Development of Eco-friendly and Non-hazardous Weed Control Technology for Lowland Rice by Smothering through LDPE Film

Intensive use of chemical herbicides and pesticides has raised serious concern about their effect on non-target organisms, plants, human bodies and the environment. Hence there is a continuous search for benign, harmless, non-hazardous and eco-friendly technology to control the growth of weeds which compete with crops for water, nutrients, light and space; thus reducing crop yield significantly. An attempt was made to control the weeds through smothering. This controls the weeds by cutting off light from the photosynthetic portion of weed plants by using black polyethylene sheets (LPDE film) which inhibit the top growth. Experiments to control the weeds in a lowland rice field through smothering were conducted in the high rainfall coastal region of eastern India wth eight treatments including smothering and conventional methods like hand/mechanical weeding and herbicides, etc. The treatment of smothering for one week + puddling + transplanting proved to be better than other conventional methods and may replace herbicide and hand/mechanical weeding totally with a better rice yield.     

Physiological Factors Limiting Grain Growth in Wheat Ears Cultured in Sucrose Solution

Detached wheat ears (15 days post-anthesis) were cultured in liquid nutrient medium containing different sucrose concentrations (2. 6 and 10%). The volume of solution taken up was highest from 2% sucrose solution and decreased with increasing sucrose concentration. Grain development in terms of grain weight, glumes and rachis weight, nitrogen and protein content showed a linear increase in these variables over 11 days. Dry weight per grain increased with the sucrose level in the medium and the reduced uptake of solution did not decrease the moisture percentage of the grain. The culture of ears decreased the solution pH more with 2% than with 10% sucrose. Addition of 0.5% chloramphenicol to the culture solution had no adverse effect on grain weight, rather it prevented contamination and maintained a higher pH of the solution.     

Pathotyping and antimicrobial susceptibility testing of Escherichia coli isolates from neonatal calves

Neonatal calf mortality is a major concern to livestock sector worldwide. Neonatal calf diarrhoea (NCD), an acute severe condition causes morbidity and mortality in calves. Amongst various pathogens involved in NCD, E. coli is considered as one of the major causes. The study was targeted to characterize E. coli isolates from neonatal calves for diarrhoeagenic Escherichia coli (DEC) types (pathotyping), antimicrobial resistance (AMR) profiling and to correlate with epidemiological parameters. From neonates, a total of 113 faecal samples were collected, out of that 308, lactose fermenting colonies were confirmed as E. coli. Pathotypable isolates (12.3%) were represented by STEC (6.1%), EPEC (2.9%), ETEC (1.9%), EAEC (0.9%) and EHEC (0.3%). Occurrence of STEC was more in non-diarrhoeic calves, whereas ETEC was observed more in diarrhoeic calves. EPEC occurrence was observed in both diarrhoeic and non-diarrhoeic calves. Fishers extract test showed no significant association for occurrence of DEC types to type of dairies, health status, species, breed, age and sex of neonatal calves. Two hundred and eighty isolates were tested for antimicrobial susceptibility. The isolates showed maximum resistance towards ampicillin (55.4%) followed by tetracycline (54.3%), while minimum resistance was observed towards meropenem (2.5%). Multidrug resistant E. coli isolates were found to be 139 (49.6%), and Extended-spectrum beta-lactamase (ESBL) producers were 120 (42.9%). DEC pathotypes like STEC, ETEC, EHEC and EAEC that are also multidrug resistant present in neonatal calves have zoonotic potential and hence are of public health significance.

     

Intercropping field crops between rows of Leucaena leucocephala under rainfed conditions in northern India

A field study was conducted for six years (1981–1986) on sandy loam soil on intercropping hedgerows of Leucaena leucocephala (Lam) de Wit. with three field crops viz. maize (Zea mays L), black gram (Vigna mungo L) and cluster bean (Cyamopsis tetragonoloba L Taub.). In treatments 1 and 2 Leucaena hedges were planted as pure crops at close (25 cm × 75 cm) and wide (25 cm × 375 cm) spacings. In treatments 3, 4 and 5 the three field crops were intercropped between the hedgerows of Leucaena at the wide spacing, and in treatments 6, 7 and 8 the field crops were raised as pure crops. Leucaena was topped to 75 cm each time it attained a height of 175 cm. The pure crop of Leucaena at close spacing produced an average, over the six years, of 34 t ha⁻¹a⁻¹ of green fodder and 9.4 t ha⁻¹a⁻¹ of air dry fuelwood. The Leucaena at wide spacing produced 18.9 t ha⁻¹a⁻¹ of green fodder and 6.3 t ha⁻¹a⁻¹ of fuelwood. Intercropping with field crops decreased the yield of green fodder and fuelwood. The yield of all the field crops was less when raised as intercrops than as pure crops. Mean maximum net returns were obtained from intercrops of Leucaena and cluster bean (Rs 3540 ha⁻¹a⁻¹) which were significantly higher than the returns from pure crop of Leucaena at wide spacing but similar to the returns from pure crops of cluster bean. Leucaena with maize (Rs 3273 ha⁻¹a⁻¹) and black gram (Rs 3125 ha⁻¹a⁻¹) gave significantly higher net returns over pure crops of Leucaena at wide spacing, maize and black gram. ICRISAT = International Crops Research Institute for the Semi-Arid Tropics- Hyderabad, India. CIAT = Centro International de Agricultura Tropical - Cali - Columbia     

Status of agroforestry education in India

India is perhaps the world leader in development of agroforestry education, training and research. The Indian Council of Agricultural Research sanctioned an All-India Coordinated Research Project on agroforestry in 1983, to be headquartered in Delhi but with research centers in 20 other locations countrywide. The agricultural universities in India have a major role to play, with all institutions having agroforestry teaching programs by 1990. At this point there is a great shortage of faculty trained in agroforestry. Demand for qualified graduates with this training is only going to increase.     

An agroforestry practice for the development of salt lands usingProsopis juliflora andLeptochloa fusca

High salt concentration in the soil is a serious problem in vast areas of otherwise productive agricultural lands in India. Establishment of salt tolerant vegetation could be an effective way of ameliorating this problem. In an 8-year field trial on an alkali soil, growth and biomass production ofProsopis juliflora was greater in sole stand than when interplanted with the grassLeptochloa fusca, but soil improvement was greater for the mixed tree-grass treatment.Prosopis accumulated substantially more biomass nutrients when in sole stand, but total nutrient recycling was similar with and without grass. Less salt tolerant but more palatable fodder crops such asTrifolium resupinatum, T. alexandrium andMelilotus denticulata were successfully grown withProsopis after removingL. fusca in theProsopis plus grass treatment 50 months after commencement. Tentative economic analysis suggests theProsopis plus grass system gives higher returns. TheProsopis-Leptochloa system combines production with biological reclamation, and is an appropriate form of reclamation agroforestry for alkali lands.     

Variation in drought response of sal (Shorea robusta) seedlings

Plant development and distribution in areas with seasonal rainfall are often related to the ability of plants to postpone desiccation or tolerate low water potentials during drought. Regeneration of Shorea robusta Gaertn. (sal), a commercially valuable, widely distributed tree of the Indian tropical belt, is unsuccessful at the base of the Himalaya. Seedling shoots die back repeatedly during the long drought that follows the monsoon rain. During the course of one year, we monitored changes in plant and soil water potentials (Psi), leaf conductance (gw), osmotic and elastic adjustment, and xylem conductance of sal seedlings of different sizes from three landforms: an alluvial plain at 540 m elevation, a slope at 510 m, and a montane site at 1370 m. Predawn plant Psi and gw were lowest in the smallest seedlings (< 20 cm tall). Across sites and seasons, seedlings > 100 cm tall had higher morning gw than seedlings in the other size classes. In all size classes, plant Psi was lowest during early summer, when leafing begins. Among sites, Psi and gw were lowest in seedlings at the montane site. Osmotic potential was lowest during leaf development and highest during the rainy season, and tissue elasticity was highest during winter. As leaf area increased during leaf development, xylem conductance per unit of xylem cross-sectional area also increased. We conclude that low Psi is unlikely to be a major cause of seedling mortality. Small seedlings, with low Psi, had low leaf conductance. Adjustments of osmotic and elastic properties appear to aid responses of seedlings to drought.     

Crop productivity under differently lopped canopies of multipurpose trees in Central Himalaya, India

Ficus species are multipurpose trees well known by rural populations in Sahelian and Sudanian zones of Africa. Their uses are well documented but their amenability for vegetative propagation has not been extensively studied. This paper compares the rooting ability of stem and aerial root cuttings from thirteen Ficus species found in West Africa. It highlights the differences between species belonging to the sub-genera Sycomorus and Urostigma. The former show no capacity to propagate from cuttings whereas the latter, with epiphytic development, can be propagated by cuttings, although this capacity varies among species. Thus, F. thonningii, F. leprieurii and F. ovata are easily propagated, while F. platyphylla and F. elasticoides are propagated with difficulty. The rooting capacity also varies depending on the cutting material used. It decreases in the following order: long leafless hardwood cuttings (pole) > nodal cuttings > apical cuttings. Rooting potential increases when the cuttings are harvested towards the end of the dry season(March to May). Aerial root can be used for cuttings in all species of the sub-genus Urostigma. The capacity of root cuttings to regenerate is greatest when cuttings are collected at the beginning of the dry season (November). In this case, wound-induced adventitious roots arise at the basal end of the cutting while de novo buds are developed from the cambium at the distal end. The subsequent morphological development is identical to that of a stem cutting. These results clarify and allow the optimal use of the knowledge and methods developed by the indigenous people of the Sahel and could assist and promote fig tree (Ficus sp.) domestication in the dry tropics.This revised version was published online in November 2005 with corrections to the Cover Date.