1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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Item Pattern of root activity in bananas under irrigated and rainfed conditions(Department of Pomology and Floriculture, College of Horticulture, Vellanikkara, 1985) Sobhana, A; Aravindakhan, MThe experiments were undertaken with an objective to find out the most active root zone of banana var. ‘Nendran’ employing radioactive 32p. These were conducted in the College of Horticulture, Kerala Agricultural University, Vellanikkara, during the year 1983-84. The field experiments were laid out in randomised block design, with three replications and the plants were raised under normal conditions. While taking into consideration the number, length and diameter fresh and dry weights of roots, all these were found to be more for the rainfed crop than the irrigated. This explains the enhanced production of roots under conditions of moisture stress. The radioactivity was injected at four months ago of the plant. The area around each experimental plant was injected with 32p solution with the help of a dispensette. The different lateral distances used for the 32p injection were 20cm, 40cm, 80cm and 120 cm and the different depths were 5cm, 15 cm , 30cm and 60cm. The third leaf was radio assayed and the 32p counts were used for finding out the percentage of active roots at the various treatment sites. The results of radiotracer studies indicated that maximum percentage of active roots was located at a soil zone covering 20cm distance and 30 cm depth from the base of the plant under irrigated condition, at five and six months age of the plant. The rainfed crop had its maximum percentage of active roots at a soil zone of 30cm deep and 40cm away from the plant. As the lateral distances increased from 20cm to 120cm, a reduction was noticed in the percentage activity of roots accordingly, under both irrigated and unirrigated conditions. But the root activity was not significantly different at different depths for the irrigated crop, which was significant for the rainfed crop. Under high moisture stress roots tend to forage into deeper layers of soil for getting the available water. Hence deeper soil zones had more active roots under unirrigated conditions, compared to irrigated crop, which had more surface active roots. An experiment was also organized to study of the translocation of absorbed 32p to various parts of the plant after flowering under irrigated condition. It was observed that male flowers had maximum concentration of 32p followed by female flowers or fruits. Of the various leaves, topmost younger leaves were found to build up more 32p than matured leaves, indicating a translocation to the developing immature leaves.Item Refinement of management practices for jasmine (jasminum sambac L) in humid tropics(Department of Pomology and Floriculture, College of Horticulture, Vellanikkara, 2007) Smisha, I S; Sobhana, AStudies were conducted at the Department of Pomology and Floriculture, College of Horticulture Vellanikkara, to find out the effect of month of pruning and fertilisers on vegetative and floral characters of J. sambac as well as post harvest trials on extending the keeping quality of flowers. Out of different months of pruning, plants pruned in October showed maximum plant height while those pruned in July showed maximum plant spread. Number of primary and secondary branches were highest in April pruned plants which was on par with July pruned plants. There was no significant difference in the number of productive shoots. Yield was highest for January pruned plants. Hundred flower bud weight and flower bud length were also maximum for these plants. The manurial trial included organic manures, inorganic fertilizers and biofertilisers. Plant height was maximum for treatment containing Azospirillum, phosphobacteria and AMF along with NPK 120:240:240.g/plant per year in the initial months but in later months treatments containing neem cake, groundnut cake and poultry manure showed maximum plant height. Plant spread was highest in treatment containing neem cake 100g, FYM 100g and ground nut cake 100g given at monthly intervals. Productive shoots were also maximum in treatments containing neem cake, groundnut cake and poultry manure. Flower yield was also maximum in treatment containing neem cake, groundnut cake and poultry manure. This was significantly superior to all other treatments. Nutrient analysis revealed that the treatment containing chemical fertilizers had maximum amount of available nitrogen and the treatment containing organic manures had maximum amount of phosphorous in soil. Potassium content was maximum for treatment containing Azospirillum and phosphobacteria. In vegetative stage leaf nitrogen, phosphorous and potassium contents were maximum in treatment containing neem cake, ground nut cake and poultry manure. In flowering stage there was no significant difference among the treatments in the case of nitrogen. Treatment containing neem cake, ground nut cake and poultry manure showed maximum value in the case of phosphorous and potassium. Under post harvest studies packaging treatments containing polythene cover with four per cent perforation showed minimum physiological loss of weight followed by the flowers packed in polythene bag without perforation. Flower buds packed in polythene bag remained fresh up to 36 hours. In chemical treatments aluminium sulphate 25ppm delayed wilting by 42hours in both seasons. This was significantly superior to all other treatments. In chilling treatments time taken to wilt was maximum for flower buds kept at temperature of 200C followed by flower buds kept at temperature of 150C.Item Improvement of dendrobium through hybridisation and in vitro mutagenesis(Department of Pomology and Floriculture, College of Horticulture, Vellanikkara, 2000) Sobhana, A; Rajeevan, P K