Studies On Heterosis And Genetic Effects On Main Economic Traits Of Luffa

Luffa is an important gourd vegetable crops,with abundant nutritious ingredient and that is of great benefit to human health.Recently,requirements of new luffa cultivars have been increasing gradually with increasing of luffa cultivation area by year.This experiment selected six inbred lines from luffa(L.cylindrica Roem.and L.acutangula Roxb.)population and got 15 F₁ hybrids via dillel cross design.Investigate heterosis and combining ability and genetic effect of main economic traits,find out correlative traits with yield and earliness and importance of every correlative trait,thereby afford theoretical guide to luffa breeding.The main results were as follows:1.Different analysis of parents and F₁ every characters showed that,variance of 19 characters performance of different parents and F₁ was extremely significant.The leaf area,early plant height,rate of fruit development vary mostly greatly;total yield,main stem,single fruit weight had least difference.F₁ hybrids of luffa performed heterosis obviously.Heterosis of the early yield,the early plant height,the single fruit weight,the total yiele and fruit number were performed at a relatively high level.The percent of cross combinations with positive heterosis over better parent was 100%.The percent of heterosis cross combination of the content of soluble protein and dry substance were low,and heterosis of this two quality traits were relatively low.2.P5×P6,P4×P6,P3×P4 had the best heterosis for yield,P5×P6 had the best heterosis for the single fruit weight,P5×P6,P1×P5 had the best heterosis for fruit length, P2×P6,P1×P4 had the best heterosis for fruit number.Interspecific hybrid of luffa indicated that the maiority hybrid F₁ performed heterosis obviously in nutritional growth.Interspecific hybrid of luffa indicated that the majority hybrid F₁ performed heterosis in content of photosynthesis pigment and photosynthesis rate.significant correlation between the photosynthesis pigment and photosynthesis rate,the heterosis of photosynthesis pigment and photosynthesis rate in conformation.Positive significant correlation between photosynthesis rate and total yield,but the heterosis of photosynthesis rate and total yield not in conformation.3.Principle components analysis showed that,the four biggest eigenvalues were chosen and their percentage of accumulative variance was 91.54%.Among the traits tested,content of soluble protein,fruit number,leaf area should be selected first.Frist note of female flower,female flowers number,single fruit weight should be chosen second,and finally rate of fruit development.6 parents were classified into 2 groups.Genetic distance and heterosis showed a linear relationship,the largest genetic distance didn't mean the best heterosis.4.Analysis of Combining Ability indicated that the variance of both general combining ability and specific combining ability on all characters were very significant.It's indicated that these characters were influenced by the add effects or non-add effects of gene or both ones.There were greatly difference among various characters on GCA and SCA.P3 and P6 with the better comprehensive characters which can be directly used in luffa breeding program;P3×P6,P5×P6,P1×P5,P4×P6 with higher heterosis have potentiality of increasing yield production.5.The studies of genetic effect showed that inheritance of early yield,total yield,content of soluble sugar,rate of fruit diameter development were controlled by dominant effect;early plant height,node length,rate of fruit length development,fruit number,main stem diameter,content of soluble protein were controlled by additive and dominant effect together,mainly in dominant effect;first note of female flower,fruit diameter,leave number,fruit shape index were controlled by additive and dominant effect together,mainly in additive effect;female flowers number,fruit length,single fruit weight,content of dry substance were controlled by additive and dominant effect together.For inbred breeding,it is recommended that selection for first note of female flower,fruit shape index,female flowers number,leave number,fruit length be made in earlier generations and selection for Total yield,early yield,main stem diameter,rate of fruit development,fruit number be conducted in advanceded generations.,fruit diameter, content of dry substance were bigger effected by environmental variance.6.The result of correlation analysis showed very significant positive correlation between the early yield,the fruits number,the single fruit weight,early plant height and the total yield..The very significant positive correlation between the early yield and early plant height,leave number,fruit number,very significant nagative correlation between the early yield and the first node of female flower.The results on path analysis revealed that the total yield was affected mainly by three agronomic traits,includes the fruits number,the single fruit weight and the rate of fruit length development.The multiple regression analysis showed the fruits number and the single fruit weight were the key component traits of total yield.Therefore,these two traits could be taken as main selection traits for high yield.