Effects of Temperature and Flooding on Rice Growing in Saline and Alkaline Soil1

Abstract

Abstract‘Bluebelle’ cultivar of Oryza sativa L. was grown in a growth chamber at 4 and 16, 10 and 21, 16 and 27, and 21 and 33C night (10 hr) and day (14 hr) temperatures, respectively. Flood water was applied 12 (early) or 24 (late) days after seedling emergence at 6‐ and 12‐cm depths to seedlings growing in saline, alkaline, and normal Crowley silt loam soil. Plant tops were harvested 53 days after seedling emergence and analyzed for dry matter production and composition of P, K, Mg, Na, Fe, Mn, and Zn. Water samples were collected at the soil‐water interface 1, 2, 5, 7, 8, 9, 10, 11, 14, and 15 days after seedling emergence and analyzed for pH, electrical conductivity, CO3‐, HCO3‐, and C1‐.When temperature was increased, the order of dry matter production by plants growing in the various soils was normal > saline > alkaline. Applying flood water 12 days after seedling emergence caused plants growing in saline and normal soils to produce more dry matter, whereas those growing in alkaline soil produced more dry matter when flooded 24 days after seedling emergence. Varying flood depth did not affect growth.Plants growing on saline and alkaline soils at 21 and 27C were chlorotic and P/Zn was less than 1.0. When temperature was increased to 31C chlorosis disappeared and P/Zn was greater than 1.0; however, the data did not explain the effects of flood time on growth.Bicarbonate level of water above the alkaline soil was higher when flooding was delayed. This suggested young seedlings were more sensitive to HCO3‐ than were older seedlings, since growth was greater with delayed flooding.Flooding saline soil early produced lower EC and Cl‐ values in the water than did late flooding. Thus, plants grew more when flooded early because salinity was lower.