Postanthesis dry matter accumulation and redistribution in spring wheat mulched with plastic film

Spring wheat (Triticum aestivum L.) grown in semiarid climates shows a remarkable increase in grain yield when mulched with plastic film. Information on dry matter (DM) accumulation and redistribution in mulched plants is needed to understand the mechanisms of the yield improvement. A 2-yr field study was conducted to determine DM of various vegetative (leaves, stems) and nongrain (rachises, glumes, lemma and palea, and sterile florets) organs and final grain yield for spring wheat grown on a Yellow Mein sandy loam (Aridic Haplustoll) with and without plastic mulches. Dry matter of vegetative and nongrain organs in both treatments reached a maximum 3 wk after anthesis and then decreased rapidly. Grain DM increased from 190 mg plant(-1) at anthesis to an average of 2115 mg plant(-1) in mulched wheat and 1726 mg plant(-1) in unmulched wheat, by the fifth week after anthesis. The second internode from the spike contributed the greatest proportion (22-25%) to the total DM lost from the vegetative and nongrain organs, followed by the nag leaf (21-23%), the peduncle (11-15%), and the leaves below the nag leaf (8-10%). Basal leaves and stem segments, and nongrain organs contributed only 5 to 7% of the total DM mobilized. Compared with ummulched plants, the mulched plants accumulated greater (26%) DM at anthesis, mobilized a larger percentage of DM to grains after anthesis, and produced 36% more grain yield. Application of plastic mulches to spring wheat effectively increased dry matter production and mobilization from vegetative organs to grains.