Studies On The Performance Of Summer Soybean Planted On Dry Land And Irrigated Land And The Effect Of Pod-seed Characters To Soybean Yield

In this paper, 10 summer soybean varieties (lines) planted at dry land or irrigated land conditions in Henan Province were compared, analyzed and evaluated for their main agronomic characters and their influences on yields through grey correlative degree analysis, identical and different analysis and other methods, The approaches of improving summer soybean yields were presented from the perspectives of breeding, varieties utilization and cultivation management. 14 soybean varieties planted in different provinces of China were used as experiment materials and effects of pod and seed traits on yields were analyzed through correlation analysis and path analysis. Methods of improving pod and seed traits in high yield soybean breeding were presented as well. The main results were as follows:1. Main agronomic character (except seeds per pod) values of summer soybean decrease in dry land conditions compared with irrigated land conditions. But the reduction degrees are different: yield per plant (—59.4%),pod number of caulis (—41.3%),pod number per plant (—40.5%),pod number of branches (—37.9%),number of seeds per plant (—36.5%),100-seed weight (—35.6%),plant height (—22.5%),diameter of stem (—19.9%),number of branches (—13.4%),node numbers of caulis (—10.5%)。The results showed that: in dry land conditions, yield per plant is reduced the most, the second is characters of yield components (pod number,pod number per plant and 100-seed weight) and the third is morphologic characters (plant height,diameter of stem,number of branches and node numbers of caulis).2. Grey correlative degree analysis showed that, in dry land conditions, the order of correlative degree of agronomic characters to yield per plant is as follows: diameter of stem＞node numbers of caulis＞100-seed weight＞pod and seed numbers＞plant height＞seed numbers per plant＞pod numbers per plant＞pod number of branches＞pod number of caulis＞number of branches. In irrigated land conditions, the order is pod and seed numbers＞pod number of caulis＞pod numbers per plant＞seed numbers per plant ＞100-seed weight＞diameter of stem＞plant height＞node numbers＞number of branches＞pod number of branches. According to the above results we can see that the effects of agronomic characters to yield per plant differ in different soil moisture conditions. In dry land conditions, the agronomic characters which obviously affect yield per plant are diameter of stem, node numbers,100-seed weight and plant height; the agronomic characters of less effects are seed numbers per plant,pod numbers per plant,pod number of branches,pod number of caulis and number of branches. In irrigated land conditions, the agronomic characters obviously affecting yield of per plant are pod and seed number,pod number of caulis,pod number per plant,seed numbers per plant and 100-seed weight; the agronomic characters of less effects are diameter of stem,plant height,node numbers,number of branches and pod number of branches.3. Identical and different analysis showed that, in dry land conditions of west Henan Province, Yudou-23,Yudou-22,Yudou-21 are excellent varieties, Yudou-18,Yudou-25,Luodou-961 are better varieties, Yudou-16,Yudou-19,Yuxi-9725 are general varieties (lines) and Yuxi-9722 is inferior lines. In irrigated land conditions of west Henan Province, Yudou-18,Yudou-22,Yudou-25 are excellent varieties, Yudou-21,Yudou-23,Luodou-961 are better varieties, Yudou-19,Yudou-16 are ordinary varieties and Yuxi-9725,Yuxi-9722 are inferior lines.4. The approaches and methods of improving summer soybean yields are: as for breeding, when selecting varieties, we should emphasize particularly on some characters according to the different ecological and production conditions; as for varieties utilization and cultivation management, in dry land conditions, the limit or sub-limit pod varieties which has wide diameter of stem,more node numbers should be used. Furthermore, Strengthening field management, cultivating intensively, planting timely when soil moisture is suitable, making plant grow stronger and having more pods and seeds, and having plump seeds, will obtain high yield. In irrigated land conditions, the limit pod varieties, which are of middle plant height and lodging resistance, mainly bear pod on caulis, and have appropriate branch numbers and more pods and seeds, should be used. Moreover it is also necessary to pay attention to water and fertilizer management, prevent rapid growth and lodging, exploit single plant yield potential and harmonize relations among individuals in population.5. Correlation analysis of soybean pod and seed traits with yield per plant showed that: traits, such as pod weight per plant,pod numbers per plant,seed numbers per plant, pod hull weight,seed location number per plant,plant height and 100-seed weight, has positive correlation with yield per plant. Pod weight per plant has the most significant positive correlation with yield per plant. Pod numbers per plant, seed numbers per plant,pod hull weight and seed location number per plant has significant positive correlation with yield per plant. But pod hull weight/seed weight ratio has negative correlation with yield per plant. The results indicated that breeding soybean varieties, which has more pod weight per plant,less hull weight/seed weight ratio,more pods and seeds,higher plant height, is the effective way of improving yield per plant.6. Path analysis between pod and seed traits and yield per plant showed that: the direct effect values between plant height,pod weight per plant,seed location number per plant, seed numbers per plant,100-seed weight, pod hull weight,pod hull weight to seed weight ratio and yield per plant are 0.021,0.029,1.265,0.053,-0.056,0.017,-0.348,-0.042 respectively. The agronomic characters, which had positive direct effect on yield per plant, ordered by path coefficient are pod weight per plant,seed location number per plant,pod numbers per plant,plant height and 100-seed weight. The agronomic characters which had negative direct effect to yield per plant are pod hull weight to seed weight ratio, seed number per plant and pod hull weight. Therefore, in order to improve soybean breeding efficiency, we should consider the effects of traits on yield per plant, emphasize the improvement of pod and seed traits which has close relation with yield and, at the same time, pay attention to harmonize the relations among traits.