关键词: 小麦, 增铵营养, 净光合速率, 可溶性糖, 硝酸还原酶

Abstract: The study on the effects of delaying first feeding time on the foraging, survival, and growth of Acipenser schrenckii larvae showed that the larvae opened their mouth at the age of 6 days, and started initial foraging at the age of 7 days. The yolk was absorbed completely at the age of 10 days, and the larvae entered into the point-of-no-return (PNR) period at the age of 16-17 days if they couldn’t get exterior nutrition, suggesting that the point-of-no-return (PNR) of A. schrenckii larvae was at the age of 16 days. The survival rate of the larvae decreased with the delay of first feeding time. After the age of 6 days, the survival rate of the larvae was above 60% if the first feeding was delayed less than 7 days, while dropped to 40%, 10% and 0 if the feeding was delayed 8-10, 11, and more than 12 days, respectively. The larvae length and weight increased if the first feeding was delayed within 4 days, but dropped if the feeding was delayed more than 4 days. No significant difference was observed in the larvae length and weight between 8 days delayed feeding and the control, but both of these two indices were significantly lower if the first feeding was delayed more than 9 days, compared with the control. The optimum first feeding time of A. schrenckii larvae was 9-10 days after hatching.

Key words: Wheat, Enhanced ammonium nutrition (EAN), Net photosynthetic rate, Soluble sugar, Nitrate reductase (NR)