Stay green physiological capacity of drought tolerant maize inbred lines

Stay green is the ability of a plant to maintain photosynthetically functional green leaf area for longer periods, even under excessive water stress. This study was done to establish the physiological capacity of Ugandan drought tolerant maize inbred lines to stay green under water shortage conditions using various stay green physiological determinants. Seventy-six maize inbred lines characterised for drought tolerance by CIMMYT, were planted under a rain out shelter, with a well-watered control (WW) and excessive water-stress treatments applied at six weeks after planting (6 WAP) and eight weeks after planting (8 WAP). The most maintained stay green physiological determinants under excessive water-stress were non-photosynthetic quench (NPQt) and leaf pigmentation per unit leaf area (RC: LAUG) with inbred lines CELQ15028 and CELQ15022 showing the highest maintenance for the two parameters, respectively. The highest level of variation for quantum yield of photosystem II activity (Phi2) and NPQt among inbred lines was at 40 and 60 days after flowering, respectively. Phi2 was negatively correlated to NPQt but positively correlated to the linear electron flow (LEF); while NPQt had a significantly negative correlation with LEF. This study established that these drought tolerant maize inbred lines have moderate stay green physiological capacity, with inbred line CEL15027 performing the best.