Sowing date and water stress effects on sole and intercropped maize/pea cultivars under controlled conditions

Abstract

Controlled experiments were conducted in Glasshouse 7 at the Experimental Grounds, Plant Sciences Laboratories, Whiteknights, The University of Reading, in 2000 and 2001. Relative sowing date and water stress on maize and pea sole and intercrops were investigated under controlled conditions in 2 years. A two-factor in a completely randomized design was used in both years, comprising two varieties of maize and pea with contrasting morphologies and sowing pea simultaneously with maize or 14 days after maize as well as two levels of water stress. The two maize varieties were ‘Nancis’ with erectophile leaf habit, and ‘Sophy’ with a planophile leaf habit; the two pea varieties were ‘Maro’, a normal-leaved pea, and ‘Princess’, a semi-leafless pea. In the first-year study in 2000, intercropping maize with pea was generally more advantageous than when either crop was sown sole. Delaying the time of intercropping of pea by 14 days after sowing maize increased the kernel yield of maize compared to when intercropped simultaneously. The best intercropping combination in this study, using the Land Equivalent Ratio (LER) index, was when the normalleaved pea ‘Maro’ was intercropped with the erectophile leaf maize ‘Nancis’ 14 days later. In the second-year study in 2001, intercropping and water stress reduced intercropped maize yield, but the reduction was greater when maize was intercropped with the normal-leaved pea ‘Maro’ (212%) than the semi-leafless pea ‘Princess’ (127%). Water stress increased the erectophile-leaved maize ‘Nancis’ yield when intercropped with the normal-leaved pea ‘Maro’ (52%), due to an increase in partitioning of dry matter to generative organs compared to the vegetative organs. All intercropping combinations were advantageous, using the averages of the LER and Area-Time Equivalent Ratio (ATER) indices; but the benefits were slightly higher with the planophile-leaved maize ‘Sophy’ than the erectophile-leaved maize ‘Nancis’.