ROOT RESPONSE OF SOME SELECTED RICE VARIETIES TO SOIL MOISTURE STRESS AT DIFFERENT PHENOLOGICAL STAGES

Physiological adjustment in plant root system is a determinant for survival and crop productivity in situation of moisture stress. A screen house experiment was conducted to access response of rice roots to moisture stress. Thirteen  varieties of rice comprising six NERICAs, WAB 56-104, CG 14, ART26-3-1-B, AC 103549, MOROBEREKAN, ART19-25-1-B and a local check (OFADA) were subjected to twenty-day moisture stress once at  each phenological stage. Results indicated that root growth generally showed preference over shoot growth. Moisture stress did not affect root volume (RV), deep root numbers (DRN), root dry weight (RDW) and root depth (RD) of all the rice varieties at reproductive stage. CG14 however recorded 67.6% increase in RD at this stage while NERICA 3, CG14 and OFADA recorded an increase in root depth: shoot length. At vegetative and grain filling stages, RV, DRN, RDW, RD, and RMC were significantly (p< 0.05) increased by moisture stress in most rice varieties. NERICA2, NERICA7, ART26-3-1-B, MOROBEREKAN and WAB56-104 however recorded 54%, 76.5%, 72.7%, 57.1%, and 56.3% significant reduction in DRN respectively at vegetative stage. Correlation analysis showed that plant height, leaf area, and number of tillers depend highly on, RD, RV, RDW and deep root weight. Therefore, attention should be focused on these parameters in selection for moisture stress tolerance in rice.