RESPONSE OF SELECTED GRAIN SORGHUM LINES TO WATER STRESS

Abstract

Sorghum (S. bicolor (L.) Moench) is an important cereal crop in drier areas of the world where drought is a major cause of low yields. Drought can occur at any stage of growth of sorghum in the field. It is characterized by low rainfall and high evapotranspiration rate that leads to water stress in plants. The objective of this study was to determine response of twelve selected sorghum lines to water stress at various stages of growth and development. Screening was carried out on seed imbibition rates, activity of starch degrading enzymes, germination, selected isozymes, and assessment of pre- and post-flowering water stress tolerance in the green house using potted and field grown plants. The sorghum lines which showed the highest imbibition rates and high percentage germination under water stress was MCSR I10, a short duration to total germination under water stress was recorded in MCSR T30 and Gadam. The lines with the longest seedling radicle lengths were MCSR T28, MCSR O2 and MCSR I10. The lines with the highest starch degrading enzyme activity included MCSR O2 and Gadam. The sorghum lines with shortest time to panicle emergence under the pre-flowering water stress included MCSR G2 and MCSR C1, and lines with the lowest percentage panicle weight reduction under water stress included MCSR N4, MCSR G2 and MCSR T28. Under the post-flowering water stress, the lines with the highest total chlorophyll concentration included MCSR D1b, MCSR C1, MCSR G2 and MCSR N4; lines with the lowest percentage in leaf senescence in the field under post flowering stress were MCSR T30, MCSR T28, MCSR I10 and MCSR D1b and sorghum lines with the highest grain yield in the field were MCSR F14a, Gadam, MCSR T28 and MCSR A11. The sorghum lines identified as tolerant to moisture stress during germination included MCSR O2, MCSR I10 and Gadam. The lines which had normal growth, with early panicle emergence and low number of nodal tillers under pre-flowering water stress included MCSR N4, MCSR G2 and MCSRT28. The identified sorghum lines Gadam, MCSR T28 and MCSR G2 can be adopted for planting in dry areas. The lines recommended for use to develop drought tolerant high yielding varieties includes MCSR C1, MCSR T30, MCSRD1b, MCSR N4 and MCSR F14a. These lines need to be tested extensively in the dry areas of the country to confirm their potential for high productivity in arid and semi-arid lands.