Dynamics of root growth in spring wheat mulched with plastic film

Quantifying root growth can improve our understanding of the development of rhizoplane and rhizosphere structure of a crop and its relation to seed yield. A study was conducted in a semiarid environment in northwestern China to determine the seasonal and spatial patterns of root growth in spring wheat (Triticum aestivum L.) grown with and without plastic mulches. The seed of 'Lun-chun 20' was grown in polyvinyl chloride tubes filled with Yellow Mein sandy loam soil (Aridic Haplustoll). Mulched wheat had a greater (22%) root dry weight (DW) than unmulched wheat at Zadoks Growth Stage (GS) 22. Root DW increased rapidly from GS22 to GS73, with the rate of increase in root DW peaked at GS61. At a given GS during this period, the mulched wheat produced a significantly greater root DW than the unmatched wheat. For both mulched and unmulched wheat, the rate of increase in root DW declined after GS61 where roots penetrated down into the 100-cm soil layer. The greatest percentage of root DW was in the 10- to 20-cm soil depth, followed by the root DW in the 40- to 50-cm soil depth. At any given soil depth between 10 and 60 cm, the mulched wheat had a greater root DW than the unmulched plants. Root DW below 60-cm soil depth accounted for a small portion of the total weight and did not differ between the two mulch treatments. On average, the mulched wheat had 23% greater number of seeds per plant, 5% higher seed weight, and 28% higher grain yield than unmatched wheat. In semiarid northwestern China, the use of plastic mulches promoted spring wheat root development, root biomass production, and seed yield.