Effect of planting density on growth characteristics and grain yield increase in successive cultivations of two rice cultivars

Abstract

Abstract Rice (Oryza sativa L.) recultivation plays an important role in increasing land productivity and efficiency in crop rotation. Planting density (PD) is an important agronomic factor to achieving maximum grain yield (GY). The current study aimed to determine the best PD for the first cultivation and recultivation of rice. The experiment was conducted as a split plot based on the randomized complete block design with three replications at Ghaemshahr University, Mazandaran (northern Iran) from 2013 to 2014. Treatments consisted of cultivars ‘Tarom Hashemi’ and ‘Koohsar’ at two levels as the main factor and PDs at the three levels of 16, 25, and 33.3 hills m–2 with planting spaces of 25 × 25, 20 × 20, and 30 × 10 cm2, respectively, as the subfactor. The results of the current study showed that cultivar for the first cultivation and year for the recultivation had a significant effect on GY. Planting density had a significant effect on GY in both first cultivation and recultivation. The GY of Hashemi in the first cultivation (36.1%) and recultivation (18.5%) was higher than that of Koohsar. Grain yield in the first cultivation and recultivation had an increasing trend; PD increased up to 33.3 hills m–2 as 19.9 and 21.4% in the first cultivation and recultivation, respectively, due to the increase in number of panicles m–2 (30.1 and 30.6%, respectively). Hashemi is suitable for the first cultivation. It is noteworthy, also, that a density of 33.3 hills m–2 is recommended for the first cultivation and recultivation.