Responses of modern and local Thai rice varieties to the aerobic soil

Abstract

This study evaluated responses of modern and local Thai rices to find varieties that are suitable for growing in water-limited areas under aerobic and anaerobic soils. Nine rice varieties and two soil water conditions were arranged as a factorial design in a completely random design (CRD) with three replications. The agronomic traits that were measured consisted of 50% flowering date, plant height, yield components, harvest index (HI), and grain yield plant-1. Growing rice under aerobic soil significantly reduced plant height, yield components and grain yield, compared with anaerobic soil. However, the reduction differed depending on the variety. The modern rice varieties tend to be more adapted to the aerobic soils, compared to local. Modern rice varieties, RD29, RD49, and RD57, and a local rice variety, Chiang Phatthalung, tend to be better adapted under aerobic soil. These were clearly indicated by the smallest reduction in some agronomic traits under aerobic compared to anaerobic conditions. The plant height of RD57 was 107.93/ 104.53 cm in anaerobic and aerobic, respectively. The tiller number plant -1 in RD57 was 15.2/ 8.8; panicle number plant -1 in RD57 was 14.67/8.7 and in RD29 12.6/7.7; spikelet number plant -1 in RD57 was 188/203 and RD49 was 185/189; filled grain plant -1 in RD57 was 166.8/161; empty grain plant -1 in Chiang Phatthalung was 76.6/45.87; filled grain (%) in Chiang Phatthalung was 57.3/62.1. A highly significant correlation was found between grain yield and the number of panicle plants-1 (R=0.75; P<0.001) under non-flooded conditions, which indicated that grain yields under aerobic soil largely depended on panicle initiation. Therefore, the panicle initiation stage should first be concentrated under water shortage. Thailand comprises a wide diversity of rice. Therefore, more varieties of both modern and local Thai rice should be studied further