In vitro somatic embryogenesis in callus cultures of Azadirachta indica A. Juss.—a multipurpose tree

Plant regeneration via somatic embryogenesis was achieved in embryogenic callus cultures derived from immature zygotic embryos 40 days after anthesis of Azadirachta indica A. Juss. on semisolid basal Murashige and Skoog (MS) salts and vitamins supplemented with 1.11 µM 6-benzylaminopurine (BA) and 4.52–6.78 µM 2,4-dichlorophenoxyacetic acid (2,4-D). The globular-stage embryos were induced when the callus was transferred to medium with 1.11 µM BA and 0.45 µM 2,4-D. The highest average number of somatic embryos per 200 mg of callus was 152.8 after 8 weeks of culture on the medium. Maturation and germination of the somatic embryos were achieved on half-strength MS salts and vitamins supplemented 0.38–0.94 µM abscisic acid (ABA) and 2% (w/v) sucrose. The maximum percentage (64.2%) of germination was obtained with 0.94 µM ABA within 2 weeks of culture. Somatic embryo-derived plantlets were acclimatized in a greenhouse and subsequently showed normal growth. This efficient protocol will be helpful for propagating elite clones on a mass scale and will also be useful for genetic transformation study.     

Heterosis for leaf photosynthesis,grain yield and yield components in maize

Summary One of the primary avenues of improving the biological efficiency of crop plants is through the improvement of the leaf and canopy photosynthetic rates. However, the question whether the superiority of hybrids in respect of productivity potential could be traced, in retrospective fashion, to the photosynthetic parameters should be answered first. Once established and standardized, such indices could be streamlined in innovative breeding to predict the heterotic combinations for final yield formation. To answer this question, the photosynthetic rate and other components of photosynthetic efficiency were monitored among eight inbred stocks of maize (selected for variable photosynthetic rate from a previous study) and their all possible one-way crosses. The results demonstrated extensive heterosis in respect of photosynthetic rate and other photosynthetic indices which, in turn, was also realized in terms of higher biomass productivity and yield. Nonetheless, high leaf photosynthesis alone did not result in higher grain yield. On the contrary, component interaction among the photosynthetic indices like photosynthetic rate, leaf area/plant, number of leaves and chlorophyll content on one hand and the complementary gene action on the other, could be held responsible for higher yields in hybrids. Since the components of photosynthetic efficiency can predict heterosis for biomass and grain yield upto a reasonable extent, judicious incorporation of such indices in selection parameters for applied genetic protocols can add yet another dimension to the strategies for future yield improvements.     

Long-term farmyard manure application effects on properties of a silty clay loam soil under irrigated wheat–soybean rotation

Increasing importance has been placed on the use of agricultural soils for the mitigation of atmospheric CO₂ through sequestration of soil C. Although crop productivity is sustained mainly through the application of organic manure in the Indian Himalayas, little information is available on C sequestration, C content in different aggregate size fractions and soil water transmission properties (infiltration and saturated hydraulic conductivity) as affected by long-term manure addition. We analyzed results of an 8-year experiment, initiated in 1995–1996 on a silty clay loam soil, to determine the influence of fertilizer and fertilizer + farmyard manure (FYM) application on those important soil properties. The overall increase in soil organic C (SOC) content in the 0–45 cm soil depth in NPK + FYM treatment as compared to NPK and control treatments was 11.0 and 13.9 Mg C ha⁻¹ at the end of 8 years, respectively. Application of FYM significantly reduced soil bulk density and increased mean weight diameter (MWD) and SOC contents in different aggregate size fractions. Soil organic C content in macroaggregates was greater than in microaggregates. The response of SOC content to FYM application was dependent upon inorganic fertilization and more upon balanced application of NPK than N only. Steady state infiltration rate under NPK + FYM (1.98 cm h⁻¹) was higher than under unfertilized (0.72 cm h⁻¹) and NPK (1.2 cm h⁻¹). Soil water sorptivity (calculated from Philip's equation) under NPK + FYM (1.06 cm min^−0.5) was higher than under NPK (0.61 cm min^−0.5). We conclude that hill farmers in northern India should be encouraged to use FYM along with chemical fertilizers to increase SOC content and improve soil physical properties.     

Epidemiological study of parasite infection in a cow-calf beef herd in Quebec.

The patterns of gastrointestinal and pulmonary nematode infections in a previously untreated Aberdeen Angus cow-calf herd were observed between May 1988 and December 1990. The cow-calf herd and replacement heifers were on separate pastures. The relatively high mean faecal egg counts of cows and heifers at the time of turnout were mainly owing to the maturation of hypobiotic worms. The strongyle egg counts of calves began to rise soon after turnout onto pasture and reached peak levels at the end of the grazing season. The number of infective larvae on pasture was highest during September/October. Ostertagia, Cooperia and Nematodirus were the most prevalent genera found at necropsy and on pasture. Larvae of these nematodes were able to overwinter on pasture and Ostertagia larvae, additionally, were able to overwinter in the host as arrested early fourth stage larvae. The high egg output of cows at the time of turnout may serve as a source of infection for their calves and be responsible for the late-season rise in pasture larval counts.     

L-Ascorbic acid (vitamin C) supplementation to optimize health and reproduction in cattle

Cattle can synthesize L-ascorbic acid (or Vitamin C) from either D-glucose or D-galactose through glucuronic acid pathway in the liver. L-Ascorbic acid present in cattle diet is almost totally destroyed by rumen microorganisms making them essentially dependent on its endogenous synthesis, which is assumed sufficient to meet the physiological requirement. Therefore, the role of vitamin C in cattle health and disease has remained widely overlooked. However, there is mounting evidence that the level of L-ascorbic acid in blood and other tissues decreases in association with stress and disease, and Vitamin C supplementation revealed favorable response as evident from early recovery. The present review is an attempt to summarize the existing literature pertaining to the physiological role of L-ascorbic acid and the scope of its supplementation in the prevention and treatment of diseases in cattle. It should be realized that the aqueous solution of vitamin C is highly acidic and subcutaneous or intramuscular administration may cause tissue irritation and inflammation, whereas the sodium ascorbate solution is less acidic and might be used for intramuscular administration.     

Self-generated microbial population or cultured microflora – an important criterion toward development of an effective and economically viable road map for organic soil management

Huge depletion of soil microflora under conventional farming practice has become the primary contributory factor toward the present depletion of soil and crop productivity. Reconstitution of soil microbial dynamics has been identified as the only way out, but there has been a debate regarding the most effective pathway for soil rejuvenation i.e. whether to create the environment for natural proliferation or opt for inoculation of laboratory generated microbes. In this respect, a study was undertaken at Maud T.E. (Assam) under FAO-CFC-TBI Project, where bio-fertilizer (microbial inoculant, MI), vermicompost (organic food source, OF), vermicompost + bio-fertilizer (OF+MI), and Novcom compost (representing self-generated native microflora in the order of 10¹⁶c.f.u. along with organic food source, SNM); were taken as treatments for a yield target of 1500 kg made tea/ha. The highest crop yield (1500 kg ha^?1) along with high and consistent soil quality development was noted under SNM treatment; while MI influenced lowest yield (1268 kg ha^?1) and minimal soil response. Addition of the organic food source with cultured microbes (MI+OF) was found to improve crop performance (1427 kg ha^?1), but with 7.60 times higher cost (Rs. 39.97 kg^?1 made tea). Economic viability study indicated that except SNM, all other treatments were vulnerable toward crop loss or market downfall.     

Effect of dietary utilisation of sugarcane press mud on production performance of Muzaffarnagari lambs

Sugarcane press mud (SPM) is one of the potential agro-industrial by-products available in India and research exploring its utilisation in small ruminant nutrition is scanty. In this direction, the present study evaluated the feasibility of dietary incorporation of SPM at different levels in a feeding trial lasting 180 days. A total of 21 Muzaffarnagari ram lambs were randomly distributed into three groups of seven each based on comparable body weight (11.70 ± 0.29 kg) and age (3–5 months) following a completely randomised design. The three dietary treatments were (1) SP₀ (control), concentrate mixture without SPM; (2) SP₁₀, concentrate mixture comprising 10% SPM and (3) SP₂₀, concentrate mixture comprising 20% SPM on air-dry basis. The experimental lambs were offered weighed quantity of designated isonitrogenous (crude protein = 20.6%) and isoenergetic (metabolisable energy = 12.1 MJ/kg) concentrate mixture (coarse mash) and along with ad libitum wheat straw (threshed to 1–2-cm length) and a 9-day metabolism trial was conducted. Results revealed no significant (P > 0.05) differences in intake and digestibility of nutrients, nitrogen balance, nutritive value of diets, average daily gain, as well as feed conversion ratio among three groups. The serum concentration of triiodothyronine and tetraiodothyronine did not differ due to treatments. Likewise, wool yield and its quality, measured in terms of fibre diameter, medullation percentage and staple length were also comparable irrespective of dietary variation. Furthermore, the cost of concentrate mixture (Rs/day) was lower (P ≤ 0.05) in SP₂₀ followed by SP₁₀ as compared to group SP₀. These findings suggested that SPM could be safely fed up to 20% level in the concentrate mixture for lambs substituting expensive traditional feed ingredients without negatively inflicting the performance of growing lambs.     

Risk analysis of non-native three-spot cichlid,Amphilophus trimaculatus, in the River Cauvery (India)

The three-spot cichlid Amphilophus trimaculatus (Günther) is an ornamental fish known to be invasive but has not been assessed for India. The present study confirmed this non-native species’ identity using conventional and molecular methods, as well as its occurrence in the River Cauvery, the first for this species in a lotic environment outside its native range. Gut content analysis indicated a diet of predominantly insects. The river's water quality and habitat were conducive for the species’ growth and reproduction. Using the Aquatic Species Invasiveness Screening Kit, A. trimaculatus was ranked as posing a “high” risk of being invasive in the River Cauvery, with climate match analysis showing 58% similarity with the species’ native range. Vector and pathway analysis found that A. trimaculatus was introduced to India via the aquarium trade, although consignment origin remains unknown, and the most likely means of entry into the river and its tributaries was the species’ escaping from holding facilities. Subsequent dispersal and impact of the species on native fauna are discussed. The study's outcomes demonstrate the importance of using risk analysis protocols to inform management of non-native species in India, with suggestions provided for immediate and long-term measures for the species’ management.