A split plot design field study was conducted during summer month of 2012 and 2013 at the vegetable block of Indian Institute of Horticultural Research in Bangalore, India to evaluate if priming could improve grain yield and water use efficiency of cowpea under limited water supply condition through drip system. Seeds of cultivar Arka garima received the following priming treatments: they were soaked in GA 3 ,Calcium Chloride, Ammonium Molybdate, Potassium Bromide, Magnesium Nitrate, Zinc Sulphate solutions, and aerated distil water (hydropriming) for 24 hours at 15 o C. Crops were subjected to three irrigation intervals in which the irrigation was applied at 0.9, 0.7, 0.5 Epan Replenishment of evaporation. Seed priming treatments reduced the mean emergence time, promoted germination, early canopy development and flower initiation in comparison to the untreated control. Plant height, number of branches, total dry matter accumulation, number of pods per plant, number of seeds per pod, 1000 seed weight and grain and biological yield, harvest index and irrigation water use efficiency increased by different priming treatments. Seed priming increased the irrigation water use efficiency (IWUE) of all irrigation regimes. Grain yields linearly increased at 0.9 Epan Replenishment while maximum IWUE was achieved at 0.5 Epan Replenishment. Results suggest that the use of seed priming with either GA 3 (100ppm) or Ammonium Molybdate (10 -3 M) for 24 hours at low concentration can be helpful in cowpea under both optimum as well as limited water conditions.
Introduction Capsicum grown in low-cost polyhouses (a protective shade made up of polythene used for growing high-value agricultural products) is often infested by thrips and acephate is an insecticide, which is frequently and repeatedly used for controlling this pest. Objectives Since a polyhouse microclimate is different from that of an open field, a study was carried out to compare the decline pattern of acephate residues in capsicum grown in polyhouse to that grown in open field. Methods Laboratory standardized methodologies using gas liquid chromatography was adopted to estimate residues of acephate and its metabolite, methamidophos in capsicum fruits. Results and Conclusion Higher initial residues (0.39 ppm) and persistence of acephate (pre-harvest interval = 16 days) and its methamidophos metabolite was detected in capsicum grown in polyhouse as compared to that grown in open field (pre-harvest interval = 12 days) in spite of higher rate of growth and consequent residue 'dilution' in polyhousegrown capsicum.
This investigation was undertaken to compare the dissipation pattern of flubendiamide in capsicum fruits under poly-house and open field after giving spray applications at the recommended and double doses of 48 g a.i. ha(-1) and 96 g a.i. ha(-1). Extraction and purification of capsicum fruit samples were carried out by the QuEChERS method. Residues of flubendiamide and its metabolite, des-iodo flubendiamide, were analyzed by high-performance liquid chromatography-photodiode array, and confirmed by liquid chromatography-mass spectrometry/mass spectrometry. Limit of quantification of the method was 0.05 mg kg(-1), and recovery of the insecticides was in the range of 89.6-104.3%, with relative standard deviation being 4.5-11.5%. The measurement uncertainty of the analytical method was in the range of 10.7-15.7%. Initial residue deposits of flubendiamide on capsicum fruits grown under poly-house conditions were (0.977 and 1.834 mg kg(-1)) higher than that grown in the field (0.665 and 1.545 mg kg(-1)). Flubendiamide residues persisted for 15 days in field-grown and for 25 days in poly-house-grown capsicum fruits. The residues were degraded with the half-lives of 4.3-4.7 and 5.6-6.6 days in field and poly-house respectively. Des-iodo flubendiamide was not detected in capsicum fruits or soil. The residues of flubendiamide degraded to below the maximum residue limit notified by Codex Alimentarius Commission (FAO/WHO) after 1 and 6 days in open field, and 3 and 10 days in poly-house. The results of the study indicated that flubendiamide applied to capsicum under controlled environmental conditions required longer pre-harvest interval to allow its residues to dissipate to the safe level.
Dissipation of spiromesifen and its metabolite, spiromesifen-enol, on tomato fruit, tomato leaf, and soil was studied in the open field and controlled environmental conditions. Sample preparation was carried out by QuEChERS method and analysis using LC-MS/MS. Method validation for analysis of the compounds was carried out as per "single laboratory method validation guidelines." Method validation studies gave satisfactory recoveries for spiromesifen and spiromesifen-enol (71.59-105.3%) with relative standard deviation (RSD) < 20%. LOD and LOQ of the method were 0.0015 μg mL and 0.005 mg kg, respectively. Spiromesifen residues on tomato fruits were 0.855 and 1.545 mg kg in open field and 0.976 and 1.670 mg kg under polyhouse condition, from treatments at the standard and double doses of 125 and 250 g a.i. ha, respectively. On tomato leaves, the residues were 5.64 and 8.226 mg kg in open field and 6.874 and 10.187 mg kg in the polyhouse. In soil, the residues were 0.532 and 1.032 mg kg and 0.486 and 0.925 mg kg under open field and polyhouse conditions, respectively. The half-life of degradation of spiromesifen on tomato fruit was 6-6.5 days in the open field and 8.1-9.3 days in the polyhouse. On tomato leaves, it was 7-7.6 and 17.6-18.4 days and in soil 5.6-7.4 and 8.4-9.5 days, respectively. Metabolite, spiromesifen-enol, was not detected in any of the sample throughout the study period. Photodegradation could be the major route for dissipation of spiromesifen in the tomato leaves, whereas in the fruits, it may be the combination of photodegradation and dilution due to fruit growth. The results of the study can be utilized for application of spiromesifen in plant protection of tomato crop under protected environmental conditions.
A field study was conducted during summer season of 2012 and 2013 at Indian Institute of Horticultural Research in Bangalore, India to evaluate if priming could improve grain yield and water use efficiency of cowpea under limited water supply condition through drip system. Seed variety Arka Garima received the following priming treatments: they were soaked in GA 3 ,CaCl 2 , ammonium molybdate, KBr, MgNO 3 , ZnSO 4 solutions and water (hydropriming) for 24 hours at 15 o C. Crop was subjected to three irrigation intervals in which the irrigation was applied at 0.9, 0.7, 0.5 Epan Replenishment of evaporation. Plant height, number of trifoliate leaves, total dry matter accumulation, number of pods per plant, number of seeds per pod, 1000 seed weight and grain and biological yield were increased by different priming treatments compared to control. Seed priming increased the LAI, RGR, CGR and NAR at all irrigation regimes. Results suggest that the use of seed priming with either GA 3 (100ppm) or ammonium molybdate (10 -3 M) for 24 hours at low concentration can be helpful in cowpea under both optimum as well as limited water conditions.
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