• Korean Journal of Plant Resources
• /
• v.20 no.2
• /
• pp.168-176
• /
• 2007

Heterosis, combining ability, genetic components, effective factor no. and heritability for yield of seed cotton per plant, boll no., seeds per boll, seed length, seed width and lint weight per boll were investigated in $5{\times}5$ half diallel set of crosses involving diverse upland cultivars. Both heterosis and heterobeltiosis for yield per plant, boll number, seed length and lint weight showed significantly negative values. Both general combining ability (GCA) and specific combining ability (SCA) showed highly significant. Overdominance was observed for yield per plant, boll number, seeds per boll and seed width, complete dominance for seed length and partial dominance for lint weight. The number of effective factor was estimated as two for yield per plant, boll number and seed length and estimated as one for seeds per boll, seed width and lint weight. Narrow sense heritability was low for yield per plant, boll number and seeds per boll. Broad sense heritability was very high for all the characters excepting lint weight.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.39 no.3
• /
• pp.262-269
• /
• 1994

This study was conducted to clarify high yielding factors of F$_1$ hybrids in terms of the growth characteristics, canopy structure, nitrogen content and nitrogen profile in the canopy. Varieties used in this study were four hybrid rices showing different heterosis in grain yield and their parents. Varieties of Japonica were Reimei (maintainer), TP 681 and TP 1278(restorers), and F$_1$ (Reimei ms ${\times}$ TP 681, Reimei ms ${\times}$ TP 1278) hybrid rices. Those of Indica type were 1378 (maintainer), Milyang 46 and Suweon 287(restorers), and F$_1$ (1378 ms ${\times}$ Milyang 46, 1378 ms ${\times}$ Suweon 287) hybrid rices. High heterosis in F$_1$ hybrid rices were shown in panicles per hill and spikelets per panicle, being greatest in spikelets per panicle. Spikelets per square meter expressed even greater heterosis than those two yield components because of multiplicative effect of them. Heterosisof ripened concentration of leaf nitrogen and steeper gradient of leaf nitrogen in canopy strata but also better productive structure in favor of light interception seemed to have led to higher canopy photosynthesis of F$_1$ hybrids and subsequent higher partition of assimilates for leaf area expantion especially during vegetative growth stage. Higher dry matter production, resulting from these factors, during vegetative stage would have contributed to the production of greater number of spikelets per square meter, and consequently to higher grain yield in F$_1$ hybrids.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.38 no.5
• /
• pp.418-424
• /
• 1993

In order to test combining ability of the cytoplasmic-genetic male sterile(CGMS) and restorer lines with backgrounds of Korean japonica rice varieties, diallel crosses were made among the early maturing CGMS lines Sobaegbyeo A, Odaebyeo A, Gwanagbyeo A and Daeseongbyeo A, and the restorer lines Sobaegbyeo R, Odaebyeo R, Gwanagbyeo Rand Daeseongbyeo R, and among the medium maturing CGMS lines Hwajinbyeo A, Paldal A, Suwon 224 A and Iri 386 A and the restorer lines Hwajinbyeo R, Paldal R, Suwon 224 Rand Iri 386 R, and among the late maturing CGMS lines Nagdongbyeo A, Palkweng A, Hwacheongbyeo A and Milyang 97 A and the restorer lines Nagdongbyeo R, Palkweng R, H wacheongbyeo Rand Milyang 97 R. The fourty eight combinations of the hybrids, their parents and the maintainers were grown in field condition in 1992. General combining ability, relative specific combining ability and relative combining ability for yield of the CGMS and restorer lines were tested. Combining ability of the CGMS lines Odaebyeo A, Iri 386 A, Nagdongbyeo A and Palkweng A, and of the restorer lines Odaebyeo R, Hwajinbyeo R, Hwacheongbyeo Rand Palkweng R was relatively high. Heterobeltiosis for grain yield over the better parent of the early maturing hybrids ranged from -17 % to 15%, and that of the medium maturing ones from -4% to 22%, and that of the late maturing ones from -46% to 30% respectively, Standard heterosis over the standard variety of the early maturing hybrids ranged from -13 % to 12 %, and that of the medium maturing ones from 0 % to 26%, and that of the late maturing ones from -38% to 26% respectively, Positive and negative heterosis for grain yield of the hybrid rices were observed depending on cross combinations, In the positive heterosis hybrids, number of panicles per hill and number of spikelets per panicle contributed mostly to grain yield, while in the negative heterosis hybrids, spikelet fertility and 1000 grain weight were closely correlated to grain yield. Amylose content of the hybrid rices, maintainer and restorer lines was mostly lower than 20 %, and alkali digestion value was higher than 6.0. Grain appearance of the hybrids tested was similar to the korean japonica rice varieties.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.8 no.1
• /
• pp.107-112
• /
• 2004

The combining abilities in the 5 newly evolved thermo tolerant breeds viz., SR6, SR7, SR8 SR9 and SR10 of silkworm Bombyx mori L. and their 15 hybrids were made in a line${\times}$tester crossing programme. Data were analysed for seven quantitative traits i.e., pupation rate, cocoon yield, cocoon weight, cocoon shell weight, cocoon shell ratio, filament length and raw silk percentage under optimum room temperature $(25{\pm}{1^{\circ}C})$ conditions (In case of high temperature $(36{\pm}{1^{\circ}C})$ stress conditions five economic traits except filament length and raw silk percentage) with 3 widely adapted testers i.e., KA, CSR2 and CC1 as lines (females) and testers (males) respectively. The performance at high temperature and low humidity conditions aye only taken into consideration for selecting the best lines/hybrids. Among the lines SR6 exhibited positive General combining ability (GCA) effects for pupation rate, cocoon yield, cocoon weight and cocoon shell ratio traits, followed by SR7 for pupation rate, cocoon yield and cocoon shell weight and cocoon shell ratio. Among testers, KA exhibited positive GCA effects for two quantitative traits cocoon yield, cocoon weight and CSR2 for cocoon shell weight and cocoon shell ratio under adverse temperature conditions. The hybrid SR6${\times}$CC1 and SR7${\times}$CSR2 exhibited significant positive Specific combining ability (SCA) effects for majority of the traits in high temperature stress conditions of rearing. The better parent value of heterosis(Heterobeltiosis) was exhibited by the hybrid SR6${\times}$CC1 for pupation rate, cocoon yield, cocoon weight and cocoon shell weight and SR7${\times}$CSR2 for all the trails evaluated under high temperature conditions. Based on the results, the lines SR6 and SR7 was judged as best combiners and the hybrids SR6${\times}$CC1 and SR7${\times}$CSR2 can be selected for commercial exploitation in tropical climate.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.2 no.2
• /
• pp.123-127
• /
• 2001

In order to introduce bivoltine races in a tropical country like India, it is necessary to have stability in cocoon crop under high temperature environments. Unlike any temperate country like Japan, the rearing conditions/environment, climatic conditions, quality of mulberry leaf and incidence of diseases are unpredictable in India. Geneticists and breeders of all the sericultural countries have experienced the influence of environment during the process of breeding. in order to select efficiently the breeds with high temperature tolerance, it is verb important to analyse clearly the heritability nature of high temperature tolerance. In light of the above, the present study was undertaken to determine the effect of high temperature treatment of (A) $35{\pm}1^{\circ}C$ and 85${\pm}$5% RH for 24 hrs continuously, (B) $35{\pm}1^{\circ}C$ and 85${\pm}$5% RH for 48 hrs continuously and (C) the control (25${\pm}1^{\circ}$ and 65${\pm}$5% RH in the normal rearing condition from the $3^{rd}of5^{th}$ instar on the pure races such as Moria, Nl37 and Cl46 as well as their Fl hybrids. The overall performance indicate that the hybrids are mare tolerant than the pure races. it was also observed that the overall performance declined in those batches where 48 hrs treatment was given. The most interesting observation noticed in this study was that there was maternal effect regarding temperature tolerance as evident from the better performance of those hybrids where the female parent used was more tolerant as pure race.

• Current Research on Agriculture and Life Sciences
• /
• v.1
• /
• pp.11-18
• /
• 1983

This study was performed to obtain the basic informations for red dry pepper fruit with more pericarp weight(or in percentage) with a complete diallel cross(excluding reciprocals) using eight cultivars. Heterosis, combining ability and inheritance of the dry red fruit weight and its components(stem, placenta, seed, and pericarp) were evaluated. The results obtained were summarized as follows : Dry weight/fruit and its four antomical components were heavier in the earlier harvest fruit than in that of the later fruit. They showed 1% significance among parents and $F_1s$, and those of $F_1$ were significantly heavier than in parent. All characters in earlier fruit of parent, however, were higher than in later fruit of $F_1$. Dry weight percentage of pericarp to dry weight/fruit was highest followed by seed. Percentage of pericarp in the later fruit was increased while the seed decreased and percentages of stem and placenta were not differed between the earlier and later fruit. $F_1$ hybrids above the higher parent were observed in all characters. Mean heterosis (%) was positive in all characters while mean heterobeltiosis (%) was negative excepting seed and dry weight/fruit. GCA and SCA variances were highly significant, and GCA vaiances were greater than SCA in all characters. The directions of dominance were positive. Partial dominance was shown in stem, complete dominance in placenta, pericarp and dry weight/fruit, and over dominance in seed. The effective genes were estimated as one for stem and placenta, and two for seed, pericarp and dry weight/fruit. Heritabilities in narrow and broad sense were higher.