Selection of hybrid rice to drought for development in rainfed lowland

Abstract

The objective of the research was to determine method and character for early selection of rice to drought and to obtain drought tolerant hybrid rice genotypes to be used further in rainfed lowland. Experiments were conducted from April 2011 until July 2012 at Seed Science and Technology Laboratory, IPB and BB Biogen greenhouse Cimanggu, Bogor, at Babakan Experiment Station, IPB, Bogor, and at irrigated lowland, Cikembar, Sukabumi, and rainfed lowland, Gantar, Indramayu. The study consisted of seven experiments. The results showed that: (1) Polyethylene glycol (PEG) 6000 could detect and differentiate the response of hybrid rice genotypes to drought stress in both germination and seedling stage. The use of 25% PEG 6000 in the seedling stage could detect early hybrid rice genotypes tolerant to drought and have a compatibility with grouping of genotypes tolerant to drought based on yield criteria in the field. Variables of root dry weight, shoot dry weight and leaf dryness score were to detect hybrid rice genotypes tolerant to drought at seedling stage. (2) Genotypes BI485A/BP12, BI485A/BP15 and BI559A/BP15 under drought stress conditions decreased root length less (17.6 - 26.9 percent) than the IR64, the sensitive check variety (33.6 percent). Their grain weight, harvest index and grain yield (2.82, 2.58 and 2.72 ton ha-1) were higher than other genotypes. Moreover they were earlier to harvest, shorter in grain filling period and had sensitivity index to drought ≤ 0.50. Hybrid genotype tolerant to drought i.e BI599/BP15 under drought stress conditions had less stomatal density, maintained higher leaf relative water content, and contained non-structural carbohydrates in stem, sheath and leaf less than other genotypes. Genotypes BI485A/BP12, BI485A/BP15 and BI559A/BP15 were tolerant to drought and potentially could be developed for rainfed lowland; (3) The yield of these genotypes under irrigated lowland were not significantly different from those of Ciherang and Hipa 7 (i.e. 5.63, 6.87 and 6.30 ton grain ha-1, respectively). BI599A/BP15 genotypes under severe drought at rainfed lowland yielded 0.90 ton grain ha-1, whereas Hipa 7 and Limboto reached 0.34 and 0.29 ton grain ha-1, respectively.