Studies On Function Of Polyamines During The Initiation And Differentiation Of Male And Female Buds In Walnut

Walnut is originated from our country. Because of its nutritive value of kernel, delicious flavor, and diversified utilizations, walnut has been one of the four famous nuts on the world. However, its lower yields and poor qualities leaded to low economic revenue. One of the important reasons is the excessive consumption of nutritional substances caused by superabundant male flowers, which greatly deteriorate differentiation and development of female flowers and thus reduce the yields and qualities. Functionary mechanisms of polyamines are studied during the initiation and differentiation of male and female buds of walnut by means of both field investigation and laboratory work. The present studies are beneficial to popularize chemical control techniques. The main results are as follows:1. The period of physiological differentiation of early-bearing varieties, such as Liaoning-1, ranges from 3 to 6 weeks after cease of medium and short branches (Jun.2~Jun.23) in Zoumayi town Laiyuan county. The period of physiological differentiation Lasts 4 weeks.2. The treatments with either 1X 10~3~1 X 10~4 mol-l/'put or 1 X 10~3~1 X 10'" mol-L^spd could markedly raise the ratio of floral sexuality of early-bearing walnut (Liaoning-1 and Zhonglin-5) during the period of physiological differentiation of male and female flower buds. The treatments could both promote female and restrain male differentiation. And the effects descend as the reduction of treatment concentration. The treatments with1 X 10 3~1 X 1CT4 mol-L"1 MGBG could markedly reduce the ratio of female flower buds.3. The level of endogenous polyamines (Put, Spd,Spm) in mixed buds of earh-bearing varieties (Liaoning-1,Zhonglin-5) change markedly during the period of female flower buds initiation. The contents of endogenous polyamines in mixed buds are higher than in male buds. Larger amount of endogenous50polyamines are required in differentiation and development of female buds compared with male buds. Also the level of endogenous polyamines (Put, Spd, Spin) in leaves of early-bearing varieties (Liaoning-l,Zhonglin-5) change markedly during the period of female flower buds initiation.4. Spraying with 1 X 10~3~1 X 10"" mol-L 'put or 1 X 10~3~1 X 10"4 mol-L"'Spd could promote synthesis of endogenous polyamines (Put,Spd,Spm). Endogenous Put and Spd levels are affected by all treatments at earlier time, while Spm at later time. And their effects could maintain for a period of time. Exogenous MGBG at 1 X 10~3~1 X 10"" mol-l/'L could markedly reduce the level of endogenous Put and Spd. Treatments at higher are more effective than those at lower concentration.5. The GA3 content in the leaves of Liaoninr-ldeclines during the period of female buds physiological differentiation and remains lower level. The changing trends of ZT-, IAA and ABA contents are similar, which increase first, then decrease and increase again. Higher level of ZT/GA3 and (ZT+ABA) /GA3 are found. Exogenous 1 X 10~3 mol-l/'Put or 1 X 10"4~1 X 10~3 mol-L^Spd could markedly decrease the contents of endogenous GA3 and IAA, while increase the contents of endogenous ZT and ABA. Also those treatments could markedly increase the levels of ZT/GA3 and (ZT+ABA)/GA3. The treatment with 1 X 10"3 mol-L 'MGBG could markedly decrease the level of endogenous ZT and increase the level of endogenous GA3.6. As for mixed buds and male buds of early-bearing walnut (Liaoning-1 and Zhonglin-5) the contents of soluble sugar and starch change from higher to lower levels. Contents of amino acid rise gradually. Contents of protein ascend earlier and descend later. All the changes mentioned above take place from Apr.5 to Apr.26. Similar changing pattern of contents of soluble sugar > amino acid and protein is found both in Liaoning-1 (male-earlier type varieties) and Zhonglin-5 (female-earlier type varieties). But the extent is different. Exogenous Put> Spd could markedly enhance contents of soluble sugar > starch> amino...