Grouping of spring wheat recombinant inbred lines in term of phenological and partitioning of assimilates in normal and water deficit conditions

Introduction Grain growth in wheat depends on current photosynthesis and stem water-soluble carbohydrates (WSC). In semiarid regions with terminal drought, grain filling in wheat crops may depend more on stem WSC content than on current assimilates. Reduction in grain yield under drought is attributed to shorter duration of linear grain growth despite increased contribution of stem reserves to grain yield. The amount of stem reserves is measured either by changes in stem dry weight (indirect method) or by stem WSC content (direct method). Genotypic variation in the rate and duration of linear grain growth and in percent contribution of stem reserves to grain yield has a little evaluated in wheat. Materials and methods The objectives of this study were grouping of spring wheat recombinant inbred lines in term of phenological and partitioning of assimilates in normal and water deficit conditions. Plant materials used in this experiment, include 148 bread wheat recombinant inbred lines derived from the cross between Yecora Rojo and genotype No. 49. Lines were produced at Riverside University and through of Center of Excellence Molecular Breeding, University of Tabriz was placed at the disposal of this research. Studied lines with parents were planted on research farms of Mahabad University and Miyandoab Agricultural Research Center in 2014-2015. In both experiments used alpha lattice design with two replications under normal and water defect conditions. Irrigation in stress and non-stress treatments was done after 90 mm evaporation from class a pan, depending on the temperature and evapotranspiration until heading stage. In water deficit stress treatment, irrigation was stopped at heading stage. Measuring of these traits were done sampling before and anthesis stage. Results and discussion According to the combined analysis there was a significant difference between two normal and water deficit conditions in terms of days to head, remobilization, grain yield and remobilization portion in grain yield. Also genotypes had significant difference for all traits. Also, grain yield had a positive and significant correlation with days to heading, stem partitioning, spike partitioning and the remobilization rate in both conditions. Based on the results of cluster analysis, genotypes were classified into 4 groups in both conditions. In both conditions, genotypes 7, 17, 27, 32, 40, 50, 58, 62, 67, 69, 83, 106, 107 and 138 were classified in cluster number four which had the highest values of phonological traits, photosynthetic allocation and grain yield. These genotypes were identified as suitable genotypes for breeding programs to create high yielding cultivars. In factor analysis based on principle component analysis, in both conditions three factors were recognized that explained 77.85 and 68.76 percent of total variation of data under normal conditions and water deficit conditions respectively. Conclusions In this study, grain yield had a positive and significant correlation with days to heading, stem partitioning, spike partitioning and the remobilization rate in both conditions therefore genotypes with high values of these traits, had a high grain yield potential. Genotypes of 7, 17, 27, 32, 40, 50, 58, 62, 67, 69, 83, 106, 107 and 138 were identified as suitable genotypes for breeding programs to create high yielding cultivars.