Spike Differentiation in Winter Wheat (Triticum aestivum L.) Mulched with Plastic Films During Over-Wintering Period

Abstract

To determine the effects of plastic film mulching on spike differentiation in winter wheat, two varieties (3291 and XZ25) and seven mulching treatments consisting of three mulching dates and two film removal dates and a non-mulched control (CK) were used. In the film-mulched treatments, the increase in weekly minimum soil surface temperature due to mulching was 4.1°C (P < 0.01) during the entire mulching period, while the weekly maximum temperature increased by 6.6°C (P < 0.05) only during the first and the last several weeks of observation. Spike differentiation was hastened by 19 to 35 days and the duration prolonged by 14 to 32 days in different film-mulched treatments. Early mulching extended the spike differentiation process, while delayed removal had little effect. Compared with variety XZ25, which was bred in a relatively low latitude, spike differentiation in variety 3291 was more sensitive to film mulching. The spikelet and floret numbers per main stem spike were significantly increased in all treatments with film mulching, while the grain number per spike was only increased in earliest mulching treatments. Linear correlations were found between spikelet number and the duration from apex elongation stage to apical spikelet formation, and between floret number and the period from floret initiation to tetra-sporophyte stage. No significant relationship was observed between grain number and the duration of spike differentiation. Findings from this study have been used to refine recommendations for wheat growers in northwestern China as to the best timing and duration of mulching for optimum grain yield.