Relationship between seed structure and water absorption in adzuki bean ( Vigna angularis) and related species.

(1)在供试小豆及其近缘种中，菜豆(Vigna Umellata)和绿豆(V.Radiata)的吸水速度比小豆快，黑豆(V.mungo)和小豆(V.angularis var.)日本)产生33%至56%的坚硬种子。然而，所有品种的初始入水部位基本上都是球茎，这是一个位于种脐一端的非常小的凸起。(2)从91个品种和品系的种子吸水试验结果来看，小豆种子的初始吸水率差异很大(浸泡4h后，吸水率为2-82%)。虽然这些差异随着时间的推移而变小，但种子的最终吸水率(浸种36h后)与初始含水量、种子重量和成熟度呈正相关(r分别为0.456、0.368和0.598)。(3)用常规显微镜观察方法定期观察小豆种子的形态。在开花后9天，球果的大小已达90%。在完成的种子柄栅栏层下面是含有木质素样物质的薄壁细胞，表面中心有一条中缝。(4)成熟时收获的植株用手工和小型脱粒机脱粒，操作时间不同。然后，对种子进行吸水率测试，并用扫描电子显微镜观察种子的种子柄表面。种子吸收水分的速度越快，对种子的机械冲击越大。这种程度与中缝分离的程度一致。这些结果表明，小豆的吸水率可能受中缝状态的控制。

(1) Of adzuki bean and related species tested, rice bean ( Vigna umbellata) and green gram ( V.radiata) absorbed water more quickly than adzuki bean, while black gram ( V.mungo) and Yabutsuru-adzuki ( V.angularis var. nipponensis) produced hard seeds of 33 to 56%. However, a site of initial water entry was confirmed in all species to be essentially strophiole, a very small bulge located near one end of hilum, from data of water absorption tests after sealing strophiole.(2) From the results of water absorption test for adzuki bean seeds of 91 cultivars and lines including foreign materials, the initial water absorption rate varied widely (2-82% after 4h-soaking). Although these differences became small with time, the final water absorption rate (after 36h-soaking) of seeds was positively related to initial water content, seed weight, and maturity (r=0.456^<***>,0.368^<***>, and 0.598^<***>, respectively).(3) Seed morphology of adzuki bean was periodically investigated using a common microscopic observation method. Strophiole reached 90% of its full size at 9 days after flowering. Beneath the palisade layer of completed strophiole were parenchyma cells containing lignin-like substances and a line (raphe) ran in the center of surface.(4) Plants harvested at maturity were threshed by hand and by a small thresher with varied operating times. Then, seeds were tested for water absorption and observed for strophiole surface using a SEM.The stronger mechanical impact on seeds was the faster seeds absorbed water. The extent was consistent with the degree of raphe separation. These findings indicate that water absorption of adzuki bean could be controlled by the state of raphe.