1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)

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Author: search.filters.author.Jayalekshmy, V GHas files: Yes

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    Gene recombination for resistance to bacterial wilt and yield components in brinjal
    (Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 1988) Jayalekshmy, V G; Gopinathan Nair, V
    Brinjal (solanum melongena) is an important vegetable crop of India. It's cultivation is threatened by the bacterial wilt disease caused by Psuedomonas solanacaarum in many places. The cultivation of resistant high yielding varieties is the only effective method of controlling the disease. But the assocation of bacterial wilt resistance with poor yield has obstructed conventional breeding approaches aimed at, deriving useful' recombinations. The present study explores the possibility of developing a resistant high yielding variety by selection in the segregating generation of inter varietal crosses. The plants of the crosses between three resistant varieties, SM-6, SMI-10 and Pusa purple cluster with the susceptable variety Pusa purple long as the male parent, were selfed. The seeds were sown and seedlings raised under two environments, (i) in the field where there is chance for natural incidence of bacterial wilt. (2) in pots with sterilised soil under healthy condition, in both the experiments, mean, variance and correlation coefficients of yield and yield contributing characters were estimated. Study of f2 variability has revealed that, the characters plant height number of fruits per plant and weight of fruit are governed by polygenes. The characters, number of days to first harvest, number of days to final harvest and weight of fruits per plant were governed by major genes with late bearing and low yield dominant over early bearing and high yield respectively. Comparison of means and variances under healthy and infected condition gave an insight into the influence of selection on the expression of these characters. Natural selection for resistance eliminated the early bearers and high yielders leading to directional selection in favour of late bearers and poor yieldes.
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    Identification of the donors for blast resistance from traditional rice varieties of Kerala using functional markers
    (Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2014) Henry Nickolas; Jayalekshmy, V G
    The research project entitled “Identification of the donors for blast resistance from traditional rice varieties of Kerala using functional markers” was carried out in the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, Thiruvananthapuram and farmer’s field at Pattambi, Palakkad district during 2012 - 2014. The major objectives of the study were to identify the traditional rice varieties with blast resistance genes (Pi 1, Pi 2, Pi kh) using associated functional markers and the field scoring of the lines under disease stress condition. In the present study, thirty traditional rice varieties of Kerala were taken for resistance gene source identification and field level evaluation. The selected rice varieties were screened for the presence of the reported blast resistance genes Pi 1, Pi 2 and Pi kh using three SSR (Simple Sequence Repeat) markers RM224, RM527 and RM206 respectively. C101Lac (Pi 1), C101A51 (Pi 2) and Tetep (Pi kh) from DRR, Hyderabad were taken as the resistant gene source check. Functional marker analysis showed the presence of gene Pi 1 in nine varieties. Twenty varieties showed the presence of gene Pi 2 and six varieties showed the presence of gene Pi kh. Among these, three varieties were having a gene combination of Pi 1 and Pi 2. Three varieties were having genes Pi 2 and Pi kh and two varieties had Pi 1 and Pi kh gene combination. Five varieties did not show the presence of molecular marker linked to any of the genes under study. Field screening was done for scoring the varieties for blast disease resistance by growing in the disease prone farmer’s field at Pattambi. From screening, ten varieties were found to be moderately resistant and fifteen varieties displayed moderately susceptible response. Analysis of variance of the infection index calculated from disease score showed that, nine varieties were having low index and they were on par. All the remaining varieties showed susceptible response. None of the varieties were immune or resistant. Popular rice varieties Uma and Jyothi showed a high infection index. Comparing the disease score and the presence of genes, it was inferred that, genes Pi 1 and Pi kh in combination, imparted moderate resistance under Kerala condition. Varieties Parambuvattan and Kavunginpoothala having these two genes showed low infection index in the field screening. Considering single gene effect, gene Pi 1 imparted moderate resistance. Varieties Thekkan chitteni and Njavara from Kunnathoor are having this gene showed a low infection index. Pyramiding of genes Pi 1 and Pi kh can impart durable resistance to rice varieties of Kerala. Parambuvattan and Kavunginpoothala having these two genes in combination can be used as donors for the genes.