Does Use of Unbordered Plots Affect Estimation of Upland Rice Yield?

Abstract

Advance in crop genomics have led to a demand for more accurate and precise phenotyping of a large number of genotypes for discovering genes and mechanisms underpinning important agronomic traits. The use of unbordered plots for field phenotyping is one approach for reducing the resources needed, but competition effects between neighboring lines may confound varietal performance. Four field experiments were conducted in Benin to examine whether grain yields of 14 diverse upland rice (Oryza sativa spp.) varieties determined in unbordered one‐row or two‐row plots differ from those measured in self‐bordered four‐row plots and to examine if statistical models including covariates based on plant characteristics (height, panicle number, and days to heading) for correcting competition effect can improve the estimation of the yield in unbordered plots. Mean grain yield across all varieties ranged from 118 to 378 g m−2 in four experiments. There was no significant variety × row number interaction effect on grain yield, except for the highest yielding experiment. In that experiment, the variety × row number interaction was significant for one‐row versus four‐row plots, but not for two‐row versus four‐row plots. In one‐row plots in this high‐yielding experiment, the neighborhood covariate model based on panicle number improved residual mean square by 20%, but relative selection intensity by 3% only. Similarly, the covariate models based on height or panicle number in both one‐ and two‐row plots in the other experiments improved just 4%. We conclude that unbordered one‐ or two‐row plots can provide reasonable estimates of grain yield of upland rice without any bias due to competition effects, except for high‐yielding one‐row plots (>350 g m−2).

Plant Characteristics of High‐Yielding Upland Rice Cultivars in West Africa

“…‡ NA, data not available (not recorded). § Data on yield were reported by Saito et al (2015). ¶ All the data were reported by Saito et al (2012).…”

“…Soil texture is loamy sand in AfricaRice farm and Bassila, sandy loam in Glazoue, and clay loam in Cobli, and rainfall patterns were reported by Saito et al (2014). All the data on yield were already reported in previous publications except for the third set (Saito et al, 2012, 2014, 2015). The following data shown in this study were not reported in the previous studies: yield components of IR 74371‐3‐1‐1 and NERICA 1 in the first set, plant characteristics of all the cultivars that were periodically evaluated in the second and third sets, and nutrient uptake and use efficiency of all the cultivars in the fourth set.…”

“…In the next section, I describe the cultivars present in this study followed by description of the third and fourth sets of trials. Material and methods for the first and second sets of trials are reported by Saito et al (2014) and Saito et al (2015), respectively, and are not described.…”

“…Such information would provide great benefits for upland‐rice breeding programs seeking to identify or develop promising cultivars efficiently. Thus, in this paper, I compiled the results on yield and plant characteristics from previous studies (Saito et al, 2012, 2014, 2015) and newly conducted experiments. The objectives of this study were to (i) quantify the yield advantages of Aus 257 and IR 74371‐3‐1‐1 over upland NERICA 1, (ii) characterize their plant characteristics, and (iii) summarize important plant characteristics of high‐yield upland rice cultivars through compiling information from previous studies as well as this study to provide the future implications for breeding program.…”