COMPARISON OF SEED-QUALITY INDEXES RESULTING FROM SINGLE-SEED ELECTROCONDUCTIVITY MEASUREMENTS

Five seed-quality indices based on individual seed electrolyte leakage tests were evaluated. Zea mays L. seeds were soaked for 6 hours, and individual seed leachate conductivity values were obtained. A total of 100 cells were scanned, one seed per cell, at 5-minute intervals for the first 30 minutes, followed by 15-minute intervals for the remainin g 330 minutes. Seeds were allowed to dry for 5 to 7 days at room tempe rature and then were tested for germinability at 25C for 7 days. Radic le lengths were measured after 72 hours. The Richards function was fit ted to cumulative frequency distributions of muAmps to obtain internal slope (IS), mean muAmp, and median muAmp values for each scan. Initia l leach rate (ILR) was estimated after fitting hyperbolic functions to muAmp vs. soak time data. Average leach rate (ALR) was also derived f rom fitting the Richards function to muAmp vs. soak time data. Linear regression of seed quality on IS, mean, and median pAmp values after 5 hours of imbibition yielded r2 values of 0.91, 0.81, and 0.86 for pre dicting viability and 0.56,0.46,0.52 for predicting radicle length. Th us, IS was the best seed quality predictor, followed closely by median and mean muAmp values. ILR and ALR were not correlated with seed qual ity.