Radicle Emergence Test Estimates Predictions of Percentage Normal Seedlings in Standard Germination Tests of Aubergine (Solanum melongena L.) Seed Lots

Abstract

An experiment was made to test the potential for radicle emergence (RE), and predict the germination percentage of normal seedlings both at constant (25 °C) and fluctuating (20/30 °C, 16 h/8 h) temperatures for 23 commercially available Thiram treated and untreated aubergine (Solanum melongena L.) seed lots. Frequent counts of RE at 96, 104, 112, 120, 128 and 136 hours in two different temperature regimes (constant and alternating) consistently predicted final normal germination after 14 days. The R² values at fluctuating temperatures (R²=0.69 and 0.88, p < 0.001) were generally higher than those at a constant (R²=0.60-0.63, p < 0.01) temperature. Among the 23 seed lots, nine were Thiram threated. The R² relationship in both temperature regimes were reduced (for Thiram-threated seed lots ranging between R²=0.60-0.79 at 25°C and 20/30°C respectively, and for untreated lots ranging between R²=0.68-0.91 at 25 °C and 20/30°C, respectively). Cumulative germination was slightly higher in the lots kept at fluctuating temperatures than in those kept at a constant temperature. The results showed that the RE test (i.e. 104 h count) can be used to make quick and repeatable predictions of the percentage of normal seedlings in aubergine lots. Moreover it was also significantly related to mean germination time (MGT) values at constant (R²= 0.769, p < 0.001) and alternating temperatures (R²= 0.861, p < 0.001).