Abstract:

Soil organic carbon (SOC) is not only the foundation of crop growth and development, but also an important terrestrial carbon sink, which plays a key role in global carbon balance. From 2017 to 2020 at the eastern foot of Helan mountain in Ningxia, the stationing method of checkerboard and GPS to locate the position were used in order to study the effects of SOC on growth and water use of maize in the maize farmland ecosystems. The results showed that the net photosynthetic rate of maize increased, and the transpiration rate decreased at the early stage, and then increased with the increase of SOC. Positive correlations were found between stomatal conductance and SOC, and intercellular CO₂ concentration was negatively related to SOC. With the increase of SOC, leaf water used efficiency fluctuated upward at jointing, big flare stage and maturity while chlorophyll fluctuated upward between the jointing and big flare stages. With the increase of SOC, the ear length, ear diameter, grain number per ear, ear mass, root, stem, leaf and ear dry weight of maize increased. As the SOC increased from 2.45 g∙kg^-1 to 13.52 g∙kg^-1, ear length and ear diameter increased by 44.3% and 21.0%, respectively; ear number and ear mass increased by 49.3% and 70.5%, respectively; root, stem, leaf and ear dry weight increased by 61.8%, 30.2%, 27.1% and 19.0%, respectively. The above analyses showed that the maize yield reached a higher range of 15.5-15.7 t∙hm^-2, when SOC was 10.5-12.0 g∙kg^-1. When SOC was higher than 12.0 g∙kg^-1, the yield decreased with the SOC. When SOC was higher than 11.5 g∙kg^-1, the water use efficiency of maize decreased with the increased of SOC. It is concluded that the SOC kept at 10.0-12.0 g∙kg^-1 is a reasonable threshold in the ecological experimental study area at the eastern foot of Helan Mountain.

Key words: soil organic carbon, carbon sink, farmland ecosystems, growth and development, maize, water use

摘要：

土壤有机碳是作物生长发育的根基,也是陆地重要的碳汇,在全球碳平衡中起着关键的作用。2017-2020年选择宁夏贺兰山东麓生态试验研究区玉米（Zea mays L.）农田生态系统,采用棋盘式区域布点,GPS定点标记并采集样品,开展土壤有机碳对玉米生长发育及水分利用的影响研究。研究表明玉米净光合速率随土壤有机碳的增加而升高,蒸腾速率随土壤有机碳的增加表现为先减后增;气孔导度与土壤有机碳呈正相关关系,胞间CO₂浓度与土壤有机碳呈负相关关系;叶片水分利用效率在拔节期、大喇叭口期和成熟期,随土壤有机碳的增加而波动增加;叶绿素在拔节期与大喇叭口期,随土壤有机碳的增加而波动升高。玉米穗长、穗粗,穗粒数、穗质量,根、茎、叶、穗干质量,分别随土壤有机碳的增加而增加。土壤有机碳从2.45 g∙kg^-1增加到13.52 g∙kg^-1,玉米穗长与穗粗分别增加44.3%与21.0%,穗粒数与穗质量分别增加49.3%与70.5%,根、茎、叶、穗干质量分别增加61.8%、30.2%、27.1%、19.0%。土壤有机碳为10.5-12.0 g∙kg^-1时,玉米产量达到较高的范围15.5-15.7 t∙hm^-2;土壤有机碳超过12.0 g∙kg^-1,产量呈现下降趋势。土壤有机碳超过11.5 g∙kg^-1,玉米水分利用效率呈现下降。贺兰山东麓黄河灌溉生态试验示范区,农田土壤有机碳保持10.0-12.0 g∙kg^-1,能够有效促进玉米生长发育,提高产量及水分利用,是较为合理的阈值范围。

关键词: 土壤有机碳, 碳汇, 农田生态系统, 玉米, 生长发育, 水分利用