Morphological Variation of Pubescence on Leaf Blade and Petiole and Their Correlation with Resistance to Bean Pyralid (Lamprosema indicata Fabricius) in Soybean Landraces

The tip shape,density,length and angle(status)of pubescence on stem,leaf and pod in soybean vary essentially among varieties and materials.This paper aims to reveal the variation of pubescence traits on leaf blade and petiole,their regional characteristics,their mutual correlations and their correlation with resistance to bean pyralid(Lamprosema indicata Fabricius)in Chinese soybean landraces.Significant differences were found in soybean pubescence density,length,angle on leaf blade and angle on petiole,with the range of 4.8-105.9 hairs·10 mm-2(except for hairless landrace),0.22-0.94 mm,0°-88° and 5°-90°,respectively.The numbers of landraces with long pubescence,high pubescence density,big pubescence angle on leaf blade,small pubescence angle on petiole were small relative to their counterparts.Among 393 landraces,127 were of sharp pubescence tip.The pubescence length,angle,tip shape on blade and angle on petiole were relatively differentiated among geographic regions.The pubescence length of landraces from varietal eco-region I is longer,the pubescence angle on leaf blade from varietal eco-region I and II were bigger,the blunt tip shape in varietal eco-region I,II and III were more and the pubescence angle on petiole from varietal eco-region I,II and V were bigger than those in their counterpart varietal eco-regions,while the pubescence density did not show relationship with their geographic sources.Significantly positive correlations were observed among pubescence angle on leaf petiole,pubescence angle and length on leaf blade,while significant negative correlation was detected between pubescence density and length on leaf blade.The pubescence density and length were significantly different between sharp and blunt pubescence tip,those with sharp pubescence tip had more and shorter pubescence.Two indicators of resistance to bean pyralid,rolled leaflet number(RLN)and rolled leaflet percentage(RLP),were significantly positively correlated with pubescence angle,length on leaf blade,angle on petiole and significantly negatively correlated with pubescence density on leaf blade,but no correlation with pubescence tip shape was observed.Among which,the correlation between pubescence angle on leaf blade and resistance to bean pyralid was the highest,thus small pubescence angle on leaf blade was the most important resistance characteristic.