Effect of excess soil water on the development of Bermuda grass (Cynodon spp.)

ABSTRACT Soil drainage is an important technique in the construction of a sports lawn and information about the sensitivity of the crop to excess water influences the design of the project. Assuming that excess water affects the development of the grass and that the indices SEW30 (Sum of Excess Water above 0.30 m depth) and SDI (Stress-Day Index) are sensitive to the variables of development of the crop, the objective was to identify the sensitivity of Bermuda grass to the excess of water. The experimental design was completely randomized with five treatments and four repetitions. The treatments consisted of groundwater elevations: 0 cm d (at the level of the drains - control); 180 cm d (at 0.20 m from the soil surface); 270 cm d (at 0.15 m from the soil surface); 360 cm d (at 0.10 m from the soil surface); and 450 cm d (at 0.05 m from the soil surface), carried out fortnightly, lasting three days. The variables used to test the treatment were root length, photosynthesis rate, dry mass of roots, stolons, rhizomes, culms and leaves and dry mass of grass clippings. Stress caused by excess water near the soil surface reduced root length, dry mass of culms and leaves, and photosynthesis rate; Bermuda grass was more sensitive to excess water in its initial vegetative stage, which occurs until 42 days after planting; and the photosynthesis rate in the treatment with highest stress level decreased by approximately by 2/3 when compared to the condition of no water table.

摘要 土壤排水是运动场草坪建植中的关键技术，草坪草对积水的敏感性相关信息对该工程的设计具有重要指导意义。本研究假设积水会抑制草坪草生长，且SEW30（0.30米深度以上积水总量，Sum of Excess Water above 0.30 m depth）与SDI（胁迫日指数，Stress-Day Index）这两项指标可响应草坪草生长相关变量，旨在明确狗牙根（Bermuda grass）对积水的敏感性。本实验采用完全随机设计，设置5个处理组与4次重复。各处理组通过调控地下水位高度实现：0 cm d（位于排水管水平位置，即对照组）、180 cm d（距土表0.20米）、270 cm d（距土表0.15米）、360 cm d（距土表0.10米）以及450 cm d（距土表0.05米），处理每两周实施一次，单次持续3天。本研究用于检验处理效应的观测变量包括根长、光合速率、根系干重、匍匐茎干重、根茎干重、茎秆与叶片干重，以及草坪修剪物干重。研究结果表明：近土表面积水引发的胁迫会降低根长、茎秆与叶片干重以及光合速率；狗牙根在种植后42天内的营养生长初期对积水更为敏感；与无地下水位的对照条件相比，胁迫程度最高的处理组光合速率下降幅度约为2/3。