1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
Permanent URI for this communityhttp://localhost:4000/handle/123456789/1
Browse
39 results
Search Results
Item Standardisation of operational procedures for pro-tray seedling production of vegetables(Department of Vegetable Science, College of Agriculture , Vellanikkara, 2022-01-29) Arya, S; Dicto Jose ,MHealthy seedlings are the most important prerequisite for any vegetable crop to reach its full output potential. As a result, large-scale seedling production is becoming a profession and a commercial activity. Farmers used to generate seedlings at a reasonable cost in nursery beds in the past. However, due to some drawbacks like poor germination, higher pest and disease incidence, poor field establishment etc. in traditional nurseries, many progressive farmers and agriculture entrepreneurs have turned their attention to the commercial production of quality seedlings utilising seedling trays or pro-trays. In this background, the present study entitled ‘Standardisation of operational procedures for pro-tray seedling production of vegetables’ was undertaken with the objective of standardising best growing media, pre-sowing seed invigoration, and evaluating the effect of biofertilizer on pro-tray seedling production of vegetables. The present study was carried out at the Department of Vegetable Science, College of Agriculture, Vellanikkara as three experiments during 2020-21. All three experiments were conducted in a Completely Randomized Design with three replications. In the first experiment seeds of tomato var. Anagha, chilli var. Anugraha, cucumber var. Heera, and okra var. Salkeerthi collected from the Department of Vegetable Science were sown in seventeen different media that were initially analysed for various physicochemical properties. The growth parameters of the seedlings raised in the poly house were assessed at the stage of commercial sale of each crop i.e., 15 days after sowing (DAS) in cucumber and okra and 30 DAS in chilli and tomato. The results showed that T13 (cocopeat: vermiculite: perlite - 1:1:1) and T17 recorded comparatively minimum bulk density, maximum water holding capacity and porosity which are desirable physical properties for good seedling growth. T17 (coir pith compost: vermiculite: perlite - 3:1:1) was found to be the best soil-less media for all four crops based on growth parameters and cost analysis. Among soil containing media T6 having soil and dried powdered cow dung in equal proportion and T10 having soil, cocopeat and dried cow dung exhibited a higher benefit cost ratio and was found to be on par with T17 for most of the growth parameters. Farmers do not have easy access to vermiculite and perlite, and they are costly. In this context, soil, cocopeat and dried powdered cow dung in equal proportion is found to be an alternate media comprising locally available inputs and affordable by the farmers. The best media from the first experiment was chosen for further trials. The second trial comprised of nine different seed treatments including various concentrations of KNO3 and Pseudomonas. Pre-sowing seed invigoration with 0.5% KNO3 in combination with 1% Pseudomonas was found to be highly effective in improving germination and growth parameters viz., germination percentage, plant height, root length, vigour index Ⅰ & Ⅱ and chlorophyll content of seedlings of tomato, chilli, cucumber and okra. This combination has the dual advantage of providing potassium and nitrogen to the seedlings and imparting resistance from diseases especially damping off. So, these treatments can be effectively utilized for producing healthy and vigorous vegetable seedlings. The third experiment included nine treatments in which different biofertilizers viz., PGPR Mix-1, Pseudomonas fluorescense, Trichoderma asperellum and arbuscular mycorrhizal fungi were inoculated in the media individually and in combination. Evaluation of the effect of biofertilizers showed that higher growth parameters like plant height, root length, leaf area, collar girth, vigour index Ⅰ and vigour index Ⅱ are comparatively higher in the treatment containing PGPR, AMF and along with either Pseudomonas or Trichoderma. In the above three experiments the best treatments were identified by ranking based on an index derived from principal component analysis. The characters viz., number of leaves, leaf area, collar girth, vigour index Ⅰ & Ⅱ and total chlorophyll content was used for performing PCA. The loadings of principal component having Eigen value more than one was taken as weightage. Using weightage, an index was derived and the treatments having higher index was ranked higher. The best media obtained include cocopeat: vermiculite: perlite (3:1:1) and soil: cocopeat: cow dung (1:1:1). A combination of 0.5% KNO3 and 1% Pseudomonas was the best seed invigoration treatment. Among different biofertilizers evaluated the combination of AMF, PGPR Mix-1 and Pseudomonas was found to be the best. Based on the insights of the above three trials, standard operational protocol for seedling production of tomato, chilli, cucumber and okra is generated for use by farmersItem Entomopathogenic nematode for the management of cucumber moth, Diaphania indica (Saunders) (Lepidoptera: Crambidae) in bitter gourd(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2023-04-12) Gayathri, P S; Nisha, M SThe research work entitled “Entomopathogenic nematode for the management of cucumber moth, Diaphania indica (Saunders) (Lepidoptera: Crambidae) in bitter gourd” was carried out at Department of Entomology, College of Agriculture, Vellayani during 2020 to 2022. The objectives were to test the pathogenicity of entomopathogenic nematodes (EPNs) and to evaluate the effective EPN formulation against cucumber moth, D. indica in bitter gourd. The pathogenicity of two strains of entomopathogenic nematodes viz. Heterorhabditis indica Poinar and Steinernema carpocapsae Weiser were assessed against 3rd instar larvae of D. indica and Henosepilachna septima Dieke. Three different formulations viz. sponge, talc and alginate gel of the effective EPN strain were prepared and stored up to 11 weeks. Then, the survival percentage and virulence of infective juveniles (IJs) in each formulation was evaluated. A pot culture study was also conducted to evaluate the pathogenicity of effective EPN formulation against D. indica in bitter gourd. In the pathogenicity test, H. indica @ 100 IJs recorded highest mortality percentage of 42.50 for D. indica and 40.00 for H. septima at 24 Hours After Treatment (HAT). No mortality was observed for S. carpocapsae at all the concentration levels (10, 20, 50 and 100 IJs) for D. indica at 24 HAT. At 48 HAT, hundred per cent mortality was recorded only for H. indica at 100 IJs and it was on par with H. indica at 50 IJs. Both H. indica and S. carpocapsae at 50 and 100 IJs showed hundred per cent mortality at 60 HAT. All treatments showed hundred per cent mortality at 72 HAT. The number of IJs emerged from cadavers were slightly more for H. indica than S. carpocapsae for the same concentration of IJs. From the 1st experiment, H. indica was found to be more effective than S. carpocapsae against D. indica and H. septima. Therefore, survival percentage of IJs of H. indica were evaluated in different formulations. Highest survival percentage (100 per cent) was observed in alginate gel formulation in 1st week and it was on par with talc formulation up to 2 weeks. More than 50% survival of IJs was observed upto 8 weeks in alginate gel, 6 weeks in talc, 5 weeks in sponges and 3 weeks in water. 112 Results on virulence of IJs in different formulations revealed that IJs from alginate gel recorded mortality percentage ranging from 32.50 to 100.00 and 0.00 to 23.33 in 1st and 11th week of storage respectively against D. indica. It was statistically on par with freshly harvested juveniles at 72 HAT up to 5th week of storage. The next best formulation was found to be talc which was on par with freshly harvested juveniles at 72 HAT up to 4th week of storage. In the pot culture study, it was observed that the mortality of D. indica caused by IJs from alginate gel-based formulation of H. indica @ 4g L-1 (42.22 and 68.88) and talc- based formulation of H. indica @ 20g L-1 (40.00 and 68.88) was superior to talc-based formulation of Beauveria bassiana @ 2% (26.66 and 62.22) and neemazal 1% @ 0.2% + tween 80 (1%) (17.77 and 42.22) at 1 and 3 DAT respectively. The effect of H. indica was on par with talc-based formulation of B. bassiana @ 2% and neemazal 1% @ 0.2% + tween 80 (1%) at 5 and 7 DAT. At the same time, the highest mortality (100 per cent) was obtained for chlorantraniliprole 18.5SC@ 30g a.i. ha-1. The damage caused by D. indica ranged from 16.92 to 34.99 in alginate gel-based formulation of H. indica @ 4g L-1 and 19.97 to 41.74 in talc- based formulation of H. indica @ 20g L-1. Its effect on damage of leaves was on par with talc-based formulation of B. bassiana @ 2% of damage percentage 28.57, 40.21 and 41.00 at 3, 5, and 7 DAT respectively. Effect of H. indica formulations on the emergence of Bactrocera cucurbitae (Coquillett) from soil was studied under in vitro. Soil treated with alginate gel-based formulation of H. indica @ 4g L-1 and talc- based formulation of H. indica @ 20g L-1 recorded 16.66 per cent emergence of B. cucurbitae and its effect was on par with chlorantraniliprole 18.5SC@ 30g a.i. ha-1. Based on the present study, it can be concluded that H. indica can be stored in formulations viz. alginate gel and talc for better shelf life and it can be used as a biocontrol agent against D. indica, H. septima and B. cucurbitae in bitter gourd.Item Behavioural response of cucumber moth Diaphania indica (Saunders) (Lepidoptera:Pyralidae) towards select host plant extracts(Department of Entomology, College of Agriculture,Vellayani, 2024-02-09) Geethu Gopakumar.; Vijayasree, VAn investigation entitled “Behavioural response of cucumber moth Diaphania indica (Saunders) (Lepidoptera: Pyralidae) towards select host plant extracts” was conducted at the Department of Entomology, College of Agriculture, Vellayani during 2021-2023 with an objective to evaluate plant extracts and synthetic volatiles for the behavioural and electrophysiological responses of D. indica and identify the components of the plant extract. The plants evaluated in the study were Momordica charantia L, Trichosanthus anguina L., Cucumis sativus L., Coccinia grandis (L.) Voigt (wild and cultivated type), Cucumis melo var. acidulus Naudin., Solanum melongena L. and Amaranthus tricolor L. The behavioural bioassay of adult D. indica in Y-tube and modified olfactometer using plant extracts did not give any reliable response. The olfactory response of D. indica larvae was highest to C. grandis (wild) with a mean attraction of 23.33% followed by M. charantia, C. grandis and C. sativus with 10.83%, 9.17% and 8.33% attraction, respectively. In the GC-MS analysis of fresh leaf extracts, fatty acid, (Z,Z,Z)- 9,12,15-Octadecatrienoic acid (α-linolenic acid) and n-hexadecanoic acid (palmitic acid) was detected in all plant extracts except C. grandis (wild) and M. charantia, respectively. The alkane, dotriacontane was found in M. charantia, T. anguina, C. grandis (wild), A. tricolor and C. melo var. acidulus. The volatile compound benzaldehyde was identified in all samples except C. grandis (wild) and C. melo var. acidulus in headspace GCMS analysis of dried leaves. Electroantennographic studies showed gravid females are more responsive to plant extracts followed by unmated females. Gravid females showed highest response to extracts of M. charantia (0.25mV) and unmated females to C. sativus extract (0.14 mV). The synthetic volatile compounds, benzaldehyde and benzyl, alcohol when tested alone elicited the highest responses in the crude state. Among different combinations of these compounds, a mixture of 10µL of crude benzaldehyde and 30 µL of crude benzyl alcohol had the highest response (0.210 mV). This was on par with the response values of M. charantia and C. sativus extracts. While evaluating synthetic compounds for behavioural responses, a mixture of plateiiiiiii that D. indica shows a considerable electrophysiological, oviposition and feeding preference for M. charantia and C. sativus compared to other host plants. Linolenic acid, palmitic acid, dotriacontane and benzaldehyde were identified as common components in these plants which have reported kairomonal properties. The kairomonal property of benzaldehyde in combination with benzyl alcohol was proved in this study.Item Standardisation of fertigation schedule for parthenocarpic cucumber (Cucumis sativus L.) hybrid KPCH 1 under polyhouse(Department of Vegetable Science, College of Agriculture,Vellanikkara, 23-03-08) Mintu Hanna, Reji; Dicto Jose, MItem Standardisation of operational procedures for pro-tray seedling production of vegetables(Department of Vegetable Science, College of Agriculture, Vellanikkara, 2022) Arya, S; Dicto Jose, MHealthy seedlings are the most important prerequisite for any vegetable crop to reach its full output potential. As a result, large-scale seedling production is becoming a profession and a commercial activity. Farmers used to generate seedlings at a reasonable cost in nursery beds in the past. However, due to some drawbacks like poor germination, higher pest and disease incidence, poor field establishment etc. in traditional nurseries, many progressive farmers and agriculture entrepreneurs have turned their attention to the commercial production of quality seedlings utilising seedling trays or pro-trays. In this background, the present study entitled ‘Standardisation of operational procedures for pro-tray seedling production of vegetables’ was undertaken with the objective of standardising best growing media, pre-sowing seed invigoration, and evaluating the effect of biofertilizer on pro-tray seedling production of vegetables. The present study was carried out at the Department of Vegetable Science, College of Agriculture, Vellanikkara as three experiments during 2020-21. All three experiments were conducted in a Completely Randomized Design with three replications. In the first experiment seeds of tomato var. Anagha, chilli var. Anugraha, cucumber var. Heera, and okra var. Salkeerthi collected from the Department of Vegetable Science were sown in seventeen different media that were initially analysed for various physicochemical properties. The growth parameters of the seedlings raised in the poly house were assessed at the stage of commercial sale of each crop i.e., 15 days after sowing (DAS) in cucumber and okra and 30 DAS in chilli and tomato. The results showed that T13 (cocopeat: vermiculite: perlite - 1:1:1) and T17 recorded comparatively minimum bulk density, maximum water holding capacity and porosity which are desirable physical properties for good seedling growth. T17 (coir pith compost: vermiculite: perlite - 3:1:1) was found to be the best soil-less media for all four crops based on growth parameters and cost analysis. Among soil containing media T6 having soil and dried powdered cow dung in equal proportion and T10 having soil, cocopeat and dried cow dung exhibited a higher benefit cost ratio and was found to be on par with T17 for most of the growth parameters. Farmers do not have easy access to vermiculite and perlite, and they are costly. In this context, soil, cocopeat and dried powdered cow dung in equal proportion is found to be an alternate media comprising locally available inputs and affordable by the farmers. The best media from the first experiment was chosen for further trials. The second trial comprised of nine different seed treatments including various concentrations of KNO3 and Pseudomonas. Pre-sowing seed invigoration with 0.5% KNO3 in combination with 1% Pseudomonas was found to be highly effective in improving germination and growth parameters viz., germination percentage, plant height, root length, vigour index Ⅰ & Ⅱ and chlorophyll content of seedlings of tomato, chilli, cucumber and okra. This combination has the dual advantage of providing potassium and nitrogen to the seedlings and imparting resistance from diseases especially damping off. So, these treatments can be effectively utilized for producing healthy and vigorous vegetable seedlings. The third experiment included nine treatments in which different biofertilizers viz., PGPR Mix-1, Pseudomonas fluorescense, Trichoderma asperellum and arbuscular mycorrhizal fungi were inoculated in the media individually and in combination. Evaluation of the effect of biofertilizers showed that higher growth parameters like plant height, root length, leaf area, collar girth, vigour index Ⅰ and vigour index Ⅱ are comparatively higher in the treatment containing PGPR, AMF and along with either Pseudomonas or Trichoderma. In the above three experiments the best treatments were identified by ranking based on an index derived from principal component analysis. The characters viz., number of leaves, leaf area, collar girth, vigour index Ⅰ & Ⅱ and total chlorophyll content was used for performing PCA. The loadings of principal component having Eigen value more than one was taken as weightage. Using weightage, an index was derived and the treatments having higher index was ranked higher. The best media obtained include cocopeat: vermiculite: perlite (3:1:1) and soil: cocopeat: cow dung (1:1:1). A combination of 0.5% KNO3 and 1% Pseudomonas was the best seed invigoration treatment. Among different biofertilizers evaluated the combination of AMF, PGPR Mix-1 and Pseudomonas was found to be the best. Based on the insights of the above three trials, standard operational protocol for seedling production of tomato, chilli, cucumber and okra is generated for use by farmers.Item Pollination efficiency of stingless bee tetragonula iridipennis (Smith) in cucumber (Cucumis sativus L.) under protected cultivation(Department of Agricultural Entonology, College of Argiculture, Vellayani, 2020) Lintu, V V; Amritha, V SThe present investigation entitled “Pollination efficiency of stingless bee, Tetragonula iridipennis (Smith) in cucumber (Cucumis sativus L.) under protected cultivation” was conducted in the polyhouse at College of Agriculture, Vellayani from November 2019 to February 2020. The objective was to evaluate the effect of pollination by stingless bee (T. iridipennis) on fruit set, yield and quality of salad cucumber under protected cultivation. The foraging behaviour of T. iridipennis inside the protected environment was observed to evaluate their diurnal variations in resource collection and pollination ability in cucumber flowers. Observations on mode of alighting of bees, foraging behaviour of stingless bees, floral biology of C. sativus and pollination efficiency of stingless bees in terms of the quantitative and qualitative parameters were recorded. Most of the observed bees were side workers (78 %), which landed on the petals and proceeded towards the reproductive part (stamen or stigma) while the rest of the foragers (22 %) were top workers, which landed directly on the top of stamen or stigma. Foraging rate was the highest (6.80 male flowers 5 min-1) during the time of initiation of foraging (0800 – 0900 h), while maximum foraging intensity was recorded as 4.40 bees male flower-1 10 min-1 during 1000 – 1100 h. Maximum time spent by pollen collectors per male flower was recorded as 44.20 sec. during 1200 - 1300 h of the day during which maximum pollen grains were observed from the body of the bees. Irrespective of the time period, stingless bee spent significantly more time on female flowers compared to that of male flowers in respective time intervals. The diurnal activity of a colony assessed in terms of the total number of incoming and outgoing foragers at the hive entrance revealed that their number increased with the ascent of the day, reached a maximum during 1300-1400 h (67.00 and 58.00 number of incoming and outgoing foragers respectively) and then decreased thereafter. Weekly observations showed that the pollen and nectar foraging activity of stingless bees varies in a day with the peak period during 1200-1400 h. A significant positive correlation was recorded between temperature and number of incoming foragers (r = 0.78) while a significant negative correlation was observed between relative humidity and number of incoming foragers (r = -0.68). Studies on the floral biology as well as the morphology of bees has revealed that the individual nectar foraging bee insert its head into the corolla tube of both male and female flowers to reach the nectaries. Significant increase in per cent fruit set was observed in stingless bee pollinated crop (76%) compared to hand pollinated one (54%) whereas the qualitative yield parameters like per cent malformed fruit, length and diameter of fruit were statistically on par. With regard to the quantitative yield parameters significantly higher single fruit weight, number of seeds per fruit and germination per cent (2 DAS) (685.00 g, 344.10 seeds/ fruit and 90.60 %, respectively) was recorded from the stingless bee pollinated crop than that of the control crop (555.00 g, 210.90 seeds/ fruit and 63.00 %, respectively). Higher yield was observed in augmented pollination (5.09 kg m-2) compared to hand pollination (3.16 kg m-2). Apart from this, bee assisted pollination was economically feasible with better B:C ratio (1.23) than that of the hand pollinated one (0.67). The foraging activity of bees varied in a day with the peak period during 1200-1400 h. Stingless bee pollination had a profound influence on the per cent fruit set as well as the quantitative parameters like fruit weight, germination percentage and number of seeds per fruit. Augmentative pollination with stingless bee under protected cultivation resulted in increased yield of 61 per cent in C. sativus.Item Varietal screening of black pepper to cucumber mosaic virus and Piper yellow mottle virus and their sero molecular detection(Department of Plant Pathology, College of Agriculture, Vellayani, 2020) Arya, M; Radhika, N SItem Management of pests of cowpea and salad cucumber in polyhouse(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2016) Thamilarasi, N; Ambily PaulA study on “Management of pests of cowpea and salad cucumber in polyhouse” was undertaken in polyhouses of Thiruvananthapuram district and College of Agriculture, Vellayani during January 2015 to May 2016. The main objectives were to document the pests and natural enemies on cowpea and salad cucumber in polyhouses and to evaluate the efficacy of new generation insecticides against the major pests. A purposive survey was conducted in 20 polyhouses in Thiruvananthapuram district to document the pests and natural enemies. Sucking pests viz., pea aphid, Aphis craccivora (Koch), mealy bug, Ferrisia virgata (Cockerell), pod bug, Riptortus pedestris (Fabricius), fulgorid bug, Eurybrachys tomentosa (Fabricius), thrips, Ayyaria chaetophora (Karny), spotted red mite, Tetranychus truncatus (Ehara) and leaf feeders viz., pod borer, Lampides boeticus (Linnaeus), tobacco caterpillar, Spodoptera litura (Fabricius), leaf beetle Pagria flavopustulata (Baly), American serpentine leaf miner, Liriomyza trifolii (Burgess) are the pests associated with cowpea. New pests viz., tortrycid larvae, leaf miner and girdle beetle, Oberiopsis brevis (Gahan) were reported from cowpea under polyhouse. Sucking pests viz., green peach aphid, Myzus persicae (Sulzer), mealy bug, Ferrisia virgata (Cockerell), thrips, Astrothrips tumiceps (Karny), Thrips hawaiiensis (Morgan), Frankliniella schultzei (Trybom) spotted red mite, Tetranychus sp, and leaf feeders viz., pumpkin caterpillar, Diaphania indica (Saunders), American serpentine leaf miner, Liriomyza trifolii (Burgess) are associated with salad cucumber under polyhouse conditions. The natural enemies observed were coccinellids, syrphids and spiders viz., Oxyopes javanus (Thorell), Oxyopes sunandae (Tikader) and Argiope pulchella (Thorell) from both cowpea and salad cucumber. The data on preliminary survey revealed that both sucking and leaf feeder pests caused significant damage to cowpea and salad cucumber inside polyhouse.Experiments were carried out in CRD to evaluate the efficacy of new generation insecticides viz. acetamiprid 0.10 g L -1 , imidacloprid 0.20 mL L -1 , thiamethoxam 0.30 g L -1 , thiacloprid 0.25 mL L -1 , dimethoate 1.50 mL L -1 against sucking insects viz., A. craccivora, M. persicae and R. pedestris and acaricides viz., spiromesifen 0.80 mL L -1 , fenpyroximate 0.60 mL L -1 , dimethoate 1.50 mL L -1 against Tetranychus sp. Spinosad 0.30 mL L -1 , chlorantraniliprole 0.30 mL L -1 , flubendiamide 0.10 mL L -1 , indoxacarb 1.00 mL L -1 , quinalphos 3.00 mL L -1 were tested against leaf feeders viz., L. trifolii and D. indica. Evaluating the efficacy of new generation insecticides, thiamethoxam 0.30 g L -1 and imidacloprid 0.20 mL L -1 were found to be effective against sucking pests which reduced the mean population of A. craccivora to 7.33 and 12.67 aphids plant -1 respectively and M. persicae to 4.67 and 11.67 aphids plant -1 respectively after 15 days of treatment. However, thiamethoxam 0.30 g L -1 and imidacloprid 0.20 mL L -1 were found to be equally effective in managing R. pedestris which reduced the population to 0.20 bugs plant -1 . Spiromesifen was recorded to be the best by reducing the population to 10.50 and 16.25 mite plant -1 in cowpea and salad cucumber respectively. Chlorantraniliprole 0.30 mL L -1 and spinosad 0.30 mL L -1 reduced the population of leaf miner to 0.60 and 0.40 larvae plant -1 in cowpea respectively and 0.20 and 0.60 larvae plant -1 in salad cucumber respectively and no larvae of D. indica were recorded in chlorantraniliprole 0.30 mL L -1 and flubendiamide 0.10 mL L -1 treated salad cucumber 15 days after spraying. The dissipation (persistence/ degradation of residues) study showed that the promising insecticide thiamethoxam 0.30 mL L -1 persisted upto 7 and 5 days in cowpea and salad cucumber respectively and imidacloprid 0.20 mL L -1 persisted upto one day in both cowpea and salad cucumber and spiromesifen 0.80 mL L -1 persisted upto 7 and 5 days in cowpea and salad cucumber respectively. Chlorantraniliprole 0.30 mL L -1 and spinosad 0.30 mL L -1 persisted upto 5 and 7 days in cowpea and 3 days each in salad cucumber respectively.From the present study it is concluded that both sucking pests and leaf feeders are causing significant damage in cowpea and salad cucumber under polyhouse conditions. Application of thiamethoxam 0.30 g L -1 and imidacloprid 0.20 mL L -1 effectively manage the sucking pests viz., A. craccivora, M. persicae and R. pedestris. Spiromesifen 0.80 mL L -1 was found to be the best to manage the Tetranychus sp. Chlorantraniliprole 0.30 mL L -1 and spinosad 0.30 mL L -1 were found to be effective in managing leaf feeders in both cowpea and salad cucumber. A harvest interval of 5 to 7 days should be given to ensure the safety of the produce from the polyhouse to the end users.Item Response of cucumber (Cucumis melo L.) to drip irrigation under varying levels of nitrogen and potash(Department of Agronomy, College of Agriculture, Vellayani, 1997) Lakshmi, S; Sasidhar, V KItem Chemodynamics of carbofuran in cucumber(Department of Entomology, College of Agriculture,Vellayani, 1993) Anil Abraham; Naseema Beevi, SA field experiment was conducted to study the chemodynamics of carbofuran in cucumber plants when applied as granule in the soil. The insecticide was applied at two doses of 0.5 and 1.5 kg ai/ha at three occasions viz. sowing, vining and flowering stage of the crop. The residues of carbofuran and its metabolites were estimated from the vines, leaves and fruits at different intervals after the insecticidal treatment using gas chromatographic technique. Distribution of the residues in the various portions of fruit and the effect of different periods of storage on the degradation of residues were also studied in detail. A safe waiting period was also arrived so as to avoid residue hazards in consumption of the fruits. The results indicated that absorption and metabolism of carbofuran in the plant begins soon after its application in the soil. Pure carbofuran and the metabolites, 3-OH carbofuran and 3-keto carbofuran were detected in the vines, leaves and fruit samples at 1,3,7,14,21 and 28 days after treatment. When the different portions of the plant were analysed, the highest level of residues was detected at different occasions. Thus in the vines the peak level of residues was seen on the first day after treatment where as in the leaves and fruits it was on the third seventh day respectively. A gradual decline was noticed thereafter and the residues reached almost non – detectable by 28th day after treatment in all parts of the plant. The effect of peeling on residues was studied in a separate experiment and the results indicated that peeling of fruits could reduce the residues considerably. Distibution of carbofuran residues in different fruit portions was studied and the results indicated that maximum accumulation of the residues took place in the top portions of the fruit followed by middle and basal portions. Comparing the carbofuran residues in the flesh and placenta of cucumber fruits when treated at the flowering stage of the crop it was observed that maximum accumulation of residues of carbofuran took place in the flesh portion when compared with the placenta of the fruit (inner core and seeds). Effect of storing the fruits on the degradation of carbofuran residues showed that metabolism and degradation of the chemical continued even after harvest, during the process of storage. For safe consumption of fruits following carbofuran treatment at the flowering stage a waiting period of 25 and 26 days have to be given when applied @ 0.5 and 1.5 kg ai/ha respectively.