[Effects of organic fertilizer on soil environment and yield of tomato under year-round cultivation].

The early-spring and autumn-winter tomato in greenhouse is the main planting patterns of protected vegetable in North China. Taking the customary fertilization amount of farmers under this planting pattern as control (CK, 100% chemical fertilizer), six organic fertilizer replacing chemical fertilizer treatments were set, namely, 15% (T), 30% (T), 45% (T), 60% (T), 75% (T), 100% organic fertilizer (T), to examine the replacing effects on soil environment and tomato yield. The results showed that soil bacteria increased with increasing organic fertilizer amount, the actinomycetes wers up to 12.

[Application effects of biogas slurry partly substituting for chemical fertilizer on autumn tomato production in winter-solar greenhouse].

To explore the effects of biogas slurry coordinating chemical fertilizer on growth promotion of tomato, we used three kinds of typical biogas slurry as concentrated nutrient solution, respectively fermented from raw duck manure, pig manure, cow dung, while urea, monocalcium phosphate and potassium sulphate as auxiliary nutrition to balance the nutrient difference between different dilution ratios of biogas slurry. The results showed the biogas slurry partially substituting chemical fertilizer could significantly improve soil fertility, including available nitrogen, phospho-rus, and potassium. As for water soluble calcium, magnesium, iron, manganese and zinc in soil, biogas slurry application could activate their availability, with the magnitude of such effects depended on the fermentation level of raw materials and dilution ratio.

[Effects of purified humic acid on the growth and nitrogen metabolism of cucumber seedlings under nitrogen stress.].

To investigate the effects of purified humic acid (PHA) on the growth and nitrogen metabolism of cucumber under different levels of nitrogen stress and to explore the mechanism of PHA's alleviation on abiotic stress, we examined the effects of PHA on 'Xintaimici' cucumber growth and nitrogen metabolism under low nitrogen (1.0 mmol·L NO) stress and high nitrogen (101 mmol·L NO) stress in hydroponics compared with normal level (11 mmol·L NO). The results showed that the growth of cucumber seedlings was inhibited under nitrogen stress treatments.

[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) on growth and nutrient absorption of cucumber seedlings under low nitrogen stress (1 mmol·L NO) 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.