Enzyme‐producing bacteria isolated from fish gut: a review

Digestion of food depends on three main factors: (i) the ingested food and the extent to which the food is susceptible to the effects of digestive enzymes, (ii) the activity of the digestive enzymes and (iii) the length of time the food is exposed to the action of the digestive enzymes. Each of these factors is affected by a multitude of secondary factors. The present review highlights the experimental results on the secondary factor, enzymatic activity and possible contribution of the fish gut microbiota in nutrition. It has been suggested that fish gut microbiota might have positive effects to the digestive processes of fish, and these studies have isolated and identified the enzyme‐producing microbiota. In addition to Bacillus genera, Enterobacteriaceae and Acinetobacter, Aeromonas, Flavobacterium, Photobacterium, Pseudomonas, Vibrio, Microbacterium, Micrococcus, Staphylococcus, unidentified anaerobes and yeast are also suggested to be possible contributors. However, in contrast to endothermic animals, it is difficult to conclude the exact contribution of the gastrointestinal microbiota because of the complexity and variable ecology of the digestive tract of different fish species, the presence of stomach and pyloric caeca and the relative intestinal length. The present review will critically evaluate the results to establish whether or not intestinal microbiota do contribute to fish nutrition.     

Host and virus effects on reversion in cassava affected by cassava brown streak disease

The phenomenon of virus‐infected plants naturally recovering health is known as ‘reversion’, and is a type of resistance mechanism exploited in some crop plants for disease control. Various parameters were investigated that affect reversion from cassava brown streak disease (CBSD) in three cassava varieties (Albert, Kaleso and Kiroba) that differ in levels of resistance to the disease. Cassava plants were inoculated by grafting with two virus species (Ugandan cassava brown streak virus, UCBSV and Cassava brown streak virus, CBSV) that cause CBSD, and the plants grown from them were subsequently assessed for reversion. The rate of reversion depended on the cassava variety, virus species, and the length and position of the stem cuttings used. A significantly high proportion of progenies were virus‐free (reverted) for the resistant variety Kaleso (64·1% for UCBSV and 54·9% of CBSV), compared to the tolerant variety Kiroba (56·7 and 45·5%) and the susceptible control Albert (38·9 and 35·1%). The highest number of virus‐free plants was generated from short 10 cm long cuttings (e.g. 60·1% for Kaleso for CBSV) compared to 20 cm long stem cuttings (e.g. 21·4% for Albert). Cuttings taken from upper stems of diseased plants produced most virus‐free progenies compared to middle and lower parts. More than 50% virus‐free plants were obtained in the resistant and tolerant varieties. This is a highly valuable finding and could be exploited for developing strategies to control the current CBSD epidemic in eastern and central Africa.     

Resistance of Scots pine (Pinus sylvestris L.) wood modified with functionalized commercial silicone emulsions against subterranean termites

Scots pine (Pinus sylvestris L.) sapwood was treated with quat-silicone micro-emulsion (<40?nm), amino-silicone macro-emulsion (110?nm), alkyl-modified silicone macro-emulsion (740?nm) and solutions of inorganic water glass. Three treatment concentrations of 5, 15 and 30% (w/w) were used for the impregnation of the test specimens. Termite resistance was assessed following a 16-week field trial conducted in northern Queensland, Australia. Two different field sites were chosen for exposure to feeding by Coptotermes acinaciformis (Froggatt) and Mastotermes darwiniensis (Froggatt). Following exposure, the test and feeder specimens were inspected and assessed for termite damage using a visual rating system (from 10 sound to 0 completely destroyed) and individual mass losses. The specimens treated with quat- and amino-silicone emulsions resisted damage by both termite species, even at less than 15% weight percent gains (WPGs). Alkyl-modified silicone macro-emulsion and water glass treatment induced somewhat less resistance to termite damage, but imparted protection at higher WPGs.     

Maternal influence on diapause induction: an approach to improve long-term storage of <Emphasis Type="Italic">Trichogramma chilonis</Emphasis>

We have investigated the role of the thermo-photoperiodic condition of maternal generation in diapause induction of Trichogramma chilonis (Ishii) (Hymenoptera: Trichogrammatidae) lab strain. To test the maternal effect, two lines of T. chilonis lab strain were generated by rearing them for one generation at: (1) 15 °C with L:D-12:12 (¹⁵F-1₁₂) and (2) 15 °C with L:D-20:4 (¹⁵F-1₂₀). The laboratory strain reared at 15 °C with L:D-12:12 for 65 generations (¹⁵F-65₁₂) was used as the control (acclimatized strain) due to its proven diapausing capacity. The ¹⁵F-1₂₀ line failed to undergo diapause, though healthy pre-pupae were formed at the pre-storage condition (at 10 °C with L:D- 8:16 and RH-60-70%). However, ¹⁵F-1₁₂ line could successfully complete all the phases of diapause and was comparable with the control batch. Considering 50% adult emergence and minimum 3 days of longevity, 125 days of storage could be achieved. From our current study, we conclude that diapause can be induced in T. chilonis lab strain by providing appropriate thermo-photoperiod to their maternal generation (for a single generation) followed by suitable diapause inducing and terminating protocols.     

Effect of Compost and Hydroabsorbent Polymer on Tree Growth and Soil Properties in a Tropical Urban Environment

Horticultural application of hydroabsorbent polymer (HP) has drawn research attention due to its perceived benefits to plant growth. Few studies have compared the use of compost and HP amendments on tree establishment in tropical urban environments. An experiment was conducted to assess the effect of compost (40% v v^–1) and HP (3 and 5 kg m^–3) on the growth of two native tree saplings (Calophyllum soulattri and Syzygium myrtifolium) in loamy and sandy soils. The HP treatments significantly affected soil pH and extractable phosphorus (P) and potassium (K), whereas combined application of compost and HP (5 kg m^–3) resulted in significantly higher nitrogen (N) in both soil types. Plant diameter and height were significantly higher following HP application. This experiment demonstrates the efficacy of HP that can cater the plant requirements at the initial growth stages which are crucial for their successful establishment in tropic urban degraded soils.     

Community Forestry in the State of Uttarakhand,India: Not Meeting the Needs of the Villagers

This community forestry case study examines village forest councils (van panchayat) in India’s northern state of Uttarakhand. We describe forest stocking levels of 20 community forests and address the question of whether these forests are in a position to provide commodity resources, such as fuelwood and fodder, on a sustainable basis. In addition, we report on the perceptions of the villagers on whether their respective community forest is meeting their fuelwood and fodder needs. At the biophysical level, none of the community forests were in a position to provide fuelwood and fodder on a sustainable basis. Most forests did not have adequate overstory stocking, and there was no evidence of deliberate management to improve the situation. Interviews with 400 villagers (20 in each village) supported the field findings. Villagers unanimously reported that their respective community forest was inadequate in supplying commodity needs. Furthermore, they wished the Forest Department would provide more technical and financial assistance to guide them with forest management needs. Women are a critical part of community forestry as they are the primary gatherers of fuelwood and fodder. Although the perceptions of women toward forest management issues are important, our interviews with female villagers indicate they play a passive role in decision-making. Decentralization in natural resources management sounds good at the theoretical level as it provides villagers with some authority and autonomy, but it cannot be effectively implemented without professional guidance coupled with resources. The villagers are ready and willing to improve the situation, but they do not have the resources to make change unilaterally—they need professional and financial support from the Forest Department.     

Ovsynch Plus protocol improves ovarian response in anovular Murrah buffaloes in low‐breeding season

The objective of the study was to evaluate the efficacy of ovarian response and pregnancy rate in anovular buffaloes following Ovsynch and Ovsynch Plus protocols. Buffaloes (n = 55) were divided into two groups: Ovsynch group (n = 26): GnRH (10 μg, GnRH1) on Day 0, PGF₂α (25 mg) on Day 7, GnRH (10 μg, GnRH2) on Day 9; Ovsynch Plus group (n = 29): 500 IU equine chorionic gonadotropin (eCG) 72 hr (day ?3) prior to Ovsynch protocol, followed by fixed timed artificial insemination (FTAI) 6 and 24 hr after GnRH2 injection in bot groups. Transrectal ultrasonography was performed daily, that is, from day 0 and ?3 in Ovsynch and Ovsynch Plus group, respectively for ovarian response and pregnancy diagnosis at day 30 post‐insemination. In Ovsynch Plus group, administration of eCG prior to GnRH1 increased (p < .001) the diameter (mm) of dominant follicle (DF) from 10.15 ± 0.26 to 12.23 ± 0.34 within 72 hr of treatment resulting higher ovulatory response to GnRH1. Ovulation after GnRH1 was higher (p < .01) in Ovsynch Plus group (96.6%) than Ovsynch group (61.5%). However, ovulation rate to GnRH2 was similar (p > .05) between groups (Ovsynch group: 76.9% vs. Ovsynch Plus group: 70.0%). Mean DF diameter (mm) that ovulated to both GnRHs was higher (p < .01) than non‐ovulated counterparts in both groups (Ovsynch group: 10.80 ± 0.27 vs. 8.47 ± 0.53; Ovsynch Plus group: 11.99 ± 0.24 vs. 9.5 ± 0.63). Pregnancy was established in buffaloes which responded to both GnRHs, irrespective of groups, being higher (p = .52) in Ovsynch Plus group (34.5%) than Ovsynch group (23.1%), though non‐significant. In summary, this study showed that eCG inclusion prior to Ovsynch regimen improves ovulatory response in anovular buffaloes during low‐breeding season.     

Variability among isolates of <Emphasis Type="Italic">Fusarium udum</Emphasis> and the effect on progression of wilt in pigeonpea

Soft rot of Chinese cabbage is a disease of great economic importance to the State of Pernambuco, Brazil. The present study aimed to evaluate the effect of two calcium sources in different concentrations (calcium nitrate [Ca(NO₃)₂] at 0, 0.15 and 0.3 g l^?1 and calcium chloride (CaCl₂) at 0, 1 and 5 g l^?1) that were applied through two methods (leaf spraying and soil drenching) on the control of soft rot. Further, it aimed to analyze calcium absorption by the plant and to determine calcium’s role in leaf and cell structure using microscopy. Ca(NO₃)₂ applied by both methods was effective in controlling soft rot caused by Pectobacterium carotovorum subsp. carotovorum, as it reduced the disease by up to 48.5 % when sprayed onto the leaves (0.15 g l^?1). A significant increase in the leaf calcium content was observed only in the plants that were sprayed with higher doses of Ca(NO₃)₂ and CaCl₂. In all of the calcium treatments, light microscopy analyses revealed an increased number of chloroplasts and improved structuring of the palisade parenchyma, while transmission electron microscopy analyses revealed an increased cell wall thickness that was especially evident for the 0.15 g l^?1 Ca(NO₃)₂ treatment applied by leaf spraying and soil drenching.     

An integrated approach to weed management practices in direct-seeded rice under zero-tilled rice–wheat cropping system

An increasing water crisis as well as shortage of farm labor farmers in many Asian regions is forcing a shift from puddled transplanted rice to direct-seeded rice. The weeds, however, are a major constraint to the production of direct-seeded rice. In this perspective, a field study was carried out to evaluate various pre- and post-emergence herbicides and different possible integrated weed management practices in zero-till direct-seeded rice. Weed infestation decreased the rice yield by near about 75%. Co-culture rice with Sesbania followed by (fb) pendimethalin fb 2,4-D effectively reduced the total weed population (65.1%) and biomass (86.7%) at 30 days after sowing (DAS). The lowest total weed dry biomass at 60 DAS was recorded from bispyribac-sodium+azimsulfuron-treated plot and such tank mix application of herbicide performed better against diverse weed flora as compared to a single herbicide. Higher yield and more profit from zero-till direct-seeded rice were obtained with the application of bispyribac-sodium+azimsulfuron herbicides as a tank mixture or an integrated approach through cowpea green-manuring fb 2,4-D+glyphosate fb bispyribac-sodium by effective management of versatile weed flora.