【作者】 韩天富；

【导师】 盖钧镒；

【作者基本信息】 南京农业大学 ， 作物遗传育种学， 1997， 博士

【摘要】 本报告在前人和笔者已有工作的基础上,进一步研究了大豆开花后光周期反应的证据和品种间的差异,并从内源植物激素入手,探讨了开花后光周期反应的生理机制,主要结果总结如下: 1.晚熟大豆品种自贡冬豆的光周期反应存在于出苗至成熟的全过程。在摘除花荚的条件下光周期仍可调控大豆叶片的衰老。试验结果显示,分别在初花(R1)、结荚初期(R3)和鼓粒初期(R5)将自贡冬豆从12h短日照下移至18h长日照下,均使以后的发育进程延迟,并使农艺性状和化学品质发生相应变化;分别在出苗(VE)至第一三出复叶展开(V2)、第一三出复叶展开至初花、初花至完熟(R8)、结荚初期至完熟,鼓粒初期至完熟、鼓粒末期(R6)至完热进行12h短日处理和15h长日处理,发现短日处理的开花期或成熟期明显提前。在摘除花荚条件下,短日照有明显加快大豆叶片衰老的作用,作用大小与品种所属的熟期组有关。文中提出,晚熟大豆品种开花后置长日照下营养生长恢复的现象是长日照直接作用的结果。 2.发现了大豆的花逆转和花序逆转现象,提出了整株逆转的新概念。晚熟大豆品种自贡冬豆出苗后进行8～10d短日照(12h)处理,尔后置长日照(>15h)下,可诱导顶端花序的部分产生,但花序的上部因短日照后进行的长光照处理而形成茎,花序中部少数花芽原基转而分化营养芽。这是长光照诱导的花逆转和花序逆转现象在大豆中的首次发现。已正常开花的自贡冬豆植株转移至长日照下时,愿有花荚大部分脱落,不定芽大量发生,恢复到以营养生长为主的状态。本文将此种现象称为整株逆转(overall reversion)—植物开花逆转现象的一种新类型。大豆开花逆转现象的发现,对于研究大豆个体发育规律和结荚习性的形成具有一定意义,并可望建立植物光周期反应机制研究的实验材料新系统。 3.比较了不同生态类型大豆品种开花前和开花后的光周期反应敏感性。选用中国大豆主要生态区的代表品种12个,在南京春播,通过人工光照处理,比较了各类型品种开花前和开花后的光周期反应敏感性。结果表明,12h短光照处理使所有品种的开花期显著提前(P<0.01),开花后进行短日照处理,使除早熟品种东农36和泰兴黑豆以外的其它品种的成熟期显著提前(P<0.01)。在试验条件下,南方夏大豆品种开花后光周期反应比开花前更加敏感,其它类型品种开花前光周期反应比开花后敏感。相关分析结果表明,大豆开花前和开花后光周期反应敏感性,与自然光照下相应发育时期的长度正相关,较长的前期有利于单株粒数和粒重的提高,较长的后期对提高百粒重有利。讨论了大豆品种开花前、开花后光周期反应敏感性与原产地日照长度及其它环境因子的关系。 4.大豆品种的生育期结构与开花前、开花后光周期反应敏感性有密切关系。分别选用成熟期相近、开花期不同及开花期相近、成熟期不同的南方春、夏大豆品种、研究了生育更多还原

【Abstract】 Upon the former works of other researchers and the author, the evidences, varietal differences and physiological mechanism, especially the roles of endogenous hormones, of post-flowering photoperiod responses in soybean, were further studied in this report. The results were summarized as follows:1. The photoperiod responses of late soybean variety Zigongdongdou held in the full process from emergence to maturation, and photoperiod could regulate leaf senescence even the plants were depodded. The results showed that all transfers from short. days’(SD, 12h) to long days (LD, 18h), started from R1 (beginning bloom), R3 (beginning pod) and R5 (beginning seed), respectively, hastened the development and changed the agronomic characters of plants and chemical composition of seeds. SD hastening effects on flowering or maturation were also found in the photoperiod treatments conducted at the stages from VE (emergence) to V2 (completely unrolling of 1st trifoliate leaf), V2 to Rl, Rl to R8 (full maturity), R3 to R8, R5 to R8 and R6.(full seed) to R8. In the depodded plants, SD hastened senescence of leaves and the effect was related to the Maturity Groups of the varieties. It was proposed that the reversion of flowering plants to vegetative growth, when transferred to LD condition, was directly caused by the long photoperiod. \.2.The reversions of flower and inflorescence (raceme) were discovered and a new concept (overall reversion) of flowering reversion was proposed. Seedlings of a late-maturing soybean variety, Zigongdongdou (ZGDD), were treated with 8 to 10 SD of 12h immediately after the emergence, and then transferred to long LD (>15h). Terminal inflorescence (raceme) could be induced by SD, but the upper part of the inflorescence became stem, and a few floral primordia in the middle part of the inflorescence reversed to differentiate vegetative buds, because of the following LD after the SD induction. The phenomena mentioned above were the Ll)-induced inflorescence reversion and flower reversion in soybean plant. If the normal flowering plants of ZGDD were transferred to LD, the existed flowers and pods fell, fewer new flowers developed and the plants returned to vigorous vegetative growth. This phenomenon was designated by the concept of overall reversion, a new type of flowering reversion in plants. The discovery of flowering reversion is valuable in the study of pod bearing habit and ontogeny of soybean plants, and will be helpful to establish a new system of experimental material in the study of photoperiod responses of plants.3. The sensitivity of pre- and post-flowering photoperiod responses indifferent ecotypes of Chinese soybean were compared. 12 representative varieties collected from main ecological regions in China were sown in spring in Nanjing and different, photoperiod treatments were carried out to compare pre- and post-flowering photoperiod response of the various ecotypes. The results indicated that theflowering of all varieties was highly hastened by SD (12h), and the maturation was evidently hastened (P<0. 01), too, in 10 of 12 varieties, except 2 early ones of Dongnong.36 and Taixingheidou. Under the condition of this experiment, post-flowering photoperiod response was more sensitive than pre-flowering response in summer-sown soybean varieties , other ecotypes responded more sensitively before flowering than after flowering. The correlation analysis showed that the sensitivity of photoperiod responses before and after flowering was positively correlated to the lengths of corresponding developmental stages in natural daylength. Longer vegetative period was beneficial to the increase of seed number and seed yield per plant, and longer reproductive period was beneficial to the increase of lOOseed weight. The relationship between the sensitivity of pre- and post-flowering photoperiod responses and daylength and other environmental factors was discussed.4. It was found that the growth period structure (GPS, the ratio of the length of reproductive period to that of vegetative period) of soybean varieties w; , closely related to pre- and post-flowering photoperiod response sensitivity (PRS , In the study, the relationship between GPS and pre- and post-flowering RPS of varieties with similar maturity dates and different flowering dates or the ones with similar flowering dates and difl rent maturity dates were studied. The results showed that the length of pre- or post-flowering period in natural photoperiod was positively correlated to PRS in the stages. Among the varieties with similar flowering dates, the length of reproductive period ^was positively correlated to the maturation hastening rate (MHR). Some varieties did not accord with the above rule, demonstrating that the relationship was complicated. When maturing at the similar dates, the spring- or summer-sown varieties with longer vegetative period had more seeds and higher yield per plant, and the ones with longer reproductive period had higher 100-seed weight and lower yield. Among the summer-sown varieties with similar flowering dates, the ones with longer reproductive period had higher 100-seed weight. In spring-sown varieties, no significant correlation between the reproductive period and agronomic characters was found.5. The endogenous hormones played important roles in pre- and post-flowering photoperiod responses of soybean. The results showed that ABA was higher in SD than in LD but GAlt3, GAi*s/ABA and DHZR were lower in SD, IAA did not change greatly. In SD, GAi.:? was negatively correlated with IAA and was positively correlated with ABA. IAA was negatively correlated with DHZR in LD. DHZR was positively correlated with ABA both in SD and LD. The changes mentioned above had the similar trend in different varieties or developmental stages. We proposed that, in the development of soybean, the total amount of promoting substances retained quite stable by their opposite changes of corresponding hormones, and a relative balance between growth promoting substances and growth inhibitors maintained. The hormonal balance, especially the ratio of GA to ABA, played important roles inphotoperiod responses of soybean.6. The changes of endogenous hormones in photoperiod aftei—effect, LD-induced i nf I orescence revers i on, photoper i od response of depodded p! ants and the hormona I role in photoperiod regulation on source-sink relation were studied. Pre-flowering SD treatment hastened post-flowering development of super-early soybean variety Dongnong 36 and decreased the contents of ABA and ZRr. in leaves after flowering. When the seedlings of Zigongdongdou were induced by SD conducted at seedling (VE ~ V2) and then transferred to LD, the content of 1AA in leaves at V2 and latter stages was higher and ABA was lower in the leaves of SD-induced plants than that, grown continuously under 15h. It was proposed that the amount of hormones could be regulated with negative feed-back after SD treatment. In the depodded plants, SD increased the contents of ABA and IAA in the leaves. The ratio of hormonal contents in leaves to that in filling seeds were lower in SD than that, in LD. The increase of 100-seed weight in’SD may be related to more partitioning of hormones in the filling seeds’ than in leaves. Applications of GA? in SD , PP333, S?<w and ABA in LD did not greatly influence the developmental rate of soybean plants. The reasons of hormonal content fluctuation in years and locations, possible thermo-photoperiod interaction on hormones and the complication of hormonal roles in soybean development and chemical regulation were discussed.7. It was found that post-flowering photoperiod responses existed in other crops besides soybean. The results showed that LDP and SDP .^till responded oppositely to photoperiod after flowering. Post-flowering SD treatment evidently delayed the seed maturation of sugar beet and slightly delayed that of rapeseed. Tuber number, weight per tuber and yield per plant of potato were increased by post-flowering SD treatment. Maturity of rice was hastened by SD after flowering. SD slightly increased seed-cotton yield, but did not influence the development, of cotton plant. Corn varieties in this experiment were insensitive to post-flowering photoperiod. It was concluded that post-flowering photoperiod responses existed in many other plants besides soybean, and there was broad diversity among species and genotypes.更多还原