Effects of between-row and within-row spacing on alfalfa seed yields

Abstract

Proper between-row and within-row spacing is essential for optimizing alfalfa seed yields and stand longevity. Using three alfalfa (Medicago sativa L.) cultivars (WL232HQ, Derby, and Algonquin), we conducted a field study from 2004 to 2007 to evaluate the effects of three between-row spacing treatments (60, 80, and 100 cm) and four within-row spacing treatments (15, 30, 45, and 60 cm) on seed yield, seed yield components, plant height, basal stem diameter, and lodging. Our hypothesis was that the intermediate between-row and within-row spacing would gradually improve seed yields in later years. The highest seed yields were obtained with 60-cm between-row spacing and 15-cm within-row spacing in 2004, but with 80-cm between-row spacing and 30-cm within-row spacing in 2006 and 2007. The significant year x between-row spacing and year x within-row spacing interactions for seed yield indicated that 80-cm between-row spacing and 30-cm within-row spacing produced the best seed yields as years advanced, and our results confirmed this. With the increase of within-row spacing, stems per square meter decreased, while racemes per stem increased significantly. The effects of between-row and within-row spacing on seeds per pod, however, were not significant in four years. The results suggest that 80-cm between-row spacing and 30-cm within-row spacing can decrease the risk of lodging and optimize seed yields in the third and fourth harvest years. © Crop Science Society of America.