Spike removal effects on dry matter production, assimilate distribution and grain yields of three soft red winter wheat genotypes

Abstract

The effects of spike removal on dry matter partitioning were studied in three soft red winter wheat ( Triticum aestivum L.) genotypes. Field plots were planted in a randomized complete block design with a split plot arrangement of treatments (genotypes as whole plots and spike treatments as subplots). Spike treatments were with either intact spikes (control) or with 25% spike removal (SR) at 4 days post-anthesis. Dry weight and total nonstructural carbohydrate (TNC) content of tiller organs (spike, peduncle, stem and leaf) were determined at 7-day intervals from the data of SR treatment until physiological maturity. Grain yields were decreased 25% in the SR compared to the control treatment, whereas kernel test weight was not significantly different between treatments. Both dry weight and TNC content of leaf, peduncle, and stem samples were greater in the SR than in the control subplots 1 or 2 weeks after the SR treatment. Averaged across genotypes, there was a net dry weight increase of 1.05 g in control samples throughout the grain-filling period. By comparison, spikeless tillers in the SR subplots lost 1.89 g of dry matter between anthesis and maturity. These findings suggested that dry matter produced by a spikeless tiller was not translocated to intact tillers of the same plant in sufficient quantities to impact yield.