Soybean response to near saturated soil.

English. Tese (Doutorado) - Mississippi State University, Starkville.

English. Increases in soybean productivity have been relatively small compared to other major economic crops. Wet-soil culture, a relatively new technique of growing soybeans under a high controlled water table, has increased soybean production potential under Australian conditions. Therefore, two field experiments during 1985 and 1986 seasons were conducted with U.S. adapted varieties at the Plant Science Research Center, Mississippi State University. The first study had twenty-four varieties from three different maturity groups tested in three soil moisture regimes: wet-soil culture + N, conventional irrigation and dry. The 1985 season showed low performance of soybean plants grown in wet-soil culture compared to conventional irrigation and dry grown beans. Thiswas due to the water table being higher than intended, which resulted in near flooding. Planting of flat beds contributed to this near flooding situation. By planting on elevated beds in 1986, the wet-soil culture outyielded the other two soil moisture regimes due to better water table control. The second study was a combination of two varieties, five rates of N and two times of initiating wet-soil culture. The varieties were Tracy-M and Centennial (Leflore in 1986). Nitrogen was surface applied as urea at five rates. Time of initiating wet-soil culture was V3 and V8 growth stages. The same problem of near flooding occurred in this experiment, as evidenced by stem splitting. This morphological change was not present in 1986. Seed yield was slightly (...)