Yield, Yield Components and Economic Returns of Upland Rice as Influenced by Population Densities and Cultivars in Uyo, Nigeria

Background: One reason for the low yield of rice in Nigeria is the use of inappropriate plant density. It has been found that as seeding rate increased; panicles m-2 significantly increased suggesting that adjustments in plant densities could enhance upland rice yield which constitutes 32% of the Nigerian rice growing area. Therefore, this study was undertaken to assess the yield, yield components and economic returns of upland rice as influenced by population densities and cultivars in Uyo, Nigeria
Study Design: A 6 x 5 factorial experiments laid out in a randomized complete block design with three replications were conducted in 2009 and 2010 at the University of Uyo Teaching and Research Farm, Use Offot, Uyo, Nigeria.
Methodology: Treatment combinations were six population densities: 1,600,000 plants ha-1 (i.e. 25 cm x 10 cm spacing x 4 plants), 1,066,666 plants ha-1 (i.e. 25 cm x 15 cm spacing x 4 plants), 800,000 plants ha-1 (i.e. 25 cm x 20 cm spacing x 4 plants), 640,000 plants ha-1 (i.e. 25 cm x 25 cm spacing x 4 plants), 533,333 plants ha-1 (i.e. 25 cm x 30 cm spacing x 4 plants) and 2,054,435 plants ha-1 (i.e. 25 cm x drilling) and five upland rice cultivars: FARO 43 , FARO 46, FARO55, FARO 56 and a popular local check - Otokongtian.
Results: Results indicated that the number of effective panicles m-2 increased significantly (P<0.05) with increase in density but not beyond 1,600,000 plants ha-1. The 640,000 and 533,333 plants ha-1 significantly increased the number and percentage of filled spikelets panicle-1. Increase in plant density significantly decreased 1000 seed weight while grain yield increased significantly with increase in population density except that the 1,600,000 density yielded significantly higher than the 2,054,435 density. The local check, Otokongtian, produced the highest number of effective panicles, followed by FARO 43. The FARO 56 produced the highest number of spikelets. Percentage filled spikelets panicle-1 did not follow a definite trend but FAROs 56 and 43 had higher percentage of filled grains. In both years, FARO 46 had the highest significant 1,000 seed weight while FARO 43 produced the highest significant grain yield. All the cultivars produced higher grain yield at higher than at lower densities
Conclusion: Although variations were observed between years, 1,600,000 plant density had the highest net benefit (Naira (N) ha-1 N 1.00 = 162 US Dollars) in both years (N383,074 and N303,554 for 2009 and 2010, respectively), which represented 789.65 – 806.24% returns on investment over the 640,000 density, followed by 2,054,435 density. Therefore, FARO 43 and 56 have great potentials for this agro-ecology particularly at 1,600,000 plants ha-1 density.