Effect of plant spacing and rice variety on vegetative growth and rice performance at acidic conditions of Iyanomo, South-South Nigeria

Abstract

Rice (Oryza sativa L.) is one of the major staple food crops for about 65% of the world’s population as the crop is valued for its food contents. The recognition of poor performance of local rice varieties suggests that priority should be given to improved rice varieties with good performance including adaptability potential. Although cultivation of rice is a common practice in Nigeria, little is known about the response of rice crop to different spacing in Iyanomo. In Iyanomo village, planting rice has been hampered by lack of improved varieties. A rice field experiment was conducted at RRIN Headquarters, Iyanomo during the main wet cropping season in 2017. The objective of the study was to evaluate the influence of plant spacing on early performance (vegetative growth) of two rice varieties (NERICA 2 and NERICA 7) in local environments of Iyanomo using NERICA 1 (a high-yielding, disease-resistant and early-maturing upland rice variety as standard). The factorial experiment was laid out in a randomized complete block design in a split-plot arrangement with five replications.  The three NERICA varieties were planted at three spacing (10 x 10 cm; 20 x 20 cm; and 30 x 30 cm). Organic manure (cow dung fertilizer) and inorganic fertilizer (Urea) were applied prior to planting at the rate of 3,000 kg ha ^-1 and 100 kg ha ^-1 at 2 weeks after planting respectively. Weeds were adequately controlled using hand hoe. At 6 weeks after planting, plants were measured and the data on plant height, leaf length and leaf width were recorded from six randomly sampled plants within the middle of each sub-plot measuring 1.7 x 2.4 m (4.08 m^-2) excluding border plants. The operation was repeated at weekly interval (for a period of six weeks and at the end of the experiment, the yields of the rice straw was determined, per hectare, from a plot measuring 1.7 x 2.4 m (4.08 m^-2) at 9 weeks after transplanting. The statistical software ‘R STUDIO’ was used to analyze the data (for plant height, leaf length and leaf width) and LSD at 5% probability level was used as the mean separation. Results indicate that in NERICA 1, the best spacing observed for the highest plant height and leaf length was 30 x 30 cm, while in NERICA 2, 20 x 20 cm had higher values for plant height, leaf length, and leaf width. For leaf width, the relatively high density at which the two rice varieties performed optimally was 20 x 20 cm suggesting that the spacing allowed maximum utilization of growth resources. The spacing of 10 x 10 cm had no effect on plant height, leaf length and leaf width for NERICA 1 and NERICA 2. The 30 x 30 cm spacing became more important in determining the leaf length and leaf width in NERICA 1 and NERICA 2. Similarly, 20 x 20 cm spacing had a larger and positive effect on the plant width of both varieties. The yields of rice straw indicated that the higher the plant populations, the higher the straw yields. NERICA 1 had the best straw yield. A spacing of 10 x 10 cm is recommended for straw production. The observed difference suggests that performance among the varieties was due to spacing. This paper provides an overview of progress in testing the vegetative growth of rice varieties. It is recommended that further work on the rice varieties be conducted on grain yields.