土壤盐分与施氮量交互作用对葵花生长的影响

    Interactive effect of salinity and nitrogen application on sunflower growth

    • 摘要: 为了研究盐分和氮素交互作用对葵花生长的影响,采用双因素随机区组设计在内蒙古河套灌区义长试验站开展微区试验,观测指标包括葵花的出苗率、成熟期株高、叶面积、地上部分干物质量、吸氮量和产量等。试验结果表明土壤0~20 cm初始盐分质量分数是影响葵花生长的主要限制因素,将土壤0~20 cm初始盐分质量分数由<0.25%(S1)增加至1%以上(S4)能够使不同施氮水平下葵花出苗率、株高、叶面积、干物质量和产量的均值分别降低72.0%、40.0%、58.5%、41.7%和76.41%,并且在不同的施氮量水平下,葵花的出苗率均与土壤0~20 cm初始盐分质量分数呈线性下降的关系。当土壤盐分水平为>0.5%~1.0%(S3)时,将施氮量水平由N1(90 kg/hm2)增加至N3(180 kg/hm2)能够使葵花出苗率、株高、叶面积、干物质量和产量分别增加16.7%、35.6%、39.1%、69.9%和80.0%;当土壤盐分水平大于1.0%(S4)时,将施氮量水平由N1增加至N3能够使上述5项指标分别增加45.4%、20.5%、47.4%、42.7%和76.2%。但是当土壤初始盐分质量分数小于0.5%时,增施氮肥对上述5项指标的影响效果降低。此外,尽管葵花的吸氮量随氮肥施入量的增加而增加,但是葵花对氮肥的利用效率还与受到土壤盐分水平的影响,当土壤0~20 cm初始盐分质量分数小于0.5%时,葵花对氮肥的利用率随施氮量的增加而降低,而当土壤0~20 cm初始盐分质量分数大于0.5%时,增施氮肥有助于提高葵花对氮肥的利用率。综合考虑收益、环境影响以及农业灌溉措施的等因素,建议适合河套灌区的合理施氮水平为135 kg/hm2。

       

      Abstract: Abstract: For understanding the interaction effect of salinity and nitrogen on sunflower growth, complete block design experiments were conducted in Hetao Irrigation District of China, and the observation index included sunflower emergency rate, plant height, leaf area, above-ground dry weights, nitrogen uptake, and yield. To be more specific, 14 days after sowing, we observed the number of sunflower seedlings daily, and their emergence rate was calculated by dividing the number of seedlings 14 days after sowing by the total seeds of sunflowers. Furthermore, the leaf area was measured by a portable leaf area meter (YMJ-C, TuoPu, China), and plant height was measured by tape. After the sunflowers were harvested, sunflower seeds were weighed after air-drying (moisture <8%), and then sieved to remove debris; two uniform plants from each lysimeter were manually uprooted at maturity for nitrogen uptake analysis and determination of biological yield. These plants were partitioned into flower disks, stems, leaves, seeds, and roots, were weighed after drying at 70℃ to a constant weight, and the biological yield of each component was recorded. In order to determine nitrogen uptake, samples of each plant part were grinded and screened through a 0.5 mm sieve. Total nitrogen concentration was determined by the micro-Kjeldahl method, and the ratio between seed yield and nitrogen application was selected as the evaluation indictor for nitrogen use efficiency of each micro-plot. The experimental results indicated that soil salinity significantly affects sunflower growth, and that the soil salinity level of S4( >1%) could reduce 72.0% emergency rate, 40.0% plant height, 58.5% leaf area, and 76.4% yield related to the S1(0-0.25%) salinity level. Furthermore, sunflower emergence has a negative linear relationship with soil salinity in different nitrogen application rates. A nitrogen fertilizer application could alleviate the adverse effects of salinity on sunflower growth to some extent. To be more specific, at the S3 salinity level (0.5%-1.0%), increasing the nitrogen application rate from N1(90 kg/hm2) to N3(180 kg/hm2) could increase the emergence rate, plant height, leaf area, dry matter amount, and seed yield to 16.7%, 35.6%, 39.1%, 69.9%, and 80.0% respectively. Furthermore, when the salinity level was above 1.0%, these 5 indicators increased 45.4%, 20.5%, 47.4%, 42.7%, and 76.2% respectively. However, this relationship was not obvious when the soil salt content was smaller than 0.5%. In addition, although sunflower nitrogen uptake increased with nitrogen application, the nitrogen use efficiency (NUaE) was also affected by the soil salinity level. More exactly, when the soil salt content was smaller than 0.5%, the NUaE decreased with the nitrogen application, and the opposite phenomenon occurred when the soil salt content was larger than 0.5%. Moreover, taking economic profits, environment production, and irrigation schedule into consideration, we suggested the optimal nitrogen application rate for sunflower growth in the Hetao Irrigation District was 135 kg/hm2.

       

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