DIFFERENCES OF ROOT MORPHOLOGY AND PHYSIOLOGICAL CHARACTERISTICS BETWEEN TWO RAPE GENOTYPES WITH DEFFERENT P EFFICIENCY1

The two rape ( Brassica napus L) genotype with different P-efficiency (HB:higer P-efficiency, SH:lower P-efficiency) were selected from 32 rape cultivas Further studies were carried out to the ability of P absorption; the root morphology such as root/shoot ratio, root length, root volume, root surface area and active absorb surface area; the physiological characteristic such as root membrane permeability, P-efflux rate and kinetic parameters between two rape genotype under P-deficiency and P-adequate conditions The results showed that HB can take in more P from soil than SH The reason was that when P was deficient, HB maintained higher ratio of root to shoot, bigger root system, larger root surface area, higher root activity, stronger affinity to P, so it's uptake efficiency was higher; meanwhile, its root cell membrane permeability and P efflux rate decreased, so the net uptake rate was higher Under the P adequate conditions there was very little difference between two genotype of rape in ability to P absorption