In this study, the effects of the plant growth regulator trinexapac-ethyl (TE) combined with different sowing densities on fieldgrown rice (Oryza sativa L.) plant length, lodging, and grain yield were evaluated over 2 growing seasons. | Turkish Journal of Agriculture and Forestry Turk J Agric For (2013) 37: 257-264 © TÜBİTAK doi: Research Article Control of lodging and reduction in plant length in rice (Oryza sativa L.) with the treatment of trinexapac-ethyl and sowing density 1, 2 3 4 Rasim ÜNAN *, İsmail SEZER , Mevlüt ŞAHİN , Luis A. J. MUR 1 Trakya Agricultural Research Institute, Edirne, Turkey 2 Faculty of Agriculture, Ondokuz Mayıs University, Kurupelit, Samsun, Turkey 3 The Central Research Institute for Field Crops, Yenimahalle, Ankara, Turkey 4 Institute of Biological, Environmental, and Rural Sciences, Aberystwyth University, Ceredigion, United Kingdom Received: Accepted: Published Online: Printed: Abstract: In this study, the effects of the plant growth regulator trinexapac-ethyl (TE) combined with different sowing densities on fieldgrown rice (Oryza sativa L.) plant length, lodging, and grain yield were evaluated over 2 growing seasons. Two different rice cultivars (Karadeniz and Osmancik-97), 3 different sowing densities (400, 500, and 600 seeds m–2), and 4 different doses of TE (0, 100, 200, and 300 g ai ha–1) were compared. The experiments were designed in a randomized block design in factorial ordering with 3 replicates. An increase in sowing density led to an increase of lodging, but it did not have a significant impact on plant length and grain yield. There was a significant correlation between lodging and plant length. A sowing density of 500 seeds m–2 is the optimum value among all sowing densities, and the highest yield was obtained from Osmancik-97 among all the cultivars. Irrespective of genotype and sowing density, treatments with 100 and 200, but not 300, g TE ai ha–1 increased rice yield. All doses of TE reduced lodging and plant length. By regression analyses, the optimal TE dose was predicted to be 170 g ha–1. Key words: Lodging, plant length, rice .
