The effects of
nitrogen management on yield, quality,
nitrogen and dry matter accumulation and transportation of watermelon in
sand field were studied based on a field experiment. The results showed that too low or too high basal
nitrogen fertilzation was unfavorable to seedling growth of watermelon in
sand field, and no
nitrogen application at vine extension or fruiting stages limited the formation of 'source' or 'sink'. At the same
nitrogen rate, compared with the traditional T1 treatment (30% basal N
fertilizer + 70% N
fertilizer in vine extension), the
nitrogen and dry matter accumulation of vegetative organs of T4 treatment (30% basal N
fertilizer + 30% N
fertilizer in vine extension + 40% N
fertilizer in fruiting) and T6 treatment (100% basal N
fertilizer + NAM) were reduced significantly, but the
nitrogen and dry matter accumulation of fruit were increased significantly in the
flushing period. The
nitrogen transportation ratio and
nitrogen contribution ratio of T4 were 33.6% and 12.0%, respectively. Compared to T1, the
nitrogen harvest index,
nitrogen fertilizer partial factor productivity and
nitrogen fertilizer recovery efficiency of T4 and T6 treatments increased by 14.1% and 12.7%, 11.6% and 12.5%, 5.3% and 8.7%, respectively, and yield of watermelon increased by 11.6% and 12.5%, the soluble
sugar, effective
acid, the ratio of
sugar and
acid, Vc content increased by 16.5% and 11.7%, 4.5% and 2.8%, 19.4% and 13.4%, 35.6% and 19.0%, respectively. Therefore, T4 and T6 treatments were the optimal
nitrogen fertilizer management mode which could not only achieve high yield and quality but also obtain high
nitrogen fertilizer use efficiency in
sand field. T6 treatment was the best
nitrogen fertilizer management mode considering reduction of fertilizing labor intensity and extending service time of gravel-mulched field.