Characteristics on Root Morphology and Root exudation of Soybean in Relation to Phosphorus Efficiency

Soil pot and hydroponic experiments were conducted to compare root morphological features and root exudation characteristics of difference soybean Glycine max (L ) Merrill varieties The results indicated that genetic variation existed among the tested cultivars Under low phosphorus condition, a soybean cultivar, Nanxiong 36 , had relatively higher phosphorus efficiency than the other cultivars used Under phosphorus deficiency, root shoot ratio,tap root length, root total absorbing area and active absorbing area of soybean did not show a clear pattern of variation, hence these parameters should not be considered as specific indices of phosphorus efficiency At low phosphorus availability, soybean exuded higher amount of total acid and H + than at high phosphorus availability At low phosphorus level both total acid and H +exuded by variety Nanxiong 36 were significantly higher than the other cultivars At low phosphorus level the quantity of oxalic acid exuded by soybean roots was in general higher than those at high phosphorus level The quantity of oxalic acid and lactic acid exuded by Nanxiong 36 was relatively higher, which might imply that this cultivar has the genetic potential in solubilizing unavailable phosphorus in the soil, and hence has higher phosphorus efficiency