Background: Blackgram [Vigna mungo (L.) Hepper] has significant agronomic and nutritional significance. Its productivity is insufficient to fulfil the expanding local demand in India. Increasing its productivity using appropriate agronomic practices is crucial. With this background, an experiment was conducted to study the effect of foliar application of liquid organic bio-stimulants on development, production and physiological characteristics of blackgram under irrigated conditions. Methods: Seven treatments comprising recommended dose of fertilizers (RDF) with foliar spray of dhasagavya, liquid rhizobium, fish amino acid, panchagavya, PPFM and seaweed extract at 1% and 3%, respectively were tested in randomised block design with three replications. The dimension of blackgram quantitative characters, viz., grain yield, plant height, number of branches per plant, dry matter production (DMP), leaf area index (LAI), number of pods per plant, number of seeds per pod, pod weight per plant, pod length, crop growth rate, total chlorophyll content, soluble protein content and nitrate reductase activity were reduced using principal component analysis (PCA). Result: The PCA was performed on all the attributes as correlation between the quantitative characters was found to be stronger among most of the biometric observations. It was noticed that almost 67% of the data’s total variability, as reflected by the first two principal components. It demonstrated that grain production, DMP, nitrate reductase activity, pods per plant and leaf area index were the primary contributors.

Background: The productivity of blackgram is not adequate to meet the domestic demand of the growing Indian population. Consequently, there is an urgent need for enhancement of productivity through proper management practices. With this background, a research experiment was conducted to investigate the effect of liquid rhizobium with organic bio-stimulants on physiological and biochemical characters, antioxidant enzymes and yield of blackgram. Methods: A field experiment was laid out in randomized block design with three replications during 2021 (Kharif and Rabi) season. The treatments include 100% recommended dose of NPK along with foliar application of dasagavya, liquid rhizobium, fish amino acid, panchagavya, pink pigmented facultative methylotrophs (PPFM) and Sea weed extract with different concentration (1% and 3%, respectively) in addition to control. Organic bio stimulants were sprayed at 30 and 45 days after the sowing of blackgram. Result: The experiment results revealed that the application of 100% RDF+Liquid Rhizobium @ 1% registered maximum physiological and biochemical characters viz., CGR, total chlorophyll content, soluble protein content, nitrate reductase activity, catalase activity, peroxidase activity and number of root nodules plant-1, yield attributes viz., number of pods plant-1, number of seeds pod-1, grain yield (kg ha-1), haulm yield (kg ha-1). Correlation and Regression analysis also indicated that the yield attributes had a positive impact on the grain yield.

Split plot design experiments were conducted to assess the performance of growth regulating compounds for mitigating moisture stress and the incidence of Brown Plant Hopper (BPH) in rice. The main plot treatments (4) comprised moisture stress free control (M₁), moisture stress during panicle initiation stage alone (M₂), moisture stress during flowering stage alone (M₃), and moisture stress during both panicle initiation and flowering stages (M₄). The sub-plot treatments (5) were foliar application of growth regulating compounds including chlormequat chloride at 200 ppm (S₁), mepiquat chloride at 200 ppm (S₂), brassinolide at 0.1 ppm (S₃), pink pigmented facultative methylotrophs (PPFM) at 1% (S₄), and no spray control (S₅). The reduced plant growth attributes were registered under moisture stress at both panicle initiation and flowering stages. The spraying of 1% PPFM during the flowering or both at panicle initiation and flowering stages led to better performance than the other treatments. Also, spraying 1% PPFM brought down the population of BPH to a considerable level during both years of experiments. This suggests that spraying 1% PPFM in the post-flowering stage helps to mitigate the ill effect the moisture stress and BPH incidence.

Using chemical defoliants to remove cotton leaves represents a groundbreaking shift in cotton cultivation. The mechanization of cotton harvest is increasing, but a substantial amount of foliage that remains on the plant even at maturity is the major barrier for mechanical harvest. Properly completing mechanical and manual harvests requires artificial leaf detachment through defoliants. Still there is no proper defoliant concentration, application times and mechanism of action available. Therefore, the present study aimed to find an effective defoliant and application time to enhance mechanical harvest efficiency, along with a clear description of the mechanism of actions in cotton CO17 (Gossypium hirsutum). The field experiment was conducted during the year 2019-20 and used five concentrations of Thidiazuron defoliant (100, 150, 200, 250 and 300ppm) and Ethephon@0.5% (T2) in cotton variety CO17 to study the physiological, biochemical and hormonal responses at 120, 127 and 134 days after sowing. As a result, the concentrations of plant growth hormones, indole-3 acetic acid (4.9 fold), zeatin (32.7%) and gibberellic acid (7 fold) reduced. In contrast, abscisic acid (48.6%), jasmonic acid (34.9%), salicylic acid (2.15 fold) increased in the T7- Thidiazuron + Diuron (300 ppm) treatment followed by T5-Thidiazuron + Diuron (200 ppm). Additionally, the antioxidant enzymes ascorbate peroxidase, peroxidase, catalase, superoxide dismutase, cellulase in leaves, petiole and bolls were decreased due to defoliant T5- Thidiazuron + Diuron (200 ppm) followed by T7-Thidiazuron + Diuron (300 ppm), indicating that the hormone concentration, antioxidative and hydrolytic enzymes are ruled out and forces the defoliation process.

Cotton is one of the most important cash crop grown for its fibre, which is the raw material for the textile industry. In India, the average yield and profitability of cotton cultivation are low as compared to developing countries. The main reason for this is hand picking of bolls, which is labour intensive resulting into low income of cotton growers. Furthermore, in India, most of the cotton varieties are indeterminate where the bolls do not mature at the same time and thus requires repeated hand pickings. Whereas the developed countries have 100% mechanized cotton picking due to determinate or semi-determinate plant types. Adoption of mechanical harvesting in India is dependent upon the availability of suitable cotton varieties as well as defoliants, desiccants, boll openers, growth hormones and re-growth inhibitors (Thatikunta et al., 2018). Defoliation before cotton harvesting is very important to maintain the quality of produce. In this paper, a comprehensive review is presented on effect and timing of application of defoliants on physiological characteristics of cotton. This will help in developing further research proposals to develop plant types for mechanical harvesting and use of defoliates to produce good fiber quality and increased farm income.