Effects of nitrogen and phosphorus nutrition on the growth of asparagus seedlings

Abstract

N was applied at 50, 100 or 150 mg l −1 in factorial combination with P at 7.5, 15 or 22.5 mg l −1 to asparagus seedlings. There were 6 successional harvests. N and P increased shoot dry weight by increasing mean dry weight and number of shoots. Increasing P had no effect on shoot growth at 50 mg l −1 N. N increased root dry weight (crown and roots) by increasing root number, whereas P decreased root dry weight due to a decrease in mean root dry weight. N increased total plant dry weight, but P had no effect. N and P increased the partitioning of dry weight to the shoots, while partitioning to the roots increased with time. Plant analysis revealed that 2.6–2.7% N and 0.29–0.36% P, on a dry-weight basis, were present in the shoots at the later harvests with the higher concentrations of N and P. 100–150 mg 1 −1 N in combination with 15 mg l −1 P produced a seedling suitable for transplanting into commercial fields at 6 weeks from emergence.