Mechanisms of environmental factors affecting uptake and utilization of N and P by vegetable crops

IPNI-2010-CHN-ZJ25

16 Feb 2011

2010 Annual Interpretive Summary

Effects and Mechanisms of Environmental Factors on Uptake and Utilization of Nitrogen and Phosphorus in Vegetable Crops, 2010

Vegetables are characterized with both high harvest index and high nutritional requirements. Fertilization is a key agricultural measure for vegetable production; however, over-fertilization has been very common in China. Excessive fertilization leading to low fertilizer use efficiency can lead to soil salinization, nutrient imbalance, and nutrient loss, which decrease vegetable productivity and increase the risk of environmental pollution. Intensively managed vegetable systems with high fertilizer input were selected to study the effects of dominant environmental factors (moisture, light, and temperature) on the transformation of N and P in soils, and uptake and utilization of N and P, to provide the basis and technical support needed to improve fertilizer use efficiency in these fields.

In 2010, results showed that: Net N mineralization (Nmin), microbial activity, and microbial biomass were significantly higher in the dry-wet (DW) treatment than in the 30% and 75% water holding capacity (WHC) treatments. The higher water content (75% WHC) treatment had higher Nmin, microbial activity, and biomass than the lower water content (30% WHC). Multivariate analyses of community-level physiological profile (CLPP) and phospholipid fatty acid (PLFA) data indicated that soil moisture regime had a significant effect on soil microbial community functional and structural diversity. Soil moisture influenced N availability mainly by changing the microbial biomass and activity. The elevated CO2 treatment significantly improved root hair development and elongation, and increased indole acetic acid (IAA) concentration in plant tissues, and ethylene release. These responses resulted in root growth improvement and root hair development and elongation, which in turn enhanced plant nutrient uptake. Appropriate N level improved plant growth by enhancing the antioxidant defense capacity, which prevents active oxygen accumulation under adverse environmental conditions. Zhejiang-25