INFLUENCES OF N AND S INTERACTION ON GROWTH AND PUNGENCY OF CHINESE BUNCHING ONION (ALLIUM FISTULOSUM L.)

Abstract

Allium species are grown worldwide because of their commercial, nutritional and health value. To seek a high yield and gain much income, farmers apply a large quantity of fertilizer, especially N, which may increase the yield at the cost of quality. A pot experiment was carried out to investigate the growth and pungency (replaced by the enzymatically formed pyruvic acid (EPY)) of Chinese bunching onion (Allium fistulosum L.) as affected by N and S interaction, three levels of N and S were designed as 2, 6, 12 mM and 0.1, 2, 4 mM respectively in solutions of deionized water. Plants were grown in a waterproof place for 15 weeks and then harvested. Results indicated that plant growth and shoot dry matter yield were significantly affected by added N but not by S. Shoot dry weight increased with increasing N supply. Compared to the high N level (12 mM), S nutrition did not increase the shoot EPY content at the other two N levels, but the soluble solids contents (SSC) were relatively higher. Meanwhile, N may promote EPY synthesis and increase total EPY content, especially at a large application quantity. In addition, total N contents of root and shoot were affected significantly by added N but not by S. Total shoot S content had a significant correlation with the EPY content. As a consequence of this study it could be concluded that N nutrition could promote the plant growth, while S nutrition could increase the pungency of Allium species, most important of all, S application could promote total EPY content at a higher N supply rate.