缺磷胁迫对黄瓜体内磷运输及再分配的影响

EFFECT OF P DEFICIENCY ON TRANSLOCATION AND REDISTRIBUTION OF PHOSPHATE IN INTACT PLANTS OF CUCUMBER

本研究用营养液培养法定量地测定并计算了在正常供磷及缺磷后不同时间黄瓜植株体内磷的分布及再运输。缺磷处理５天后，新生叶和根系中的吸磷量明显增加，分别占植株总吸磷量的３６．１％和１３．５％，而相应的正常供磷植株的新生叶和根系中的吸磷量仅分别占植株总吸磷量的２２．４％和６．３４％，而且缺磷植株根系的生长显著快于供磷的植株。缺磷胁迫１０天后，植株地上部生长受到明显抑制，老叶中的磷通过韧皮部运向新生叶以保证新生器官的生长，使新生叶中磷的浓度比老叶中高４７％，但缺磷植株根系中磷的累积量下降不多。本研究还定量证明了即使在正常供磷条件下，随着生长时间的延长，也有大量的磷由老叶运向新叶。不论缺磷与否，植株新生叶和根中磷的浓度都保持最高，但缺磷和供磷植物体中磷的分配模式不同。

Experimental-based modelling technique (Jeschke & Pate, 1991) was applied to describe quantitatively the uptake, translocation and redistribution of cucumber (Cucumis sativus L.) which was cultured either 0.25 mmol/L H2PO-4or P-free in nutrient solution. 5d after -P treatment, not only relative more P translocated to young leaves (36.1% to total P content in a plant) and root (13.5% to total P content in a plant), but also the growth rate of root was higher than that in +P plants. P content in young leaves and root of +P plants was only 22.4% and 6.34% respectively to total P content in a plant; At 10d after treatment, the growth of shoot was restricted heavily, considerable remobilization of P from older leaves led to young leaves via phloem. The P concentration in young leaves was 47% higher than that in old leaves, and the decrease of P content in root was little. Even in +P plants a large ammount of P in old leaves translocated to young leaves via phloem. Young leaves and root acted as major sinks either in -P plants or +P plants. Translocation and redistribution of phosphate was different in -P plants and +P plants.