向日葵和马铃薯间作条件下氮素的吸收和利用

间套作不但能提高作物产量和资源利用效率,也是有效降低土壤风蚀的重要措施。明确间套作体系中氮素竞争与互补机理,提高氮素利用效率对区域农业可持续发展有着重要意义。该研究于2010年和2011年在内蒙古武川进行了大田试验,利用半微量凯氏定氮方法测定植株各器官氮素含量和氮吸收量,探讨间作中作物对氮素吸收和利用的特征。结果表明,从系统角度出发,向日葵和马铃薯间作系统的氮吸收当量比(NER)为0.95～1.02,差异不显著,这种间作模式对作物氮的吸收效率没有影响。从作物角度出发,间作没有显著提高向日葵的氮素吸收和利用效率,却降低了系统中马铃薯的氮素吸收和利用效率。间作中,向日葵氮偏吸收当量比为0.53～0.74,大于其种植比例(50%),说明间作向日葵具有显著的氮素竞争和吸收优势;而马铃薯氮偏吸收当量比为0.28～0.42,低于其在间作中所占的比例(50%),处于显著劣势。间作马铃薯产量(鲜薯质量,80%含水率)的氮素生理利用效率(NPE)为249.2g/g,略低于单作(269.8g/g),其中4行马铃薯:4行向日葵(4P:4S)间作马铃薯的NPE为238.2g/g,显著低于单作。4P:4S间作向日葵产量(籽粒质量,12%含水率)的NPE为30.1g/g,高于单作(25.9g/g)和2行马铃薯:2行向日葵(2P:2S)间作的NPE(22.8g/g)。在4P:4S间作模式中,向日葵的NPE有所提高,作为代价,降低了马铃薯的NPE。间作中马铃薯的收获指数HI(0.83)低于单作(0.87),间作向日葵的HI(0.40)高于单作的HI(0.33)。间作作物NPE的变化主要受作物收获指数HI的影响。

Nitrogen uptake and utilization in sunflower and potato intercropping

Abstract: Intercropping not only improves crop yield and resource use efficiency, but also reduces soil-wind erosion as a biological hedge in winter periods. It is important to quantify the mechanism of nitrogen competition and affiliation, thereby to enhance nitrogen use efficiency and agricultural sustainability. We explored nitrogen uptake and utilization in sunflower and potato intercropping systems by field experiments, which were carried out in 2010 and 2011 in Wuchuan, Inner Mongolia. The plant nitrogen content for different organs and nitrogen uptake was measured by using the Semi-micro Kjeldahl method. The results showed that the sunflower and potato intercropping systems did not significantly improve crop nitrogen uptake comparing to the monocultures at system level. The nitrogen equivalent ratios (NER) for uptake ranged from 0.95 to 1.02, and were not significantly different between intercropping configurations. At crop level, intercropping did not reduce nitrogen uptake and utilization efficiency of sunflowers, but reduced that of the potato. Intercropped sunflowers showed a significant advantage in nitrogen competition and uptake, in which the partial NER, ranged from 0.53 to 0.74, was higher than its relative density (50%), while the intercropped potato showed a significant disadvantage, which the partial NER (ranged from 0.28 to 0.42) was much lower than its relative density (50%). Nitrogen physiological use efficiency (NPE) yield produced per unit N uptake of intercropped potato (fresh tuber weight with 80% water content) was 249.2 g/g, slightly lower than that of the sole system (269.8 g/g). In a four rows of potato and four rows of sunflower (4P:4S) intercropping system, the NPE of intercropped potato was 238.2 g/g, significantly decreased compared to that of the sole potato. The NPE of sunflower (grain with 12% water content) in 4P:4S intercropping (30.1 g/g) was 16.2% greater than that of the sole sunflower (25.9 g/g), also higher than that in two rows potato and two rows sunflower (2P:2S) intercropping (22.8 g/g). The NPE of 4P:4S intercropped sunflower increased at the expense of decreasing NPE of potato. The harvest index (HI) of intercropped potato (0.83) was lower than that of the monoculture (0.87); however, the HI of intercropped sunflower (0.40) was significantly higher than that of sole sunflower (0.33). The change of crop NPE was mainly affected by the crop harvest index.