Crop yield data are critical for managing agricultural sustainability and assessing national food security. This study aims at increasing peanut productivity from its current levels by analyzing the yield gap (difference) of potential production between theoretical yield and actual farmers’ yields. The spatial yield gap of peanut for the Tiruvannamalai district of Tamil Nadu is examined in this investigation by integrating the products of microwave remote sensing (SAR Sentinel-1A) with the DSSAT CROPGRO Peanut simulation model. The CROPGRO (crop growth) Peanut model was calibrated and validated by conducting a field experiment at Oilseeds Research Station, Tindivanam during Rabi (spring) 2019 for predominant cultivars, i.e., TMV 7, TMV 13, VRI 2 and G 7. Actual attainable yield was recorded by organizing crop cutting experiments (CCEs) with the help of the Department of Agriculture Economics and Statistics in the respective monitoring villages. The regression analysis between the maximum recorded DSSAT leaf area index (LAI) at the peak flowering stage of peanut and the yield recorded by CCEs for the spatial yield estimation of peanut in the Tiruvannamalai district of Tamil Nadu during Rabi 2021 was carried out using ArcGIS 10.6 software. The DSSAT CROPGRO simulated potential yield ranged from 3194 to 4843 kg/ha, whereas actual yield ranged from 1228 to 3106 kg/ha, with a considerable disparity between the actual and potential yield levels (from 1217 to 2346 kg/ha) of the monitored locations. The minimum, maximum and average yield gaps in peanut for Tiruvannamalai district were assessed as 1890, 2324 and 2134 kg/ha, respectively. In order to reduce the production difference of peanut cultivation, farmers should focus more on management issues such as time of sowing, irrigation or water management, quantity and sources of nutrients, cultivar selection and availability of quality seeds tailored to each region.

As a renewable resource, seaweeds are abundant in secondary metabolites that have the potential to accelerate metabolic processes in insects, induce toxicity, alter growth and development and delay oviposition and feeding activities. The purpose of the current experiment was to examine the insecticidal activity of brown and red algal seaweeds against diamondback moth under laboratory conditions in Agricultural College and Research Institute, Madurai. The marine algae were collected from Ramanathapuram districts of Tamil Nadu. Different extracts of seaweeds were made using the Soxhlet extraction method and were tested for toxicity at various concentrations, including 1%, 2% and 3% against a homogenous culture of second-instar P. xylostella larvae. Their effects were compared to those of solvents (Methanol, chloroform, hexane and acetone), a treated check (Azadirachtin 1% @ 2ml/l) and an untreated control under leaf dip bioassay with three replications in Completely Randomized Design. The larval mortality data on the treated larvae were collected systematically, statistically examined and reported. Among different concentrations of tested seaweed extracts, the highest larvicidal activity (83.33%) was observed after 72 hrs with Sargassum wightii methanolic extracts @ 3% concentration and the least larval mortality was observed for Gracilaria edulis acetone extracts @ 1% concentration (23.33%). Phytochemical profiling of all methanolic extracts of seaweeds was done by GC-MS/MS analysis. The heat map of the metabolites identified nine metabolites (6-Octadecanoic acid, Papveroline, Paroxypropione, o-Methoxymandelic acid, 11, 14-Eicosadienoic acid, Oxirane, 2-Hydroxy-5-Methyl acetophenone, Alpha-Bromo-gamma-valerolactone, 2-O-Methlyl-d-xylose) in S.wightii with high intensity that were not detected in other species. These metabolites are likely to possess insecticidal property. This study suggests the use of seaweed extract as botanical pesticide which will be an alternative in the creation of an Integrated Pest Management (IPM) module for the control of diamondback moths.

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Pink stem borer Sesamia inferens causes deadheart and white ear symptoms by boring into stem and peduncle region causing yield losses in barnyard millet. A field trial to find out efficacy of cartap hydrochloride 4G, chlorantraniliprole 18.5SC, flubendiamide 20WG, emamectin benzoate 5SG, spinetoram 11.7SC and phorate 10G against S. inferens was carried out in Tamil Nadu. Spinetoram 11.7SC (92.63%) was the most effective followed by flubendiamide 20WG (90.56%). Phorate 10G (81.57%) was found to be less effective. Plots treated with spinetoram 11.7SC gave maximum yield (9.57 q/ ha) with the cost benefit ratio of 1:3.08 followed by flubendiamide 20% WG (8.91 q/ ha) with the cost benefit ratio of 1:3.42. Phorate 10 G was the least performing treatment with 29.62% increase in yield over control with the cost benefit ratio of 1:2.84. Control plot recorded 44.5% less yield when compared to treated plots.

Rice (Oryza sativa L.) grain yield is reduced by drought stress during reproductive stages. In this work, the effects of foliar selenium (Se) spray on the reduction of drought stress are measured and the most critical stage of rice is identified. Three field experiments were carried out. In experiments I and II, the sensitive stage was determined by imposing drought stress at the panicle initiation and flowering stages by withholding irrigation for 10, 15, 20, and 25 days. In experiment III, drought stress was induced by depriving plants of moisture for 20 or 25 days. Se spray was then applied at rates of 0, 10, and 20 mg L−1 to alleviate the drought, and its effects were evaluated. Overall, it was reported that the panicle initiation stage was more vulnerable to drought stress than the flowering stage, as evidenced by a larger reduction in grain yield. Employing Se as a foliar spray at a rate of 20 mg L−1 under drought stress enhanced the number of filled grains m−2, the total number of grains m−2, and grain yield ha−1 by 22.0, 4.3, and 11.0%, respectively, over water spray. This shows a positive interaction or synergistic interaction between drought tolerance and selenium application. These results demonstrate that foliage supplementation of Se at a dosage of 20 mg L−1 alleviate the adverse effects of drought stress at the panicle initiation stage in rice cultivation. Se mitigated the negative effects of drought by improving the membrane stability index, relative water content, and proline content.