African Journal of
Agricultural Research

  • Abbreviation: Afr. J. Agric. Res.
  • Language: English
  • ISSN: 1991-637X
  • DOI: 10.5897/AJAR
  • Start Year: 2006
  • Published Articles: 6691

Full Length Research Paper

Genotypic variation in coleoptile or mesocotyl lengths of upland rice (Oryza sativa L.) and seedling emergence in deep sowing

Simon ALIBU1,2, Yuri SAITO1, Hironobu SHIWACHI1 and Kenji IRIE1*
  1Department of International Agricultural Development, Graduate School of Agriculture, Tokyo University of Agriculture 1-1-1, Sakuragaoka, Setagaya-ku, Tokyo 156-8502, Japan. 2National Crops Resources Research Institute (NaCRRI). P. O. Box 7084 Kampala, Uganda.
Email: [email protected]

  •  Accepted: 08 October 2012
  •  Published: 31 December 2012

Abstract

 

Rain-fed upland rice (Oryza sativa L.) is one of the important crops in Sub-Saharan Africa (SSA) accounting for over 40% of the area under rice cultivation. In SSA, upland rice is primarily established by dry direct seeding (DS), which saves time and labour, although DS is associated with poor seedling emergence and establishment. It is thought that coleoptile and mesocotyl elongation in rice seedlings enhance emergence in deep sowing. A screen house study was conducted from May to December 2011 at Tokyo University of Agriculture in Japan to determine the effect of coleoptile and or mesocotyl elongation on seedling emergence in deep sowing. Six upland rice genotypes which vary in coleoptile + mesocotyl lengths, and another ten genotypes varying only in mesocotyl lengths were selected and evaluated for seedling emergence at 2, 4, 6 and 8 cm sowing depths. The experiment was laid out in a split-plot design based on randomised complete blocks. Seedling emergence was significantly reduced by sowing depth. Across the genotypes, seedling emergence was not associated with coleoptile + mesocotyl length. And although coleoptile and mesocotyl lengths both increased with sowing depth, seedling emergence in deep sowing was affected largely by mesocotyl elongation rather than coleoptile elongation. We found that only those genotypes that significantly elongated their mesocotyls like Nutsurikui and Plu-go were able to emerge from deep sowing. Our results therefore suggest that seedling emergence in dry direct seeded upland rice can be improved by planting genotypes with long mesocotyls.

 

Key words: Coleoptile, dry direct seeding, mesocotyl, upland rice.