Abstract:

Young kiwifruit seedlings（Actinidia deliciosa and A. chinensis）were planted in nutrient solutions aerated with nitrogen. Under root-zone hypoxia stress, the growth and response of endogenous hormones abscisic acid (ABA), indole-acetic acid (IAA), zeatin riboside (ZR), gibberellins (GA3) in kiwifruit seedlings were studied. The results showed that the fresh and dry weight of seedlings treated under hypoxia were less than those of control. Effects of hypoxia stress on A. deliciosa were much slighter than on A. chinensis, which made A. deliciosa perform a better resistance. The ABA contents in A. deliciosa, A. chinensis leaves and roots were enhanced obviously, namely raised by 289.2%, 412.9%, 188.5%, 177.4%, respectively. The IAA contents in A. deliciosa, A. chinensis leaves were raised to the maximum on the 6th day, then reduced but still higher than those of control, namely raised by 87.3%, 61.4%, respectively. Same tendencies happened in the roots of both species, but the peak appeared on the 4th day and differed from that for the leaves. The IAA contents in roots of A. deliciosa, A. chinensis were increased by 90.4%, 59.6%, respectively. The GA3 and ZR contents in A. deliciosa, A. chinensis leaves were decreased by 56.5%, 79.0%, 70.5%, 86.1% correspondingly. The GA₃ and ZR contents in A. deliciosa, A. chinensis in roots were lessened by 33.1%, 55.1%, 46.9%, 71.3% correspondingly. The ratios of IAA/ABA, ZR/ABA, GA3/ABA were also studied and the results of them decreased, which showed that kiwifruit seedlings were obviously inhibited from growing under hypoxia and the resistant ability had an intimate relationship with endogenous hormones.

Key words: kiwifruit, seedlings, hypoxia stress, endogenous hormones