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1984 - 19872
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Author: Jayasree, P K × Author: KAU × Start date: 1984 × Type: Thesis ×
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    ThesisItemOpen Access
    Yellow vein mosaic disease of pumpkin in Kerala
    (Department of Plant Pathology, College of Agriculture, Vellayani, 1984) Jayasree, P K; KAU; Balakrishnan, S
    Yellow vein mosaic disease of pumpkin ( Cucurbita moschata Dutch. ex Poir) caused by a virus, was investigated which was prevalent in Vellayanl and nearby localities. The symptoms appeared as faint yellowing of finer veins which later on develop into characteristic vein yellowing. In advanced stages of infection, chlorotic areas were seen on the leaf lamina along with vein yellowing symptoms. The size of the leaves was reduced markedly.The growth of infected plants was severely retarded. The infected plants produced less female flowers and when Infected at a later stage produced undersized fruits. Histopathological studies showed a reduction in thickness of the chlorotic portions of the infected leaves and the palisade cells were shortened and loosely packed. The mesophyll cells contained only few chloroplasts. The virus was not sap transnissible. But it could be transnitted through grafting* The virus was hot found to be transmitted through seeds.
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    Efficiency of thiobencarb in dry sown rice
    (Department of Agronomy, College of Horticulture, Vellanikkara, 1987) Jayasree, P K; KAU; Abraham, C T
    A field experiment was conducted at the Agricultural Research Station, Mannuthy of Kerala Agricultural University during the first crop season of 1986 to find out the best time and method of application of thiobencarb in dry sown rice. The treatments included combinations of six time and two method of applications and two controls (un weeded and hand weeded), laid out in RBD with three replications. The results showed that the count, dry matter production and nutrient removal of weeds were appreciably reduced by the weed control treatments, particularly by the spray applications at 6 and 9 days after sowing. Effective control of the weeds during the critical stages of the crop was obtained for the spray treatment. , while the new flushes of weeds after each hand weeding posed some competition in the hand weeded plot. The weed control efficiency was highest during the critical stages for the spray applications at 6 and 9 days after sowing, even higher than that of hand weeding. The herbicide did not produce any phytotoxicity symptoms on the crop. Tiller production was found to be adversely effected by weed competitions whereas the crop plants tended to grow taller with increased weed density. A significant negative correlation was found to exit between the crop and weed dry matter productions. The spray treatments at 6 and 9 days after sowing produced higher crop dry matter and resulted in maximum uptake of nutrients during the critical stages. The spray applications at 6 and 9 days after sowing gave significantly higher values of the yield attributes viz., the productive tillers per hill, length of panicle and number of grains per panicle, resulting in higher grain yields on per with the hand weeding. These treatments recorded higher straw yields also. The weed index values were lower for 6 and 9 days treatments after sowing. In terms of return per rupee invested, the spray application of herbicide at 6 days after sowing was the best.