Effect of water control and plastic-film mulch on growth and the range of size inequalities in spring wheat (triticum aestivum) populations

Abstract

This study was conducted to determine the effect of water supply regimes and plastic-film mulching on the harvest index (HI), reproductive allocation (RA), and the range of size inequalities in spring wheat (Triticum aestivum) populations, and to explore the mechanisms causing them. Grain yield, biological yield, HI, and RA of spring wheat decreased significantly (P < 0.001) along the irrigation gradient (applied water decreased from 0.35 to 0.175 to 0 m3 m−2). Either mulched or non-mulched, the range of size inequalities always increased. HI and RA in the mulched treatment were significantly lower than in the non-mulched treatment (P < 0.05). Results suggest that the range of size inequalities in spring wheat populations are closely correlated with the water regime in the field, and that under greater drought stress there are relatively smaller plants with lower HI. A greater range of size inequalities may result in growth redundancy. Appreciable growth redundancy occurred in spring wheat populations mulched with plastic film, which may result from the exacerbated interplant competition and self-thinning. Thus, spring wheat cultivation with plastic-film mulching was not the best method, although grain yields increased 38.5% in mulched treatments compared with non-mulched control plots. © 2005 Taylor & Francis Group, LLC.