Our findings of reduced yields with limiting N and S supply are in line with the body of evidence from other studies. Hence, at harvest time, the head weight differed as a conse- quence of the amount of N and S supplied. Plants receiving an optimal amount of N had a higher average head weight (213.89 ± 22.75 g) as compared to those supplied with an insufficient amount of N (72.60 ± 8.33 g) (Fig. 1).
Figure 1: Influence of N and S supply on head mass (g FM plant–1) of broccoli “Monaco”. Values represent the mean of three experiments and three replications. Means with the same letters are not significantly different ( p < 0.05).
Moreover, the S supply also influenced the head weight. When S was insufficient (0.2 g) and N was optimal (4.0 g), head weight was reduced by up to 18%. Our investigations showed that an insufficient S supply limited the utilization of N already present in the plant. Nitrogen and sulfur are both involved in protein biosynthesis; thus, a shortage in the S supply also limits the utilization of applied N (Cecotti, 1996).