Abstract:

In the present study, broccoli cv. Bilyu was selected as experimental material, and a two-factor interactive experimental design was adopted. Three irrigation amounts, namely, W1 (80% of the maximum field capacity), W2 (60% of the maximum field capacity), W3 (40% of the maximum field capacity) and 3 nitrogen forms, namely, N1 (pure$NO^{-}_{3}-N$), N2 (proportion of $NO^{-}_{3}-N$ to $NH^{+}_{4}-N$ was 7∶3), N3 (proportion of $NO^{-}_{3}-N$ to $NH^{+}_{4}-N$ was 5∶5) were set. The effects of different irrigation amounts and nitrogen forms on dry matter accumulation (dry weight), yield, water and nitrogen use efficiency and nitrogen metabolism of broccoli were studied. It was shown that under the same nitrogen form, the dry weight, yield, and partial factor productivity from applied nitrogen of broccoli exhibited a trend of increase first and decrease later with the decreasing irrigation amount. Under the same irrigation amount, the glutamine synthetase (GS) activity, glutamate synthase (GOGAT) activity and soluble protein content of broccoli increased with the elevated proportion of $NH^{+}_{4}-N$, while the changes of nitrate reductase (NR) activity was the opposite. All in all, under the experiment condition, the performance of yield, water and nitrogen use efficiency, dry weight of broccoli was the best under W2N3 treatment. In other words, it was a suitable combination for local broccoli production when the irrigation amount was 60% of the maximum field capacity, and the proportion of $NO^{-}_{3}-N$ to $NH^{+}_{4}-N$ was 5∶5.

Key words: broccoli, water use efficiency, nitrogen use efficiency, water and fertilizer management