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ThesisItem Open Access Induction of polyploidy in kacholam(Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 1996) Ajithmohan, N K; KAU; Pushkaran, KA trial on induction of polyploidy in Kaempferia galanga L. was undertaken at the Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, during the period 1994-'95. A local selection Vellanikkara collected from the genetic stock maintained at AICRP on M & AP was used for the study. The objective was to create variability in kacholam by developing polyploids. The rhizomes of the crop were treated with colchicine for inducing polyploidy. Five concentration of colchicine viz., 0.05, 0.15, 0.25, 0.35 and 0.45 per cent (C2 to C6, C1 being control i.e., 0%) was tried for two time durations viz., four hours and six hours (T1 and T2), the same treatment being repeated on two consecutive days. Two methods of treatment were tried the first (M1) being chemical application in a hole drilled close to the sprouting bud and the second (M2) being the ordinary cotton swab method. Rhizomes with two different stages of bud sprouting were used: (1) with just emerging buds (S1) and (2) buds at an advanced stage of sprouting (S2). The treated rhizomes were planted in the field and their growth was examined. In the end of the crop season, 18 variant plants were identified and they were put to detailed morphological and cytological study in the next growing season. Mitotic study of the parent material confirmed that the chromosome number of kacholam is 55. Of the 18 variants identified one was found to contain 110 chromosomes in the somatic cells. As kacholam is proposed to be a pentaploid the induced polyploid must be a decaploid. The polyploid was obtained from the treatment combination S1M1T1C6. It was characterised by small plant size and reduced vigour. The leaves were thick with reduced size. Stomatal size increased conspicuously with their numbers reduced. The rhizome development was found retarded and the per plant yield was also less. The rhizome morphology was on par with the normal plants. The plant flowered neither in the first season nor in the second. In addition to the polyploid, there other stable variants were obtained from the experiment. They were also characterised by reduced vigour and yield.ThesisItem Open Access Induced mutations in interspecific hybrids of abolmochus(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 1996) Animon, G; KAU; Gopimony, RThe F1 seeds of the cross between Abelmoschus esculentus cv Kiran and the semi- wild species, Abelmoschus manihot were exposed to four different doses (10, 20, 30 and 40 KR) of gama rays and their effects in the first generation were studied. The percentage of seed germination decreased with increasing doses of gamma rays. The treated hybrids have shown delyed germination compared to the control. The survival of plants was found to decrease with increase in dose of the mutagen. The rate of growth of plants and plant height were found to decrease by the treatment with gamma rays. Various chlorophyll and morphological varients were observed in the irradiated population. An increase in pollen fertility was noticed in the irradiated hybrids. But the increased pollen fertility did not show any effect on the seed set. Irradiation delayed the formation of flowers and fruiting. The mean values for number and weight of fruits did not differ significantly among irradiated treatments and was on par with the control F1. The treated hybrids were found to be on par with the control F1 for yellow vein mosaic disease incidence and the important diseases affecting bhindi. The hybrids irradiated at higher doses had become more susceptiable to fruit borer incidence. The hybrids represented more towards the semi-wild parent and have shown considerable heterosis over the cultivated parent and semi-wild parent for most of the economic characters. The hybrids were vigorous in growth habit compared to the parents. The hybrid treatments exhibited significant positive heterosis for days taken to first flowering and last fruiting over the cultivated parent. The hybrids treatments exhibited significant positive heterosis for number of flowers, number of fruits and weight of fruits over both the parents. Significant negative heterosis over the cultivated parent was shown for fruit length by the hybrid treatments. Significant negative heterosis over the cultivated parent for fruit borer incidence was shown by the control and the hybrids irradiated at 10 and 20 KR. All the hybrid treatments manifested significant negative heterosis over the cultivated parent for YVMD incidence. The mutagenic effectiveness in inducing chlorophyll mutations was found to increase with increase in dose of the gamma rays. The mutagenic efficiency estmated on the basis of lethality and injury increased with increase in dose of gamma rays. On sterility basis, the 30 KR treatments was the most efficient.ThesisItem Open Access Gametocidal properties of certain chemical in rice(Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 1996) Manjula, M; KAU; Ibrahim, K KA pot culture experiment was conducted at Instructional Farm, College of Horticulture, Vellanikkara, Kerala during summer 1995 to study the gametocidal properties of three chemicals viz., ethrel, maleic hydrazide and streptomycin in two varities of rice. The study aimed at induction of variable levles of male sterility using these chemicals, with minimum interactions with other factors viz., stage, concentration and variety and also without adversely affecting spikelet fertility and plant growth characters like panicle exsertion. The chemicals were sprayed at concentrations of 4000, 6000 and 8000 ppm at stage-1 (spiketet differentiation stage) or stage-2 (pollen mother cell formation stage) in Annapurna, a short duration variety and Athira, a medium duration variety. The pollen spikelet sterility were observed in main and subsequent panicles. Pollen sterility differed with chemical, concentration and variety in main panicle and with all factors including stage of application in subsequent panicles. The effect of a chemical interacted significantly for pollen sterility with other factors viz., concentration and variety in main panicle and concentration and stage in subsequent panicles. The treatments involving maleic hydrazide were the most effective inducing pollen sterility upto 99.3 per cent. Ethrel was moderately effective in inducing maximum pollen sterility of 48.9 per cent in Annapurna with 4000 ppm at stage-1. Streptomycin failed to induce pollen sterility irrespective of stages and concentrations. Maleic hydrazide produced male sterility in a dose dependent manner. It caused more sterility in main panicle in Annapurna but in susequent panicles in Athira. Pollen sterility to a large extent was due to deformed anthers containing low or no pollen production in MH treated plants. High pollen sterility induced by the chemical was aasociated with high sterility of spikelets (upto 99.7%). Besides, it adversely affected plant height, panicle emergence and panicle exsertion. MH at 4000 ppm appeared to be the most ideal treatment for population improvement programme considering its effects on not only pollen sterility but also other important characters including spikelet sterility. On the other hand, in hybrid rice programme that require almost complete male sterility, MH at 8000 ppm at stage-1 or at 6000 ppm at stage-2 appeared to be more suitable.
