Tillage, Seeding, and Nitrogen Rate Effects on Rice Density, Yield, and Yield Components of Two Rice Cultivars

Abstract

Research was conducted for 2 yr on a Crowley silt loam soil (fi ne, smectitic, thermic Typic Albaqualfs) near Crowley, LA to evaluate the main eff ects of tillage, seeding and N rate and potential interactions on rice (Oryza sativa L.) density, yield, and yield components. Two tillage systems (conventional and fall-stale seedbed), four seeding rates (162, 323, 484, and 646 seed m -2 ) and four N rates (101, 134, 168, and 202 kg ha -1 ) were evaluated. 'Jupiter' and 'Cheniere' a medium and long grain cultivar, respectively, were evaluated in separate experiments. Conventional tillage reduced rice plant density as compared with fall-stale seedbed tillage due to crusting following fl ush irrigation during seedling emergence. A tillage by N rate interaction was not observed, suggesting optimal N rates are similar for rice grown using a conventional or fall-stale seedbed. Rough rice grain yield was optimized at 202 and 168 kg N ha -1 for Jupiter and Cheniere, respectively. Grain yields were optimized for Jupiter at 323 seed m -2 , while Cheniere required a seeding rate of more than 323 seed m -2 . Panicle density was found to be the single most infl uential yield component on rice yield and was able to explain 49 and 51% of the variation in yield for Jupiter and Cheniere, respectively. Filled grain panicle -1 was inversely related to panicle density highlighting the ability of rice to tiller as a yield compensatory measure when less than optimum rice densities exist. However, total yield compensation may not be feasible at low seeding rates.

Effects of plant density on the performance of selected African upland rice varieties

“…All the previous studies mentioned in the previous paragraph are unanimous in showing the positive relation between panicles/m 2 and plant density. The same response was found by Harrell and Blanche (2010) for direct seeded rice in the USA and by Nakano et al (2012) for a Japanese highyielding rice for feed use. Huang et al (2013) reported an exceptional case for Chinese hybrid varieties that while the effect of plant density on panicles/m 2 was positive and significant for crops planted early, no significant relation was found for crops planted late.…”

“…The effects of plant density could be different if plant density is measured in terms of row spacing or seeding rate. Although Lampayan et al (2010) and Chauhan and Posner (2011), both of which adopted row spacing, and Harrell and Blanche (2010), which used seeding rate, report plant-density responses the patterns of which are essentially the same as those reported by the studies, including ours, which adopted the hill density, further research is needed to confirm differences in the effects of plant density among the different measures of plant density.…”

“…Therefore, the direction as well as the degree of changes in yield due to changes in plant density was largely determined by the changes in the number of spikelets Table 2 per square meter. It is generally the case, upland and lowland rice alike, that at lower levels of plant density till 25 to 50 hills/ha, panicles/m 2 is the most important yield component that determines the positive effects of plant density on yield (Yoshida, 1981;Akita, 1982b;Yamaguchi, 1982;Harrell and Blanche, 2010;Clerget et al, 2016).…”

Nitrogen Strategy and Seeding Rate Affect Rice Lodging, Yield, and Economic Returns in the Midsouthern United States

“…However, more recent research indicates that rice uses N more effi ciently and produces greater grain yields when applied in a single prefl ood application (Bollich et al, 1994;Norman et al, 2000;Slaton et al, 2003;Bond et al, 2008). Applying high rates of N in a single application can cause unwanted agronomic eff ects such as greater plant height which can result in potential grain yield loss due to lodging (Gravois and Helms, 1996;Slaton et al, 2003;Bond et al, 2008;Harrell and Blanche, 2010).…”

“…Recommended seeding rates for Louisiana rice production vary by variety, but range from 215 to 323 seeds m -2 . Th is allows for a fi nal plant population density of 108 to 161 seedlings m -2 (Saichuck et al, 2008;Harrell and Blanche, 2010). Research with older inbred cultivars suggests low seeding rates do not negatively impact grain yield (Jones and Snyder, 1987;Gravois and Helms, 1992;Ottis and Talbert, 2005;Harrell and Blanche, 2010) largely due to greater levels of tillering at low seeding rates (Schnier et al, 1990;Counce et al, 1992).…”