The Basic Vegetative Phase and Photoperiod Sensitivity Index as the Major Criteria for Indigenous Upland Rice Production in Thailand under Unpredictable Conditions

Indigenous upland rice (Oryza sativa L.) is an important staple food for people. The productivity of generally lower than lowland since crop yield depends on the amount rainfall. Climate change a major problem in production due to unpredictable flowering time, maturity days, growth duration, and photoperiod sensitivity are determining productivity. Therefore, this study, indigenous germplasm was classified according their flowering-related traits basic vegetative phase (BVP), index (PSI), grain (GY), components. results reveal that BVP ranges from 12 76 days (mainly less 30 days) while PSI −0.14 0.89. Classification three groups based PSI: 24 insensitivities (G1; = −0.14–0.30), 214 weakly sensitive (G2; 0.31–0.70), 63 strongly (G3; 0.71–0.89). Grain showed different correlations with day (DTF), PSI, each group. suggest selection criteria were not only GY DTF but also BVP. new ideotypes under conditions such as rainfall light duration (PSI range 0.30–0.60), low (20–30 days), 105 DTF, ULR189, ULR039, ULR036, ULR403, ULR364, ULR342, ULR245 genotypes.