Germination characteristics of the grass weed Digitaria nuda (Schumach.)

Abstract

The effect of various pre-treatments and their interaction with temperature on cumulative percentage and the rate of germination were evaluated for Digitaria nuda. Stored and fresh seeds were pre-treated with either 0.02M KNO3, soaked in water for 24h (priming), sterilized with 0.5% NaOCl or heat treated at 60°C. Seeds were germinated at constant temperatures of 25 and 30°C and fluctuating temperature regimes of 25/10 and 30/15°C. The effect of pre-chilling on germination of stored and fresh seed was evaluated at 30/15°C, and seed emergence in two soil types at different burial depths (0, 0.5, 1, 2, 3, 4, 5 and 6cm) was also determined. The pre-treatment of stored seed with KNO3 resulted in the highest germination percentage (100%), whereas the pre-treatment of fresh seed with water for 24h gave the best germination (99%), at constant temperatures of 25 and 30°C. Pre-chilling of seed increased germination by more than 30%. Emergence from clay loam soil was greater compared with the emergence from sandy loam soil. Total seedling emergence decreased exponentially with increasing burial depths with only 5% of seed germinating from a burial depth of 6cm. Results from this study showed that germination requirements are species specific and knowledge of factors influencing germination and emergence of grass weed seed can assist in predicting flushes in emergence allowing producers to implement control practices more effectively.