落花生型間雜交農藝性狀之遺傳變異

Abstract

本研究利用六個分屬於Spanish、Valencia及Virgini。三種植物型各二品系之落花生為材料，進行6×6半互交，分別於1989至1992年春作在農業試驗所進行F,至F。世代之田問試驗，探討落花生莢果及籽粒性狀各世代後裔族群之變異，以及組合力之變化，並比較型問及型內組合的差異性，以供育種之參考。結果顯示：所調查之八個性狀其族群之變異隨世代在之增加而擴大，且型間組合大於型內組合，而型間組合以亞種間雜交組合略大，在八個性狀中莢數、莢重、粒數及粒重等四個性狀的變異係數明顯大於莢果及籽粒長寬的變異係數，從F2族群的超越分離調查亦顯示亞種間的雜交組合較高。在組合力分析結果，F1到F3的GCA及SCA均方值大多數均呈顯著，而且SCA相對增加，顯示SCA的效應仍不能忽略，到F4時SCA均不顯著。六個親本的GCA效應在不同世代差異頗大，很難判斷何者親本較優，因此以早期世代評估親本的優劣，可能會有偏差。比較型間及型內組合的SCA效應，從F邊到F。變化亦大，型內組合在F3及F4多呈負效應，型間組合的Spanish×Virgini。及Valencia×Virginia組合從F2到F4多為正效應。如針對莢果及籽粒性狀進行改良，以Spanish及Velncia兩種型的品系與Virginia型品系進行型間雜交可能較有利。 Six peanut (Arachis hypogaca L.) genotypes, including two of each from Spanish, Valencia, and Virginia types, representing a wide range of genetic diversity, were selected as the parents. A 6 × 6 half-diallel mating design was followed from F1 to F 4 for evaluating the population genetic variability and combining ability of pod and seed traits. The changes in population genetic variability and combining ability parameters among the i and the resulted subsequent generation and the performances of the parameters of inter- and intra-type crosses were investigated. The population variability of crosses increased from F1 to F4 , and those of intertype were larger than intratype of subspecific crosses. The parents and progenies, F1 to F4 generations, were tested in the spring crops of 1989 and 1992. Experimental results indicated that both general and specific combining abilities (GCA and SCA) were significant in most cases. Furthermore, the GCA effects were higher than SCA effects for all traits in the F to F generations. However, theratios of GCA/SCA were low in the later generations. This suggests that the SCAeffects might bemore importantin advancedgeneration. The GCA effects of the sixparents estimatedfrom theF andfrom the subsequent generations varied. Thisfact indicates that combiningability parameters estimated from theearlygeneration mightnot be effective for predicting the performance in later or subsequent generations. Comparing SCA effects of inter- and intra-type crosses showed that Spaniah type × Virginia type and Valencia type × Virginia type combinations had more positive effecets from F generation, Spanish type × Valencia type combinations had negative effects for most traits from F2 generation. This result suggests that crosses between Spanish or Valencia type with Virginia type peanut were promising combinations for pod and seed traits improvement.