Natural variation at the DEP1 locus enhances grain yield in rice
Grain yield is controlled by quantitative trait loci (QTLs) derived from natural variations in many crop plants. Here we report the molecular characterization of a major rice grain yield QTL that acts through the determination of panicle architecture. The dominant allele at the DEP1 locus is a gain-of-function mutation causing truncation of a phosphatidylethanolamine-binding protein-like domain protein. The effect of this allele is to enhance meristematic activity, resulting in a reduced length of the inflorescence internode, an increased number of grains per panicle and a consequent increase in grain yield. This allele is common to many Chinese high-yielding rice varieties and likely represents a relatively recent introduction into the cultivated rice gene pool. We also show that a functionally equivalent allele is present in the temperate cereals and seems to have arisen before the divergence of the wheat and barley lineages. 
Erect leaves caused by brassinosteroid deficiency increase biomass production and grain yield in rice
New cultivars with very erect leaves, which increase light capture for photosynthesis and nitrogen storage for grain filling, may have increased grain yields1. Here we show that the erect leaf phenotype of a rice brassinosteroid–deficient mutant, osdwarf4-1, is associated with enhanced grain yields under conditions of dense planting, even without extra fertilizer. Molecular and biochemical studies reveal that two different cytochrome P450s, CYP90B2/OsDWARF4 and CYP724B1/D11, function redundantly in C-22 hydroxylation, the rate-limiting step of brassinosteroid biosynthesis. Therefore, despite the central role of brassinosteroids in plant growth and development, mutation of OsDWARF4 alone causes only limited defects in brassinosteroid biosynthesis and plant morphology. These results suggest that regulated genetic modulation of brassinosteroid biosynthesis can improve crops without the negative environmental effects of fertilizers. 
Natural variation in GS5 plays an important role in regulating grain size and yield in rice
Increasing crop yield is one of the most important goals of plant science research. Grain size is a major determinant of grain yield in cereals and is a target trait for both domestication and artificial breeding1. We showed that the quantitative trait locus (QTL) GS5 in rice controls grain size by regulating grain width, filling and weight. GS5 encodes a putative serine carboxypeptidase and functions as a positive regulator of grain size, such that higher expression of GS5 is correlated with larger grain size. Sequencing of the promoter region in 51 rice accessions from a wide geographic range identified three haplotypes that seem to be associated with grain width. The results suggest that natural variation in GS5 contributes to grain size diversity in rice and may be useful in improving yield in rice and, potentially, other crops2. 
Assessing the Effects of Water Management Regimes and Rice Residue on Growth and Yield of Rice in Uganda
Aim: This study was conducted to assess the influence of different water and rice straw management practices and rice genotypes on growth and yield of rice in Uganda.
Study Design: Field experimental design was a Randomized Complete Block Design while the screen house study design was a Completely Randomized Design.
Place and Duration of Study: The study was conducted in the field at National Crops Resources Research Institute (NaCRRI) Namulonge and in the screen house at Kyambogo University during the period of February-July 2013.
Materials and Methods: Ten rice genotypes obtained from the cereals program at NaCRRI Namulonge were grown under different water management regimes, with and without rice straw incorporation both in the field and screen house. Water management regimes used were alternate wetting and drying (AWD), continuous flooding (CF) and continuous drying (CD).
Results: A significant variation in grain yield was observed among rice genotypes and under different water management regimes (P<0.001). Use of rice straw influenced rice yield in the screen house (P<0.001) but not in the field (P=0.23); interactions of water management x genotype and water management x rice straw x genotype influenced rice yield in the field (P=0.003) but not in the screen house (P=0.5). Higher yield gain was observed under the water-saving technology alternate wetting and drying compared to continuous flooding or drying.
Conclusion: This study has indicated significant variations in field performance of rice under different water management regimes and rice straw usage. These findings are therefore important because they suggest that efficient management of water resources and rice residues from rice fields coupled with the use of drought tolerant rice varieties could be an effective integrated approach to improve rice yield and an adaptation strategy to the observed climate variability. 
Relationship of Yield and Yield Related Traits of Some Traditional Rice Cultivars in Sri Lanka as Described by Correlation Analysis
Aims: To understand the relationship between individual trait and yield of one hundred rice cultivars according to Pearson’s correlation coefficient.
Study Design: Completely randomized block design with four replicates. Twenty plants were evaluated in each replicate and eighty plants were evaluated in each cultivar in four replicates.
Place and Duration of Study: Faculty of Agriculture, University of Ruhuna, Sri Lanka in 2011-2013.
Methodology: Data were collected in 80 plants of four replicates on: plant height (cm), number of tillers per plant, number of fertile tillers per plant panicle length (cm), panicle weight (g), number of spikelets per panicle, number of fertile spikelets per panicle, 100 grain weight (g), days to maturity and yield per plant (g). Pearson’s correlation coefficients were calculated using SPSS.
Results: According to statistical analysis grain yield was significantly and highly correlated with number of fertile spikelets/panicle (r = 0.765), panicle weight (r = 0.727), number of spikelets/panicle (r = 0.638), filled grain percentage (r = 0.620), number of fertile tillers/plant (r = 0.611), number of tillers/plant (r = 0.575). Hundred grain weight (r = 0.336) and plant height (r = 0.278) were also correlated with at 1% significant level. None of the studied trait was negatively correlated with the yield.
Conclusion: Fertile spikelets per panicle, panicle weight, number of spikelet per panicle and filled grain percentage can be considered as good criteria for selection of rice cultivars suitable for breeding programs. 
 Huang, X., Qian, Q., Liu, Z., Sun, H., He, S., Luo, D., Xia, G., Chu, C., Li, J. and Fu, X., 2009. Natural variation at the DEP1 locus enhances grain yield in rice. Nature genetics, 41(4), pp.494-497.
 Sakamoto, T., Morinaka, Y., Ohnishi, T., Sunohara, H., Fujioka, S., Ueguchi-Tanaka, M., Mizutani, M., Sakata, K., Takatsuto, S., Yoshida, S. and Tanaka, H., 2006. Erect leaves caused by brassinosteroid deficiency increase biomass production and grain yield in rice. Nature biotechnology, 24(1), pp.105-109.
 Li, Y., Fan, C., Xing, Y., Jiang, Y., Luo, L., Sun, L., Shao, D., Xu, C., Li, X., Xiao, J. and He, Y., 2011. Natural variation in GS5 plays an important role in regulating grain size and yield in rice. Nature genetics, 43(12), pp.1266-1269.
 Awio, T., Bua, B. and Karungi, J. (2015) “Assessing the Effects of Water Management Regimes and Rice Residue on Growth and Yield of Rice in Uganda”, Journal of Experimental Agriculture International, 7(2), pp. 141-149. doi: 10.9734/AJEA/2015/15631.
 Ranawake, A. L. and Amarasinghe, U. G. S. (2014) “Relationship of Yield and Yield Related Traits of Some Traditional Rice Cultivars in Sri Lanka as Described by Correlation Analysis”, Journal of Scientific Research and Reports, 3(18), pp. 2395-2403. doi: 10.9734/JSRR/2014/12050.