. GENETl'C' ANALYSIS OF HIGH YIELDING RICE VARIETIES OF DIVERSE ORIGIN By VANAJA, T. THESIS Submitted in partial fulfilment of the requirement for the degree of mortar of ~bilosopb!' in ~gritulturt Faculty of Agriculture Kerala Agricultural Univ~rsity DEPARTMENT OF PLANT BREEDING AND GENETICS COLLEGE OF HORTICULTURE VELLANIKKARA. THRISSUR. 680654 KERALA, INDIA 1988
DR. LUCK INS C. BABU Associate Dean (i/c.) College of Forestry Kerala Agricultural University CERTIFICA TE Cenified that this thesis entitled "GENETIC ANALYSIS OF HIGH YIELDING RICE VARIETIES OF DIVERSE ORIGIN" is a record of research work done independently by Ms. Vanaja, T., under my guidance and supervision and that it has not previously formed the basis for the award of any degree, fellowship or associateship to her. Ve IIani kkara Ir'H./<1~ ~. u., ;:::::---- DR. Luckins C. 8abu Chairman, Advisory Committee
ABSTRACT The research project 'Genetic Analysis of High Yielding Rice Varieties of Diverse Origin' was carried out in the College of, Horticulture, Kerala Agricultural University, Vellanikkara, Thrissur during the period 1995-'98. The major objectives of the study were to understand the genetic architecture of high yielding rice varieties of diverse origin so as to evolve appropriate breeding methodology, to isolate promising lines having the new ideotype concepts from the segregating generations and to identify alternative source of cytoplasmic male sterile system suitable to warm humid climatic conditions experienced in Kerala. The study, about components of heritable variation revealed that the characters, number of panicles m-2, number of tertiary branches panicle-1,.j: yield ha-1, spikelet sterility percentage and alkali spreading value exhibited,...' high broad sense heritability coupled with high expected genetic advance and high genotypic coefficient of variation. High broad sense heritability and high expected genetic advance coupled with moderate genotypic coefficient of variation were manifested by the characters, namely, height of plant at harvest, second uppermost internodal length, length of flag leaf,, ratio of vegetative phase to reproductive phase, number of spikelets panicle-1, number of grains panicle-1, LIB ratio of grain, milling percentage, amylose content, volume expansion ratio and water uptake.
Correlation studies revealed that the principal yield determining components in rice are harvest index, number of tertiary branches panicle-', number of panicles m-2, number of grains panicle-', number of spikelets panicle-', ratio of vegetative phase to reproductive phase, 1000 grain weight, number of days to 50 per cent flowering, number of days to harvest and spikelet sterility percentage. While selecting genotypes for higher yield potential, emphasis should be given for comparatively lon~ vegetative period, short period from panicle ini~iation to 50 per cent flowering and long ripening period. A selection model was formulated consisting of the characters, namely, yield ha-1, harvest index, number of days to harvest, number of tertiary branches panicle-', ratio of vegetative phase to reproductive phase and number of grains panicle-1. Cluster analysis revealed that there was no, parallelism between geographical distribution and genetic diversity.,"(he 56.,. genotypes representing different eco-geographical regions were grouped into nine clusters based on genetic distances. Combining ability studies showed that both additive and non-additive gene effects were important, with predort/.inance of non-additive gene action, for all the characters except for 1000 grain weight, second uppermost internodal length and height of plant at harvest.
The varieties Vytilla3, Mahsuri, Mattatriveni and Karthika were identified as good general combiners. The varieties Mahsuri, Karthika, Vytilla 3, Mattatriveni and IR62030-18-2-2 showed pronounced cytoplasmic effect on yield and various yield contributing characters. The crosses Vytilla 3 x Mattatriveni, Mahsuri x Vytilla-3 an,d Mahsuri x Mattatriveni are recommended for recombination breeding. The crosses Vytilla 3 x IR36, Vytilla 3 x IR60133-184-3-2, PK3355-5-1-4. x Bhadra, Vytilla 3 x Mattatriveni, Karthika x Bhadra, PK3355-5-1-4 x Karthika and PK3355-5-1-4 x IR62030-18-2-2 are recommended for heterosis breeding. The cytoplasm of Vytilla 3 (an improved saline tolerant variety of Kerala) was identified as an alternative source for cytoplasmic male sterility in rice, suitable to warm humid tropical climate, experienced in Kerala. The varieties IR36 (international check) and Hraswa (extra short duration high yielding variety of Kerala) are the proposed maintainer lines. Mattatriveni is the proposed restorer line for the proposed IR36 'A I line and Hraswa 'A' line. The generation mean analysis using six parameter model revealed that both additive and non-additive gene effects played an important role in the inheritance of yield and important yield components, with predominance of dominance, additive x additive and dominance x dominance type of gene effects.
Results of inbreeding depression indicated absence of reduction in vigour in the F2 generations for yield emd all other yield attributes. Investigation on pattern of inheritance of kernel colour revealed that kernel colour in rice is a complex qualitative character. Each red and white colour may be separately controlled by two or more sets of genes having both inhibitory and duplicate type of gene interactions with predominance of inhibitory type gene interaction. From 22F2 generations, seven early stabilized promising lines and 26 promising segregants were selected. Two early stabilized lines were found to possess most of the ideotype features proposed by IRRI with preferable cooking quality characters. Their further evaluation and multiplication are being carried out at the Agricultural Research Station, Mannuthy, Kerala Agricultural University. By hybridization, it was possible to successfully transfer the non sticky nature and red kernel colour of Mattatriveni to a high yielding Taiwan variety whose kernel is white and sticky on cooking. The gene action studies revealed that there is ample scope for yield improvement in rice both through pedigree breeding and heterosis breeding. As yield and yield components were fc!und to be under the control of all the
three types of gene actions namely, additive, dominance and epistasis, intercrossing of early segregating generations derived from multiple crosses seems to be the best suited method of breeding for yield improvement in rice. Future line of studies suggested 1. Conversion of the already obtained cytoplasmic male sterile F, crosses to fully sterile CMS lines by repeated back crossing with the respective recurrent parents. 2. Screening from the segregating populations of these cytoplasmic male sterile crosses for 100 per cent cytoplasmic male sterile lines. 3. Confirmation of the restoring ability of the proposed Mattatriveni 'A' line and identification of other restorers. 4. Incorporation of the sterile cytoplasm of Vytilla 3 into other elite genotypes other than IA36 and Hraswa. 5. Screening for cytoplasmic male sterile system in other saline tolerant lines. 6. Screening of promising segregants selected, for high yield and quality with multiple resistance to pest and diseases, for developing varieti~s suited to various climatic and soil conditions of Kerala. tl\l-ta\