Assaying the allelopathic effects of <Emphasis Type="Italic">Eucalyptus camaldulensis</Emphasis> in a nursery bed incorporated with leaf litter

Allelopathic effects of Eucalyptus camaldulensis Dehnh. were confirmed in Petri dish and pot experiments in our previous studies. However, the degree to which such effects under controlled experiments exist in more complex ecological settings remains to be tested. Thus, the present study was carried out by incorporating different proportions of ground litter of E. camaldulensis in soil. The growth of three agricultural crops: falen (Vigna unguiculata (L.) Walp.), chickpea (Cicer arietinum L.), and arhor (Cajanus cajan (L.) Millsp.), and two tree species, kala koroi (Albizia procera (Roxb.) Benth.) and ipil ipil (Leucaena leucocephala (Lam.) de Wit) were tested. There were inhibitory effects of leaf litter on germination, shoot and root growth, leaf number, and collar diameter as well as a reduction of nodulation by legume crops (25–80% reduction). The extent of the effects was dependent on the proportion of leaf litter, the species and the type of traits. In contrast to shoot growth, the effect on root growth was more severe. No effect on germination was found with the agriculture crops while the two tree species showed reduced germination. The effect was greater in the presence of higher proportions of leaf litter mixed in soil while in some cases lower proportions stimulated growth. Not all species were suppressed; A. procera, C. cajan, V. unguiculata showed compatible growth while C. arietinum and L. leucocephala were found incompatible. This study provides evidence that E. camaldulensis has allelopathic potential under field conditions and a careful selection of associated crops in agroforestry systems is highly recommended.     

Seasonal variations of carbohydrates in Pueraria lobata related to growth and phenology

The seasonal changes of non‐structural carbohydrates (NSCs), water‐soluble carbohydrates (WSCs) and starch concentrations were examined in Pueraria lobata throughout its life cycle in order to elucidate the potential points in the seasonal growth and phenological cycles for its improved control. The study was carried out at two different habitat zones with distinct soil conditions in the riparian zone of the Tama River, Tokyo, Japan. One zone, with sandy soil, had lower levels of available nitrogen and phosphorous, while the second zone contained high levels of organic matter and nutrients. The highest and lowest concentrations of the NSC pools in the roots of P. lobata were observed in December and August, respectively, at both study sites. The lowest NSC reserves were attained at the end of the vegetative stage, with the highest NSC reserves found at the end of the reproductive stage. The WSCs gradually decreased from April to August in the roots and then increased until February. The starch concentrations of all the plant organs followed the same pattern as for the WSCs. The stems and leaves did not show the same pattern as did the roots. The total carbohydrate concentrations and pools did not show significant variation between the two sites, suggesting that the soil conditions had very little effect on carbohydrate production in the different organs of the plant. The study suggests that to control P. lobata effectively, the above‐ground biomass should be removed at any date between the end of August and early September.     

Antibacterial activity of oxytetracycline on microbial ecology of Nile tilapia (Oreochromis niloticus) gastrointestinal tract under laboratory condition

The antibacterial effect of oxytetracycline (OTC) on bacterial load, pathogen and possible development of antibiotic resistance in intestinal flora of apparently healthy Nile tilapia (Oreochromis niloticus) was investigated under laboratory condition. OTC, a broad spectrum approved antibiotic widely used in aquaculture, was fed to Nile tilapia through medicated diet at a rate of 2 g/ kg of feed for consecutive 7 days in treatment 1 (T₁) and 30 days in treatment 2 (T₂). Changes in physico‐chemical parameters of water were also recorded where pH and dissolved oxygen influenced bacterial load and coliform count respectively. At the start of the experiment, initial bacterial load in fish intestine was 1.61 ± 2.25 × 10¹⁰ cfu/g, which after OTC treatment decreased significantly (p < .05) to 3.06 ± 2.08 × 10⁸ cfu/g on day 7 and 3.45 ± 4.46 × 10⁷ cfu/g on day 30 when compared with the control group. Among the 10 bacterial genera identified in the intestine, 4 potential public health concern bacteria viz., Salmonella, Escherichia, Enterobacter and Staphylococcaus were predominant. There was a sharp increase in bacterial load on day 18 in T₂ that may be attributed to the development of antibiotic resistance in intestinal bacteria. Antibiotic susceptibility test for isolates against seven antibiotics: amoxycillin, ciprofloxacin, co‐trimoxazole, erythromycin, gentamicin, nitrofurantoin and tetracycline using disc diffusion method revealed significantly increased resistance of Gram‐negative rods (p < .05) that possibly caused increased frequency of OTC‐resistant microorganisms. In conclusion, short‐ and long‐term exposure to OTC treatment affected the distribution of bacterial genera including pathogens in the Nile tilapia gastrointestinal tract and concomitantly influenced their antimicrobial resistance.     

POTASSIUM-CONSTRAINED HIGH YIELDS IN IRRIGATED RICE

Nutritional constraints often restrict yields of field crops in farmers’ fields. Determination of cut-off yield would increase the understanding of yield-limiting nutrients. The present study aimed to determine minimum rice yield target of high-yielding subpopulation in farmers’ fields and to identify the most limiting nutrient in farmers’ fields. Popular high yielding rice was grown in 42 farmers’ fields with two treatments – farmers’ nutrient management plan (FP) and improved nutrient management plan (INM). Nutrient composition was determined from Y-leaf after 45– 50 days of transplanting. Yield cutoff value was determined from compositional nutrient diagnosis (CND) generic model. The CND generic model gave 6.90 Mg ha^?1 as minimum cutoff yield of the high-yield subpopulation. Potassium (K) was identified as the main yield limiting nutrient for rice in piedmont soils. Rice in farmers’ fields may require higher K fertilizer dose for better yield.     

Analysis of lodging parameters in aromatic rice

The research work was conducted with 10 rice germplasm during T. Aman (wet season), 2004, at Bangladesh Rice Research Institute, Gazipur, to assess the different lodging concerned parameters and their interrelationships. A great extent of diversity among aromatic rice genotypes was observed in respect to canopy architecture and lodging related characters. Minimum seedling height was 30 cm for BR39 and the maximum was 47 cm for Hatisail. Variations were found in the cultivars regarding penultimate and flag leaf angles and dimensions of both the leaves. Maximum plant height was recorded to be 153 cm in Baoi jhak and the minimum was 100 cm in BR28. The longest panicle was observed in Nizersail (27 cm) and shortest in Hatisail (21 cm). The range of culm diameter was 4.0–4.7 mm and culm thickness was 0.40–0.51 mm. Rice cultivars varied for bending moment from 812 g · cm (BR28) to 2263 g · cm (Doiar guro). Lodging index was at a minimum 2.7 in BR28 and a maximum 11.28 in Sugandha-1. Plant height exhibited positive correlation with panicle exertion and internode lengths, and hence lodging index. Lodging index was found to have a negative relationship with breaking strength. In path analysis, bending moment projected highest positive direct effect on lodging index.     

ANTIVIRAL EFFECTS OF BACTERIOCIN AGAINST ANIMAL-TO-HUMAN TRANSMITTABLE MUTATED SARS-COV-2: A SYSTEMATIC REVIEW

• Identification of bacteriocin sources• Classification of bacteriocins• Antiviral pathways of bacteriocinsThe COVID-19 infections caused by SARS-CoV-2 have resulted in millions of people being infected and thousands of deaths globally since November 2019. To date, no unique therapeutic agent has been developed to slow the progression of this pandemic. Despite possessing antiviral traits the potential of bacteriocins to combat SARS-CoV-2 infection has not been fully investigated. This review summarizes the mechanisms by which bacteriocins can be manipulated and implemented as effective virus entry blockers with infection suppression potential properties to highly transmissible viruses through comprehensive immune modulations that are potentially effective against COVID-19. These antimicrobial peptides have been suggested as effective antiviral therapeutics and therapeutic supplements to prevent rapid virus transmission. This review also provides a new insight into the cellular and molecular alterations which have made SARS-CoV-2 self-modified with diversified infection patterns. In addition, the possible applications of antimicrobial peptides through both natural and induced mechanisms in infection prevention perspectives on changeable virulence cases are comprehensively analyzed. Specific attention is given to the antiviral mechanisms of the molecules along with their integrative use with synthetic biology and nanosensor technology for rapid detection. Novel bacteriocin based therapeutics with cutting-edge technologies might be potential substitutes for existing time-consuming and expensive approaches to fight this newly emerged global threat.     

Genetic variability in flooding tolerance of mungbean (Vigna radiata L. Wilczek) genotypes

The study was an exploratory in nature conducted using a large number of mungbean (Vigna radiata L. Wilczek) genotypes of diverse growth habit and adaptive characters. Soil flooding induced changes in eleven morpho-physiological characters of one-week old seedlings of 530 mungbean genotypes was compared in the study. The first and second principal components (PC) of principal component analysis (PCA) results accounted for 58 and 14%, respectively of the total variations of mungbean genotypes. The variation for first PC was composed mainly of relative dry weight (DW) of shoot and leaf as well as total DW. The second PC distinguished the genotypes that produced larger root system. There were seven clusters distinguished in the cluster analysis. The genotypes in cluster 4 and 6 performed better in respect of relative total DW and relative root DW, respectively and hence having flooding tolerance. The genotypes in clusters 7 and 1 performed very poorly and those of under clusters 3, 2 and 5 were moderate to poor. D² analysis indicated that the clusters differed significantly from each other. Discriminant function analysis (DFA) reaffirmed that more than 90% of the genotypes were correctly assigned to clusters. Both PCA and DFA confirmed that the relative total DW followed by shoot and leaf DW as well as leaf area were the major discriminatory variables and the root : shoot ratio and root DW were the secondary important variables to distinguish genotypes into groups. In this study, multivariate analyses were used in identifying the mungbean genotypes of desirable traits for flooding tolerance.     

Two new antioxidant bergenin derivatives from the stem of Rivea hypocrateriformis

Two new bergenin derivatives, named rivebergenin A and B (1, and 2), together with two known compounds, bergenin (3) and norbergenin (4) were isolated from the stem of Rivea hypocrateriformis (Desr.) Choisy. The structures of the new compound have been assigned from ¹H and ¹³C NMR spectra, DEPT, and by 2D COSY, HMQC, and HMBC experiments. Compounds 1-4 showed the strong antioxidant activity.     

Zinc and Boron Application at Different Phenological Stages Alleviates Tree Growth,Fruit Yield and Quality of Sweet Orange Cv. ‘Blood Red’

The deficiency of micronutrients, particularly zinc (Zn) and boron (B) has affected vegetative growth, yield and fruit quality of sweet orange in many citrus growing areas of Pakistan. The present study was conducted in 2015 and 2016 to determine the impact of Zn and B supplementation on growth and quality of sweet orange cv. ‘Blood red’. Pre-harvest foliar application of variant Zn and B levels was done at different phenological stages of fruit growth and development, i.e., full bloom, fruit set and premature stage. Results have concluded that pre-harvest foliar application of Zn and B augmented phosphorous, Zn, B, potassium, iron, and manganese contents in leaves, particularly Zn and B content from deficient to optimal level. Moreover, the combined application of Zn and B has also significantly enhanced vegetative characters such as tree height and spread along with reproductive characters, i.e., incremented numbers of fruit, fruit weight, total soluble solids, titratable acidity and ascorbic acid contents. However, among stage comparison, outcomes depicted that foliar application of Zn and B at full bloom?+?fruit set?+?premature stage resulted in maximum production with high quality fruits.