东北春玉米不同发育期干旱胁迫对根系生长的影响

分别在玉米拔节期(BJ)和抽雄期(CX)进行水分胁迫试验,利用微根管技术观测不同发育期干旱过程中根分布动态,并利用根分布模型模拟相关参数(d_(50)和d_(95):累积根比例分别为50%和95%的土层深度),对不同干旱胁迫处理的土壤湿度、根系分布及相关参数时空动态特征进行分析。结果表明:水分控制后的土壤湿度在130cm以上基本达到预期干旱效果,即BJ和CX处理在控水时段0~100 cm土层土壤相对湿度都降至40%以下,但深层土壤湿度并未受到水分控制影响;拔节和抽雄期干旱胁迫条件下,根长密度(RLD)最大值分别为2.18±0.89cm·cm~(-3)和2.10±0.47 cm·cm~(-3),所在土壤深度为60 cm,对照(CK)RLD最大值为1.24±0.77 cm·cm~(-3),所在深度为40 cm,CK和BJ处理的RLD在最大值深度以下随土层深度增加而减小,CX处理的RLD在80 cm以下仍保持较大值;BJ和CX比CK的d50分别增大45%和59%,d95分别增大8%和41%,证明玉米根系因干旱胁迫而向深层土壤生长。

Effects of drought stresses during key growth periods on root growth of spring maize in Northeast China

To investigate the effects of drought stress during growing periods on root distribution (RD) of spring maize during the jointing (BJ) and tasseling (CX) stages of maize, the root length densities (RLDs) at different soil depths during the corresponding growth periods were dynamically measured with the minirhizotron method, and the parameters d₅₀ and d₉₅ related to RD representing respectively the soil depths where cumulative root fraction are 50% and 95% were simulated using root distribution model, and then spatio-temporal characteristics of soil relative water contents (SWC), RDs and theirs parameters were analyzed. The results showed that after water stress, actual SWC was basically consistent with the expectant condition though there were some differences between the two. More specifically, the SWC above the soil depth of 130 cm basically achieved the intended result, that is, the SWCs above the soil depth of 100 cm for the BJ and CX treatments were respectively below 40%. Conversely, the SWCs in the deeper soil layers were not impacted by water stress and still kept suitable soil water conditions. In addition, the maximums of RLDs were 1.24±0.77 cm·cm^-3 at the depth of 40 cm for the CK treatment and 2.18±0.89 cm·cm^-3 and 2.10±0.47 cm·cm^-3 at the depth of 60 cm for the BJ and CX treatments, respectively. Below the depth of the maximum RLD, the RLDs for the CK and BJ treatments decreased with the increasin g soil depth and the RLD for CX treatment kept a larger value below the soil depth of 80 cm. Furthermore, the d₅₀, d₉₅ for BJ and CX treatments were 45% and 59%, 8% and 41% larger than those of the CK treatment respectively, which proved that the maize root will grow to deeper soil layers when suffering drought stress relative to normal condition. In conclusion, this study can offer a reference for optimizing the root water uptake parameterization schemes in land surface, ecological and crop growth models.