| Abstrak/Abstract |
Effects of corn steep liquor (organic fertilizer, OF) and conventional chemical fertilizer (CF)
on the growth and yield of bok choy (Brassica rapa var. chinensis) in summer and autumn hydroponic
growing systems were compared. When OF and CF were applied with the same amount of total
nitrogen in summer cultivation, there was no significant difference between yields; however, the
growth rate in OF was slower than in CF. When OF was applied with twice the amount of nitrogen
in CF (OF2), bok choy growth and yield were significantly inhibited in summer cultivation, likely
owing to dissolved oxygen deficiency and different rates of nitrification and nitrogen absorbance by
the plant root. Although the contents of potassium, calcium, and magnesium in bok choy showed no
difference among the three treatments in both cultivation seasons, the carbon/nitrogen ratio tended
to be higher in OF and OF2 than in CF. Lower nitric acid and higher ascorbic acid content was found
in OF and OF2 than in CF. Overall, our results suggest that a comparable yield is expected by using
the same nitrogen amount with a conventional recipe of chemical fertilization in autumn cultivation.
However, further improvement of hydroponic management is needed in summer cultivation. |
