizer (80 F), and (5) control (No fertilizer). Green Leucaena leaf biomass (containing 3.3% N on dry basis) was incorporated every year in 15 cm top soil two weeks before sowing of summer maize.Other treatments being almost equal, runoff was reduced marginally in treatment 20 L + 60 F which was attributed to better crop growth in this treatment. Mean minimum soil loss (6.202 t ha^-;1) also occurred in treatment 20 L + 60 F. Soil loss in 80 L was 13% less than in 80 F. Maize yield was at par in 80 L and 80 F. However, mean maximum yield of maize was obtained with 20 L + 60 F.Residual effect of incorporation of Leucaena leaves to maize crop was observed on wheat yield. The mean yield differences were statistically at par in all the treatments except control. The total mean net returns were statistically at par in 80 L and 80 F. However, significantly higher mean net returns (Rs 6811 ha^-;1; one US$ = Rs30) were obtained with 20 L + 60 F. Substitution of N through Leucaena leaves even in small quantity may be helpful to small holders, particularly where chemical fertilizers are in short supply or too expensive.     

A single recessive gene for stem sweetness in sorghum

Summary The inheritance of stemsweetness in sorghum has followed a qualitative pattern, non-sweet being monogenically dominant over sweet. Hence sweetness was controlled by a single recessive gene. A maternal effect was not involved for the expression of sweetness.