Response of Selected Soybean Cultivars to Soil Moisture Deficit1
- E. A. Brown,
- C. E. Caviness and
- D. A. Brown2
Extensive research has been conducted on effects of moisture stress on growth and development of soybean [Glycine max (L.) Merr.] but information is limited on the response of determinate cultivars to moisture stress initiated at different growth stages. Moisture is a major factor limiting yield in most areas where soybeans are grown. Moisture stress experiments were conducted under field conditions using four determinate soybean cultivars of Group VI maturity, ‘Davis’, ‘Lee 74’, ‘Sohoma’, and ‘Centennial’. The experiments were conducted in 1980 and 1981 on a Captina silt loam (fine-silty mixed, mesic Typic Fragiudult) at Fayetteville, AR. These experiments consisted of two moisture stress treatments which were initiated at the R2 and R4 growth stages and a control which was irrigated as needed throughout the season. Measurements were made on both roots and aboveground plant parts. When a moisture deficit was initiated by placing black plastic over the plots at either R2 or R4, seed yield was significantly reduced both years. A moisture deficit following application of plastic at R2 reduced yield more than at R4 in 1981, but the reverse was found in 1980, an extremely dry year. A moisture deficit initiated at R4 significantly reduced seed size and seed number both years whereas seed size was not significantly reduced either year by deficits initiated at R2. Sohoma produced significantly larger seeds than the other three cultivars when plants were moisture stressed at R4. No significant cultivar X moisture stress interactions involving seed yield were observed in either year; however, there was a definite trend for seed yields of Sohoma to be reduced less by moisture deficits initiated at stage R4 in both 1980 and 1981. Percent flower and pod shedding did not appear to be affected to any great extent by the moisture stress treatments in either year. In general, as the total number of flowers and pods increased, the number of flowers and pods shed increased proportionally. There were about four times as many roots under the row as were present in the furrow middles in both years. Also, a moisture deficit restricted root growth under the row in the upper portion of the profile, but increased it in the lower portion in the dry year of 1980.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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