Soil Water Deficit and Fertilizer Placement Effects on Root Biomass Distribution, Soil Water Extraction, Water Use, Yield, and Yield Components of Soybean [Glycine max (L.) Merr.] Grown in 1-m Rooting Columns

Abstract

Typical small-pot culture systems are not ideal for controlled environment phenotyping for drought tolerance, especially for root-related traits. We grew soybean plants in a greenhouse in 1-m rooting columns filled with amended field soil to test the effects of drought stress on water use, root growth, shoot growth, and yield components. There were three watering treatments, beginning at first flower: watered daily to 100% of the maximum soil water holding capacity (control), 75% (mild drought stress), or 50% (drought stress). We also tested whether applying fertilizer throughout the 1-m soil depth instead of only in the top 30 cm would modify root distribution by depth in the soil profile and thereby affect responses to drought stress. Distributing the fertilizer over the entire 1-m soil depth altered the root biomass distribution and volumetric soil water content profile at first flower, but these effects did not persist to maturity and thus did not enhance drought tolerance. Compared to the control (100%) watering treatment, the 50% watering treatment significantly reduced seed yield by 40%, pod number by 42%, seeds per pod by 3%, shoot dry matter by 48%, root dry matter by 53%, and water use by 52%. Effects of the 75% watering treatment were intermittent between the 50 and 100%. The 50% treatment significantly increased root-to-shoot dry matter ratio by 23%, harvest index by 17%, and water-use efficiency by 7%. Seed size was not affected by either fertilizer or watering treatments. More than 65% of the total root dry matter was distributed in the upper 20 cm of the profile in all watering treatments. However, the two drought stress treatments, especially the mild drought stress, had a greater proportion of root dry matter located in the deeper soil layers. The overall coefficient of variation for seed yield was low at 5.3%, suggesting good repeatability of the treatments. Drought stress imposed in this culture system affected yield components similarly to what is observed in the field, with pod number being the component most strongly affected. This system should be useful for identifying variation among soybean lines for a wide variety of traits related to drought tolerance.

Adaptation of Grain Legumes to Transient Water Deficit in Timor-Leste

“…Water availability in the field can decrease dramatically with extreme high temperatures that increase water evaporation from the soil surface [4]. Water deficit decreases crop growth, development, yield, and yield components of grain legumes [5][6][7]. The extent of the yield reduction depends on the duration and intensity of the stress and varies between species and cultivars and climatic variations, as reported for mungbean, soybean, and grass pea [6][7][8][9][10].…”

“…Water deficit decreases crop growth, development, yield, and yield components of grain legumes [5][6][7]. The extent of the yield reduction depends on the duration and intensity of the stress and varies between species and cultivars and climatic variations, as reported for mungbean, soybean, and grass pea [6][7][8][9][10]. Reduced soil water content to a moderate drought level (60% field capacity) reduced pod and seed numbers and seed yield per plant in mungbean (line 97001) [11].…”

Suitable Fertilizer Application Depth Enhances the Efficient Utilization of Key Resources and Improves Crop Productivity in Rainfed Farmland on the Loess Plateau, China

“…Recent studies have explored various fertilization management practices for improving crop productivity ( Liu et al, 2015 ; Su et al, 2015 ; Gebre and Earl, 2021 ; Zhong et al, 2021 ). In particular, compared with broadcasting or mixing fertilizer, banding fertilizer in the soil can improve the NUE and crop yield in rice ( Liu et al, 2015 ; Zhong et al, 2021 ), rape ( Su et al, 2015 ), soybean ( Gebre and Earl, 2021 ), wheat ( Singh et al, 2005 ), and maize ( Cheng et al, 2020 ; Wu et al, 2021 ). Therefore, banding fertilizer has some advantages for promoting crop production.…”

“…These advantages are mainly due to banding fertilizer improving the availability of nutrients in the crop root zone to promote the growth and function of roots. Banding fertilizer in the root zone is an effective fertilization method and it has attracted much attention from researchers ( Liu et al, 2015 ; Su et al, 2015 ; Gebre and Earl, 2021 ). Su et al (2015) showed that fertilization at soil depths of 10 and 15 cm increased the taproot length and dry weight compared with depths of 0 and 5 cm.…”

Phosphate starvation response precedes abscisic acid response under progressive mild drought in plants

“…However, since soybean is cultivated mostly under rainfed conditions, soybean production is severely constrained by abiotic stresses, particularly drought (5). Even mild drought stress that occurs without obvious outward signs of a stress response such as leaf wilting poses a major threat to soybean productivity (6). Given that strategies to increase arable land area and yield face major obstacles, identifying ways to reduce crop production losses due to mild drought stress is a key goal in attaining global food security.…”