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Author: search.filters.author.Gopinathan Nair, VStart date: 1970

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    Association of yield and its components in bhindi
    (Kerala Agricultural University, 1988) Sheela, M N; MAnikantan Nair, P; Gopinathan Nair, V
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    Tiller emergence in rice and mutation frequency in the different ear categories
    (Kerala Agricultural University, 1979) Gopinathan Nair, V
    Rice seeds were treated with two doses each of gamma rays and EMS. The tillers on Mj plants were classified according to their node positions. The frequencies of emergence for the various tiller categories were estimated. The M2 generation was raised as M! ear progenies. Chlorophyll mutation frequency and segregation ratio were estimated in the different ear categories. The frequencies of emergence for the various categories of tillers were different. The main shoot developed with the highest frequency followed by the primaries and the secondaries. Tillers in the axils of the coleoptile and the first primary leaf did not normally develop. The frequency of emergence of primary tillers increased upto the fourth and thereafter giadual'y decreased. Early primaries developed more secondaries than later ones. Mutation frequency of the main ear did not differ appreciably from that of primary ears Secondary groups (4) and (5) mutated more frequently than the respective primaries. The segregation ratios for the main ear and primaries were mostly similar. The ratios for the secondaries were higher. This high segregation ratio indicates that secondary ears are derived from smaller number of initial cells.
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    Interrelation of induced chlorophyll and viable mutations in rice
    (Kerala Agricultural University, 1976) Gopinathan Nair, V
    Rice seeds were treated with radiations and chemical mutagens and mutation frequencies were estimated in the M, generation. The proportion of viable to chlorophyll mutations changes with the mutagen. The total mutation frequencies were less than the sum of chlorophyll and viable mutation frequencies at higher doses of EMS indicating that the incidence of chlorophyll and viable mutations in the same ear primordium was more frequent at these doses.
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    Embryonic differentiation in rice seeds as revealed in mutational analysis
    (Kerala Agricultural University, 1976) Gopinathan Nair, V
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    Effect of combined mutagenic treatments on sensitivity and mutation frequency in rice
    (Kerala Agricultural University, 1977) Gopinathan Nair, V
    Puce seeds were subjected to two sets of combination treatments of radiations and NMH. The effects of mutagenic treatments in the MI and M2 generations were recorded and discussed. Mutation frequencies estimated as number of mutations per 100 M, ears were not higher than the values expected on the basis of additive effects. When estimated as number of mutants per ]00 M plants, the frequencies revealed more than additive effects. The synergistic effect on mutant frequencies was due to increase in the segregation ratio of mutants. This effect was more pronounced at the higher dose combinations of fast neutrons and NMH.
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    Mutagenic efficiency of gamma rays in sesamum
    (Kerala Agricultural University, 1977) Ramachandran Nair, N; Gopinathan Nair, V
    Seeds of sesamum Cv. Kayamkulam-l were irradiated with gamma rays at doses 5 to 30 krad. The effects of irradiation in the M and M, generations were studied. The doses employed had no effect on germination, seedling emergence and plant height in the M, generation. With increase in the dose there was a steady decrease in survival and pollen fertility. The frequency of chlorophyll mutation estimated on M, plant basis was higher than the estimate on !V plant basis The mutation spectrum included xantha (yellow) and chlorina (yellow green). Segregation ratio was maximum at 10 krad and minimum at 25 krad. Mutagenic effectiveness and efficiency were high at the lower doses and decreased with increasing doses. These observations indicate that gamma rays at low fo medium doses can be successfully employed for inducing mutations in sesamum.
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    Gamma ray induced viable mutations in sesamum
    (Kerala Agricultural University, 1978) Ramachandran Nair, N; Gopinathan Nair, V
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    Enhancement of the mutagenic effects of nitroso methyl urea in rice through alteration in the period of presoaking of seeds
    (Kerala Agricultural University, 1978) Gopinathan Nair, V
    The effect of presoaking seeds on sensitivity and mutation frequency in rjce was studied. Treatments were given in 3 series le. with 3 doses of M«/JLJ Each series consisted of 11 different periods of presoaking in range of 8 to 48 hours. Mutagenic effects were estimated in the M, and M. generations and interpreted. Sensitivity to NMH increased with the length of presoaking and reached a maximum at 32 hours. There was a decrease in sensitivity when presoaking was extended beyond this period. The time specificity of the sensitivity peak was independant of the dose of mutagen and the criteria adopted for its estimation. The peak period of sensitivity corresponds to the time of DMA synthesis in the initial cciis It appears that the first DMA synthesis in the initial cells is responsible for the peak sensitivity at 32 hours presoaking. The frequency of chlorophyll mutations increased with the length of presoaking reaching a maximum at 40 to 44 hours. Conspicuous increase were obtained during the periods 16 to 20 hours and 24 to 28 hours. The enhanced efficiency during the 16 to 28 hour period can be attributed to the synchronisation of treatment time with the 'S' phase of DMA synthesis. The spectrum of mutations indicated predominance of albino, viridis and chlorina. Xantha and tigrina were very rare and appeared only from 20 hours onwards. The increase in relative per cent of albino with the length of presoaking and the late appearance of Xantha and tigrina were the characteristic features of the mutation spectrum. The change in spectrum with different periods of presoaking indicate scope for further efforts towards attaining mutation specificity.
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    Effect of recurrent and alternate mutagenic treatments in rice
    (Kerala Agricultural University, 1978) Gopinathan Nair, V
    The effects of repeated mutagenic treatment in the M2- and M3- gene. ation* in rice are reported. Recurrent irradiation with gamma rays and alternate treatment with gamma rays and NMH, neither increased the sensitivity of seeds r enhanced the frequency of induced chlorophyll mutations. This indicate that e inspite of its secondary polyploid nature behaves like a diploid in its reppo to the action of mutagens.
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    Anthesis in Indian lemongrass Cymbopogon Flexuosus, stapf
    (Kerala Agricultural University, 1979) Mercy, S T; Gopinathan Nair, V; Luckins C Babu
    Studies were undertaken on the mechanism of anthesis in Indian lemongrass. An inflorescence takes 25 to 32 days for completion of anthosis. The peak period of anthesis is from the 6th day from commencement of anthesis to the 11th day. About 80% of spikes complete anthesis by the 15th day. Anthesis takes place in the morning between 7 and 8.30. !n the sessile spikelets anthesis appears earlier than its appearance in the pedicellate ones. There are four distinct stages in the anthesis of sessile spikelet which take plrce one after the other in quick succession. The most characteristic featrue of anthesis is the slight protogynous nature of the sessile spikelet. Though this is a basic adaptation for cross pollination, the large number of spikeleis opening in a short span of time indicate the possibility for self pollination under field conditions.