To explore the groundwater recharge rate and soybean growth dynamics under different groundwater depths, we conducted a field experiment with four groundwater depth treatments (1 m, D1; 2 m, D2; 3 m, D3; 4 m, D4) through the groundwater simulation system in 2021 and 2022 and explored the relationships between groundwater depth and groundwater recharge, irrigation, growth dynamics of soybean plants, and yield. We used the Logistic regression model to simulate the dynamics of soybean growth indices, including plant height, leaf area index, and dry matter accumulation. The results showed that compared with D1 treatment, the amount of groundwater recharge under D2, D3, and D4 treatments decreased by 81.1%, 96.8%, 97.5% and 80.7%, 96.7%, 97.3% in the two years, respectively. The groundwater in D1 treatment could meet water needs of soybean throughout the whole growth period, except that irrigation was needed in the sowing stage. The amount of irrigation under D1 treatment was decreased by 91.7%, 93.0%, 94.2%, and 90.9%, 92.9%, 94.0% in the two years, respectively, compared with D2, D3, D4 treatments. Among the four treatments, D1 treatment took the shortest time for entering the rapid growth stage and reach the maximum growth rate, which had the highest maximum growth rate. At the mature stage of soybean, the dry matter distribution ratio of stem in D1 treatment was the highest. D1 treatment promoted the translocation of post-flowering assimilates in soybean, and its post-flowering assimilate contribution to seeds increased by 15.5%, 16.2%, 32.6% and 45.5%, 48.7%, 63.3% in the two years, respectively, compared with D2, D3, D4 treatments. D1 treatment had the highest plant height, leaf area index, and dry matter accumulation, follo-wed by D4 treatment, while D3 treatment had the lowest. Soybean yield, number of pods per plant, number of grains per plant, and 100-grain weight all decreased and then increased with increasing groundwater depth, following an order of D1>D4>D2>D3. Soybean yield was significantly positively correlated with groundwater recharge, which was positively correlated with plant height, leaf area index, and dry matter accumulation. Our results indicated that the D1 treatment with adequate groundwater recharge increased plant height, leaf area index, and dry matter accumulation, coordinated the distribution and translocation of dry matter among all plant parts in the late soybean growth period, and ultimately achieved the highest yield. When groundwater depth was deep (D4), groundwater recharge was small. In such case, the growth and development status and yield of soybean could also reach a high level if there was sufficient water supply.
为探明不同地下水埋深条件下地下水补给状况及大豆生长动态变化,于2021和2022年利用地下水位自动控制系统开展了4个地下水埋深处理(1 m,D1;2 m,D2;3 m,D3;4 m,D4)的栽培试验,探讨地下水补给量、灌溉用水量、植株生长动态和产量与地下水埋深的关系,并采用Logistic模型对株高、叶面积指数和干物质积累等生长动态进行模拟分析。结果表明: 与D1处理相比,D2、D3、D4处理地下水补给量在2年中分别降低81.1%、96.8%、97.5%和80.7%、96.7%、97.3%;D1处理大豆仅在播种时灌溉1次,其后整个生育期依靠地下水补给就可以满足生长发育的水分需求,其灌溉用水量在2年中分别较D2、D3、D4处理减少91.7%、93.0%、94.2%和90.9%、92.9%、94.0%。4个处理中,D1处理株高、叶面积指数和干物质积累进入快速生长期和达到最大生长速率的时间最短,最大增长速率最大,成熟期茎干物质分配比例最大,并促进了植株花后同化物的转运,其花后同化物对籽粒的贡献率在2年中分别较D2、D3、D4处理提高15.5%、16.2%、32.6%和45.5%、48.7%、63.3%,最终大豆株高、叶面积指数和干物质积累量均最大,D4处理次之,D3处理处于最低水平。大豆产量和单株荚数、单株粒数、百粒重均随地下水埋深的增加先减小后增大,具体表现为D1>D4>D2>D3;大豆产量与地下水补给量呈极显著正相关,与株高、叶面积指数和干物质积累量均呈不同程度的正相关。综上,D1处理地下水补给充足,提高了大豆株高和叶面积指数,增大了全生育期干物质积累量,并协调生育后期植株各部分干物质的分配和转运,产量最高;当地下水埋深较大时(D4),地下水补给不济,若有充足的水分供给,大豆的生长发育和产量也能达到较高水平。.
Keywords: groundwater depth; groundwater recharge; growth dynamic; soybean; yield.