我们在依阿华州Ames附近的田间,用100、162公升的容器种植大豆[Glyeine Max (L.,)merr.‘Corsoy’],测定其一个吸水周期内根长(RL)和叶面积(LA)的比值对蒸腾强度及叶片水势的影响。 Olarion粘壤表土(典型的Hapludoll)上,以两种肥力水平配合两种灌溉处理,其RL/LA的比值各有差异。旱周期开始时由于两种容器的大小不同,它们的贮水量是不同的。容器内茎杆周围加上覆盖,以防水分蒸发。蒸腾强度,以一定时间内的容器总重之差来计算。以植株顶端小叶的长、宽计算几天内的叶面积,并以压力室法测定叶水势。收获时测定根长。容器中的总蒸发量(厘米~3/日)随叶面积的增加而直线上升,而蒸腾强度(厘米~3/厘米~2/日)随土壤含水量的降低而直线下降。但在任何含水量情况下,根长对蒸腾强度的影响并不显著(P=0.95)。当特殊处理的RL/LA比值增加时,每米根的吸水率相对的降低。土壤含水量相同时,植株的总根长与每米根的吸水率之间的反比关系,使植株维持稳定的叶水势(不考虑RL/LA的比值)。 We planted soybean [Glyeine Max (L.,) merr.’Corsoy ’] in a 100,162-liter container in a field near Ames, Iowa and measured root length (RL) and leaf area LA) ratio on transpiration and leaf water potential. Olarion loam topsoil (typical Hapludoll), with two fertility levels with the two irrigation treatments, the RL / LA ratio of each difference. Due to the different sizes of the two containers, their storage capacity is different at the beginning of the drought cycle. Cover the stem around the container to prevent moisture from evaporating. Transpiration intensity, in a certain period of time to calculate the difference between the total weight of the container. The leaf area in a few days was calculated from the length and breadth of the leaflets at the top of the plant, and the leaf water potential was measured by the pressure chamber method. Root length measured at harvest. The total evaporation (cm ~ 3 / day) in the container increased linearly with the increase of leaf area, while the transpiration intensity (cm ~ 3 / cm ~ 2 / day) decreased linearly with the decrease of soil water content. However, the effect of root length on transpiration intensity was not significant at any water content (P = 0.95). When the RL / LA ratio of special treatment increases, the water absorption rate per meter decreases. The inverse relationship between the total root length of the plant and the water absorption rate per meter rooted at the same soil water content allowed the plant to maintain a stable leaf water potential regardless of the RL / LA ratio.