Abstract The rapid increase of pasture containing lucerne (Medicago sativa) has increased demands for the continual supply of high quality seed, especially in China. Irrigation times are important for seed production. Five irrigation treatments, including (1) irrigation at podding and flowering and regrowth (when the shoots start emerging from the crown); (2) irrigation at podding and regrowth stages; (3) irrigation at flowering and regrowth; (4) irrigation at branching and regrowth; (5) irrigation at the regrowth stage only, were used to determine the effect of irrigation times on seed yield, its components, and seed distribution within plant in this field experiment. Treatment 5 is the local farmer irrigation practice, and was used as the control treatment. There were significant differences in seed yields between treatments, but not between two successive seasons. Irrigation at regrowth and podding produced the greatest seed yield, followed by, in decreasing order: regrowth stage; flowering and regrowth stage; podding and flowering and regrowth stage; branching and regrowth stage. Compared with irrigation at the regrowth stage only, irrigation at podding and regrowth stages significantly increased the fertile shoots per plant, racemes per plant and pods per raceme, which contributed to higher seed yield. Irrigation at flowering or branching greatly increased the shoots per plant, but reduced the fertile shoots per plant, and further decreased the seed yield. Seed weight per 100 pods in the treatment irrigated in the podding and regrowth stages was significantly greater than that in the other irrigation treatments. This study also showed that irrigation influenced the seed distribution in the plant, with more frequent irrigations producing seeds on the tops of plants.
Keywords irrigation time; lucerne; seed yield components; spatial distribution
A06033; Online publication date 2 July 2007; Received 14 May 2006; accepted 24 March 2007
New Zealand Journal of Agricultural Research, 2007, Vol. 50:
285–290
0028–8233/07/5003–0285 © The Royal Society of New Zealand 2007
PDF file of entire paper: Print-quality (767K) | screen-quality (446K)