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20004
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Subject: Plant Breeding × Author: KAU × End date: 2000 × Start date: 2000 × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Heterosis and combining ability in melon
    (Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2000) Deepthy, R; KAU; Wilson, D
    The current research programme on 'Heterosis and combining ability in melon (Cucumis melo (L.) var. conomon) was carried at the Department of Plant Breeding and Genetics, College of Agriculture, VeIl ay ani during 1998- 2000. The objectives were estimation of various genetic parameters, heterosis and combining ability effects of parents and hybrids. The experimental material consisted of seven parents and their 21 F 1 hybrids (without reciprocals). Analysis of variance revealed highly significant difference among the genotypes for all the 21 characters studied. The genotype P3 topped in mean performance for yield and many yield attributes. The hybrids P2 x P6 and P2 x P3 were superior in yield and fruit characters, whereas P6 x P7 was the best for keeping quality, yield and crop duration. Genetic parameters like PCV, GCV, heritability and genetic advance were high for keeping quality, yield, sex ratio and mean fruit weight. Environmental component of variation was negligible for majority of traits. Significant heterosis was observed for all the characters studied. P3 x P 4 showed maximum standard heterosis for yield whereas, P2 x P 6 showed maximum relative heterosis and fruit characters and earliness traits. Variance due to GCA and SCA were significant for all the traits studied. P3 was the best general combiner for yield, fruit diameter, mean fruit weight and fruit length and P2 was the best for node characters and crop duration. The hybrid P6 x P7 was the best specific combiner for yield. Combining the mean performance, SCA effects and standard heterosis, P2 x P6 was identified as the superior cross in terms of yield and yield attributes whereas P 4 x Ps was the best for various flowering traits.
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    ThesisItemOpen Access
    Characterisation and evaluation of the rice cultivar njavara
    (Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 2000) Srinivasa Reddy, G; KAU; Elsy, C R
    Characterization and evaluation of the rice (Oryza saliva L.) cultivar Njavara was undertaken in the Department of Plant Breeding and Genetics and Biochemistry Laboratory, College of Horticulture, Vellanikkara during 1997-1999 with an aim to characterize Njavara genotypes based on morphological and biochemical studies and to evaluate its nutritional qualities. Morphological characterization indicated that the thirteen Njavara genotypes were distinct among themselves and the Njavara genotypes NI (Njavara type from Mulloorkara, Thrissur), N2 (Njavara type from Chittoor, Palakkad), N5 (Njavara type from Edavanna, Malappuram), NIl (Njavara type from Pattambi, Palakkad) and NI3 (Njavara type from Thootha, Palakkad) yielded on par with the check variety Ptb-IO, eventhough they were having extra short growth duration compared to Ptb-I 0. Biochemical characterization revealed the possibility of utilizing peroxidase, esterase and protein polymorphism for identifying the Njavara genotypes especially NI (Njavara type from Mulloorkara, Thrissur) , N2 (Njavara type from Chittoor, Palakkad), N3 (Njavara type from Chittoor, Palakkad) and N4 (Njavara type from Chittoor, Palakkad) and also for the identification of Njavara as a cultivar. Selecting some other isozymes coupled with enzyme activity studies and opting for molecular markers were the other strategies suggested for characterization of Njavara genotypes. Majority of the Njavara genotypes expressed high protein content than Ptb-l O. The genotypes N2 (Njavara type from Chittoor, Palakkad) and N8 (Njavara type from Alwaye) were recommended to be included in weaning and invalid foods due to high protein content. The genotypes N2 (Njavara type from Chittoor, Palakkad), N3 (Njavara type from Chittoor, Palakkad) and NI2 (Njavara type from Thrissur) appeared to have higher number and content of free amino acids. Most of the Njavara genotypes had intermediate amylose and as such may not have any problem with respect to consumer preference. Starch grain characterization revealed that starch grain size could be used for varietal characterization in conjunction with morphological and biochemical markers. Absence of flavonoids in Nj avara grain indicated its nonaromatic nature. The genotype N7 (Njavara type from Tellicherry, Kannur) was found to have better digestibility due to low amylose content, high amylase activity and high soluble carbohydrate content. Variability studies indicated that fat content, straw yield and grain yield provided a good genetic base for selection. Correlation and path studies revealed that grain yield could be improved by simultaneous selection for high straw yield and longer leaves while selection for wider leaves, longer ligules, increased number of days to 50 per cent heading, longer panicles and long duration genotypes favour high free amino acid content. Low amylase activity, short and narrow leaves, shorter panicles, low 1000 grain weight, slender grains, short duration genotypes and smaller starch grains were observed to favour high protein content and selection for tall culms, high 1000 grain weight and bold grains was found to favour high amylase activity:
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    ThesisItemOpen Access
    Genetic and physiological analysis of ratooning in rice
    (Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 2000) Ambili Nair, S; KAU; Rosamma, C A
    The present investigation 'Genetic and physiological analysis of ratooning in rice (Oryza sativa L.)' was conducted at the Agricultural Research Station, Mannuthy during 1999-2000 to study the main crop as well as ratoon crop behaviour of different rice genotypes. The study was carried out to determine genetic variability among the different genotypes used. The study was also aimed at identifying morphological and physiological characters for a genotype of rice with high productivity when main and ratoon crop yields are combined together, through correlation and character association studies. Suitable selection indices were also formulated for identifying superior genotypes. Among the 50 genotypes evaluated in the main crop 24 showed regrowing ability. Of these five varieties viz. CO 43, IR 20, White Ponni, Ponmani and Mangala Mahsuri recorded better ratoon performance. The ratoon crop characters were less pronounced compared to the main crop characters except chlorophyll contents. But the above mentioned genotypes 'exhibited a higher intensity of character expression in both crops compared to the remaining genotypes. The estimates of GCV, heritability and genetic gain were high in the caseofratoon crop for most of the characters studied. Present study revealed that higher total yield can be achieved with a main crop having long duration and increased number of unproductive tillers plant". Ratoon yield can be improved by a better performing main crop with characters such as long duration, more number of grains panicle", more number of unproductive tillers plant" and reduced grain production day". Ratooning ability was considered as an index of the ratoon performance but in the present study ratooning ability recorded a negative direct effect on yield, indicating that this cannot be used as a true index to assess the ratoon performance. The various genetic and physiological analysis thus revealed that the varieties viz. IR 20, Mangala Mahsuri, White Ponni and Ponmani can be recommended as genotypes suitable for ratooning in Kerala. By using these about one third of the main crop yield can be achieved without increasing the land area. Total yield recorded 1;>y these genotypes were also significantly high.
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    ThesisItemOpen Access
    Genetic Analysis In F2 And F3 progenies Of selected Crosses Of Rice Varieties Of Diverse Origin
    (Department of Plant Breeding and Genetics, College of Horticulture,Vellanikkara, 2000) Faseela, K V; KAU; Rajan, S
    The research project 'Genetic Analysis in F2 and F3 Progenies of Selected Crosses of Rice Varieties of Diverse Origin' was carried out in the College of Horticulture, Kerala Agricultural University, Vellanikkara, Thrissur durinq the period January to December, 1998. The major objectives of the study were to understand the various genetic parameters of characters under study, identification of yi&ld components and formulation of selection model so as to isolate promising lines having desirable ideotypic features • from the segregating generations. The high yielding varieties developed from such lines will have a broad genetic base as the parents of selected crosses are of diverse origin. Components of heritable variation revealed that the characters showed decreased trend of variability from F2 to F3. PCV was higher than GCV in both generations for all the characters studied. Low PCV and GCV were observed for grain length, panicle length and duration to 50% flowering in both generations, while grain density showed low PCV and GCV in F3 only. In general, broad sense heritability estimates were observed to be higher in F2 than F3. The characters, plant height at harvest, total tillers plant", LIB ratio, 1000 grain weight, secondary branches panicle' and tertiary branches panicle:' provided great help in direct selection from phenotypic performance, as they exhibited higher values of genotypic coefficient of variation, heritability and expected genetic advance. The .. character, grain length showed little scope of improvement through selection due to low GCV and GA . • Correlation studies in F2 and F3 revealed that positive correlation existed between yield and component characters, namely, total tillers, panicle bearing tillers and tertiary branches panicle". Negative correlation was observed for 1000 grain weight with yield in both the generations. Panicle length and duration to 50% flowering exhibited absence of association with yield in F2 and F3, which indicate that these traits can be recombined as desired. In F3, LIB ratio and grain length exhibited positive correlation and grain breadth exhibited negative correlation, with yield, while these characters showed absence of association with yield in F2• Plant height and number of grains panicle:' exhibited negative association with yield in F2 where as number of grains panic!e' exerted positive association with yield in F3 and plant height showed absence of association with yield in F3. Genotypic correlation among di~ferent yield components in F2 and F3 revealed that semidwarf plants with higher number of productive tillers produced grains with higher LIB ratio and lesser grain weight, which in turn increased the yield. The study also showed that, when number of grains and compactness of• panicles increase, grains become more slender with reduced grain weight. Study of path coefficient analysis revealed that all the characters influenced the yield directly or indirectlv through some other traits. The correlation and path analysis study suggested that during selection, breeder should give emphasis on" semidwarf olant stature, higher number of productive tillers, compact panicles, reduced number of secondary branches, high LIB ratio of grains with reduced density and weight. A selection model was formulated consisting of the characters, , namely, yield ha:'. total tillers plant". LIB ratio, grain breadth and grain density. Using this model, ranking of 105 genotypes in F3 was done and identified that the accessions, V 82 and V 89' belonging to lA 36 x Mattathriveni, were the best genotypes. Study revealed that all the four crosses namely, Vytilla 3 x Mattathriveni, Vytilla 3 x Kaohsiung Sen Vu 338, Mattathriveni x Mahsuri and lA 36 x Mattathriveni, were promising enough to derive superior segregants, the best among them being IR 36 x Mattathriveni. The plants with red kernel, identified in F3 of the cross IR 36 x Mattathriveni, can be used for the development of high yielding varieties with red kernel and preferable cooking qualities suited to Keralites, as well as resistance to biotic and abiotic stresses. This investigation also suggested that crosses from parents of diverse origin will broaden the genetic base of the varieties to be developed in future and will help to break the yield plateau in rice.