Changes of leaf morphology during the occurrence of wrinkled leaves in southern soybean and its effects on yield traits

【Objective】To investigate the effects of crinkle leaf on soybean leaf morphology and yield in South China, which could assist to clarify the impact of crinkle leaf on leaf morphology,agronomic characters and yield-related characteristics of soybean and reveal the occurrence mechanism of soybean crinkle leaf in South China.【Method】A randomized block trial design was used to research effects on leaf morphology,chlorophyll content,photosynthetic gas exchange parameters,agronomic traits,yield and yield-related traits in two crinkle leaf heterozygous lines:GY_C(crinkle leaf line) and GY_N(normal line).【Result】After the occurrence of crinkle leaf,the parenchyma of the main vein and the wrinkle spaces of the crinkle leaves thickened,but spaces at the leaf edge became thinner. Palisade tissue and spongy tissue were arranged irregularly at the wrinkled spaces and multi-layer parenchyma cells appeared at the leaf margin. With crinkle leaf occurrence,morphological indexes such as the fresh and dry weights of soybean leaves and petioles,petiole length and thickness,leaf length and width,as well as the leaf area decreased significantly(P<0.05 the same below). The distribution of chlorophyll content in wrinkled leaves was uneven,but had no significant effect on photosynthetic gas exchange parameters(P>0.05). With the occurrence of crinkle leaf,soybean matured in 3.33 days on average than those without it. Stems became thinner,with a decrease in lodging resistance and the agronomic characters such as plant height,bottom pod height and the number of main stem nodes also tended to decrease. However,these differences varied in different years of observation. Crinkle leaf resulted in the reduction of yield-related traits such as plant dry weight,pod and seed numbers per plant,seed weight per plant and 100 seeds weight. The average yield of GY_C was 43.11% lower than that of normal leaf material from GY_N in two years. Seed protein content of the crinkle leaf material tended to decrease and the seed oil content tended to increase,but with variation in different years.【Conclusion】Morphologically,the main cause of soybean leaf wrinkle in South China is that the leaf margin cannot stretch normally. With the occurrence of wrinkled leaf,the soybean leaf area and the accumulation of plant dry matter decreases,with a shortening of the growth period and a decrease in lodging resistance. Crinkle leaf of soybean in South of China seriously affects the yield and yieldrelated traits such as grain weight.