MOHAMMADI, Mohtasham Dryland Agricultural Research Institute - Gachsaran Station, ايران , KARIMIZADEH, Rahmatollah Dryland Agricultural Research Institute - Gachsaran Station, ايران , SHFEZADEH, Mohammad Kazem islamic azad university - Department of Agronomy, ايران

Source–Sink Limitation on Spring Bread Wheat Genotypes in High and Low-Production Environments

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Grain yield depends on the number of grains per unit area (sink) and the availability of assimilates (source) to fill these grains. The aim of the current work was to determine whether wheat yield in warm environments is limited in current cultivars by the size of the sink or by assimilates available for grain filling (source) using manipulation. Sink size was reduced at anthesis by removing all the spikelet along one side of the spike and source size was reduced at anthesis by removing all leaf blades from a main stem. This research was conducted with six bread wheat cultivars using randomized complete block design with three replications in two separate experiments in 2011-12 under dryland and full irrigated conditions. After 50% spikelet removal, individual kernel weight was from 42.9 to 53.5 mg with mean change: 9.1% and from 37.9 to 41.8 mg with mean change:10.9% in high input (full irrigation) and low input (dryland) conditions respectively. Defoliation decreased individual kernel weight of all cultivar and a new recently released cultivar for semi-tropical dryland regions of Iran (Karim) showed the lowest reduction. The source–sink modification in two independent experiments suggested that the yield of the current wheat cultivars is more sink- than source-limited and that breeding wheat with a larger sink size than in the current cultivars may lift the yield potential in favourable condition or increase the yield of wheat under heat and drought constraints.

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Assimilate , Bread wheat , Drought , Heat , Tolerance , Yield potential

Yuzuncu Yil University Journal Of Agricultural Sciences

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