The Emergence of Rice (Oryza sativa L.) Genotypes under Varying Water Depths

Abstract

Rice (Oryza sativa L.) is the way of life for thousands of farmers across the coastal plain of Guyana and has recently advanced toward the highland Regions. However, there are many challenges facing the rice industry: such as flood water and water management which causes crop losses during the early growth stage, cost of mechanical irrigation during and after the reproductive stage, and flash flood during harvesting. In Guyana, pre-germinated seeds are sown in puddle fields that are drained within three to five days. Heavy rains coupled with a challenged drainage system and sometimes the additional cost of mechanical irrigation forces farmers to delay drainage after sowing. Further, the common practice of maintaining 7.6 to 15.2 cm of water after sowing to suppress red rice populations also adds to the cultivation challenges. This study aims to investigate the emergence of five rice genotypes (FG12-259, G18-110, G18-124, G17-109 and Aromatic gold), and two cultivated varieties (GRDB FL 10 and GRDB FL 15) under three different depths of standing water (7.6 cm, 15.2 cm and 22.8 cm), under control environment (bucket trial). The experiment was conducted during the second cropping season of 2020 using pre-germinated seeds in a three factorial completely randomized design. Differences in the rate of emergence among genotypes were observed when subjected to varying depths of water.  Excellent (over 80 %) emergence was observed at 7.3 cm water for all genotypes at between 7 to 13 DAS. It was established that all rice genotypes studied can provide good seedling establishments in fields under 15.2 cm of water. Strain FG12-259 shows the best emerged under 22.8 cm depths of water with 76.3% establishment followed by GRDB 15 (68.7%), GRDB 10 (62.7%) and G 18-124 (61.3%). These genotypes could provide good crop establishment in flooded conditions of up to 22.8 cm (9 inch) under Guyana ecosystem.