Effects of Soil Water Tension on the Emergence and Growth of Cotton Seedlings
1971
Jensen, R. D.
A laboratory study was conducted to determine the effects of soil water tension on the rate and percentage of emergence and the vigor of cotton (Gossypium hirsutum L.) seedlings in a soil environment. Pressure plate apparatus was used to bring the soil to the tensions desired. One hundred seeds were planted equal distance apart in a silt loam soil at a depth of 2.5 cm in a 30-cm-diameter enameled pan. The soil was compressed around the seeds to a bulk density of about 1.1 g/cm³. The pan was enclosed in a transparent plastic bag and placed in a constant temperature chamber at 25 C. The number, height, and a description of the appearance of the seedlings which had emerged were recorded daily for 4 weeks. Total emergence was not affected by changes in soil water tension between 1/3 bar and 3 bars. Emergence at 4 bars tension was significantly less than at lower tensions. The number of seedlings which emerged decreased slowly as the tension increased from 4 to 7.5 bars. A sharp decrease was observed in the emergence at a tension of 8 bars. No emergence occurred at tensions greater than 12 bars. The time required for emergence and the growth rate of seedlings was not significantly affected by changes in tension from 1/3 to 1 bar. The rate of emergence and the growth rate progressively decreased as tension increased from 2 to 4 bars. Thereafter, as tension increased, time requird for emergence increased rapidly and rate of growth simultaneously decreased sharply.
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