| Twenty-one early-maturing crosses covering four types of cross were obtained from seventeen early-maturing varieties such as NEA-303 and ten varieties and breeding lines with good comprehensive traits. Good early-maturing parents and crosses were evaluated through analysis of variance and Duncan's test. Separation trends of yield components in separating progenies of these early-maturing crosses were described. In addition, heritability for ten characters (early production of marketable tubers, tuber weight per hill, tuber number per hill, mean tuber weight, specific gravity, eye depth, skin smoothness, skin color, flesh color and tuber shape) was calculated in the seedling generation. The results were as following:1. Favorita and KE83YU64 combining early production of marketable tubers of preferred sizes and high yield with good other economic characters were selected as the most suitable for use in breeding for earliness. could be used to breed potato with special skin color. Early Rose×FL1533, Success×Caribe and KE83YU64×Snowden were 3 combinations with good overall evaluation. Early Rose×FL1533, Japan Early×KE83YU64 and ×HU9058-2 were special combinations, from which superior clones with purple or red flesh could be obtained.2. Correlations between parents and seedling generation showed that significant positive correlations and high significant positive correlations existed for skin color and tuber shape. But differences were found for genetic effects of the parents.3. Frequency distributions on yield of marketable tubers in all crosses types appeared similar and were of asymmetry with many peaks, especially in 20% and 40%~50% two places. It may be assumed that heredity of potato early production of marketable tubers is controlled by two major genes and many minor genes together. Frequency distributions of tuber weight, tuber number and mean tuber weight per hill were similar in all cross types and were continually declining with majority at the low value. Greater yield advantages existed in the type of AT because of combining unlike. There was greater hereditary difference in controlling tuber weight per hill in different female parents. Frequency distributions of specific gravity of tubers were showed in normal and were identical basically in four types of cross. But there is obviously rising at the high value end inthe type of TA. Thus Neo-tuberosum was. superior to improve starch content. Both parents influenced the separation of offsprings in the trait of potato shape.4. Broad sense heretability and narrow sense heretability varied broadly among different characters, respectively from 50.71% to 88.24% and from 7.14% to 56.96%. High broad sense heretability and narrow sense heretability for skin color, tuber shape, specific gravity and tuber number per hill were observed, which suggest that their heritable effects are important. Low narrow sense heretability, and thereby significant non-additive genetic effects were observed for other traits. It was confirmed that additive effect of female parent was more important to tuber number per hill and specific gravity than by it of male parent. Additive effect of male parent was more important to the heredity of skin color and tuber shape.5. There was significant positive correlation between early production of marketable tubers and mean tuber weight in all types of cross, which suggest that early production of marketable tubers depends on tuber size in early-harvest. Early production of marketable tubers was significantly positively correlated with yield per hill in two types of TT and AT. In the type TT, significant negative correlations existed between early production of marketable tubers and tuber number per hill. Early production of marketable tubers and specific gravity were significantly positively correlated in the type TA and early-maturing materials with high starch content could be obtained from it. |
