[Effects of purified humic acid on growth and nutrient absorption of cucumber (Cucumis sativus)seedlings under low nitrogen stress.]

Taking 'Xintaimici' and 'Jinyou 1' as experimental cucumber cultivars, this paper studied the effects of watering purified humic acid (PHA) at different levels (0, 50, 100, 150, 200 mg·L-1) on growth and nutrient absorption of cucumber seedlings under low nitrogen stress (1 mmol·L-1 NO3-) in sand culture pots. The results showed that, under low N condition, PHA could significantly increase the total root length, root surface area, root tip number and root volume of cucumber seedlings, and promote plant height, stem diameter and leaf area. Proline and soluble sugar contents in cucumber leaves were significantly increased by PHA. The absorption of N, P, K, Ca, Mg, Fe in cucumber seedlings was promoted. According to the response of the two cucumber cultivars to PHA under low N stress, some traits of two cultivars showed different sensitivity to PHA level. The comprehensive analysis of the above results inferred that the PHA level from 100 mg·L-1 to 150 mg·L-1 could significantly enhance the growth and nutrient absorption of cucumber seedlings.