Root and Shoot Response of Six Cotton Cultivars to Water Management

J. Keino, C.A. Beyrouty, and D.M. Oosterhuis


Water availability plays a major role in crop productivity. Crop yield and biomass accumulation is proportional to water moving through the plant via the root system. This study was undertaken to evaluate root and shoot growth response of six cotton (Gossypium hirsutum L.) cultivars to water stress. The cultivars, representing three maturities (Early: DP20 and DES 119; Medium: DP51 and DP 5415; Late: DP 90 and LA 887), were planted on a Captina silt loam (fine-silty, siliceous, mesic Typic Fragiudult) at the Main Arkansas Agricultural Experiment Station in Fayetteville, Arkansas. The field was divided into two sections, irrigated and non-irrigated treatments. Irrigation was applied when soil water potentials dropped below -0.05 MPa indicated with tensiometers placed at the 30-cm depth. Physiological and growth parameters were measured at six stages of cotton development (square (46 days after planting (DAP), square (56 DAP), first flower (72 DAP), peak flower (84 DAP), boll development (106 DAP), and physiological maturity (154 DAP)). Root growth was measured non-destructively using a minirhizotron. Total root length measured to the 60 cm soil depth and root length density (RLD) significantly increased with days after planting until a maximum was reached at boll development. Non-irrigated cotton had a mean root length of 145 cm while irrigated cotton had a mean of 80 cm. Only non-irrigated cotton showed cultivar differences within maturity groups in RLD and these differences depended on DAP. At different times throughout the season non-irrigated DP20, DP51, and LA887 had the lowest RLD's within their respective maturity groups. Maturity differences in total, stem, leaf and boll dry weights were observed in the irrigated treatments. The late maturing cultivars generally produced greater dry weights than the early or medium maturing cultivars. Dry weights maximized at peak flowering for cotton grown under both water management treatments. Leaf area index increased drastically with time until peak flower for all irrigated and non-irrigated cultivars after which time increases in LAI were measured only for the late maturing irrigated cultivars. Neither cultivar or maturity group affected seed cotton yields. Irrigated cotton produced 480 kg ha-1 more estimated seed cotton than non-irrigated cotton. These first year results suggest that cultivars express large differences in root length distribution under water stress. Thus, deep rooting cotton cultivars should be selected within environments where water is limiting. This study will be repeated for several growing seasons to further evaluate the significance of water management on root growth and yield.

Reprinted from Proceedings of the 1994 Beltwide Cotton Conferences pg. 1576
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998