EFFECT OF SEEDING DATE ON YIELDS AND QUALITY OF GREEN FORAGE CROPS

Abstract

Forage kale (Brassica oleracea L.), rape (B. napus L.), radish (Raphanus sativus L.), and Chinese cabbage (B. campestris sensulato L.) × stubble turnip (B. rapa L.) hybrid were seeded at monthly intervals between late-May and late-August over 3 yr. Kale was harvested in early November while rape, radish, and turnip hybrid were targeted for harvest 60–70 d after seeding. The dry matter yield of kale declined as the seeding dates were delayed. The primary growth of rape, radish and turnip hybrid was the same for May, June and July seedings, but seeding in August lowered the yields by 25–38%. The in vitro dry matter disappearance was high, ranging from 850 to 920 g kg−1. The total N concentration of whole plant tissue, leaves, stem + petioles, and roots and S-methylcysteine sulphoxide (SMCO) concentration of whole plants increased as the seeding date was delayed. We concluded that kale should be planted by mid-June for high yields. Fodder rape, radish, and turnip hybrid had similar yields with seeding from spring until mid-July. In vitro dry matter disappearance and N concentrations were high for all species.Key words: Brassica oleracea, B. napus, B. rapa, Raphanus sativus, chemical composition, digestibility