地膜覆盖和施氮对菜地CO2通量的影响

为了探讨地膜覆盖和不同施氮处理对菜地生态系统CO₂净交换通量（Net CO₂ Ecosystem Exchange，简称NEE）、生态系统呼吸通量（Ecosystem Respiration，简称ER）及总初级生产力（Gross Primary Productivity，简称GPP）的影响，以辣椒-萝卜轮作菜地为研究对象，采用静态明/暗箱-气相色谱法，进行了为期1 a（2014年5月-2015年4月）的田间原位观测.试验设置8个处理，分别为常规无氮（CN0）、覆膜无氮（MN0）、常规低氮（CN1）、覆膜低氮（MN1）、常规中氮（CN2）、覆膜中氮（MN2）、常规高氮（CN3）、覆膜高氮（MN3）.结果表明，辣椒季累积NEE最大值分别为CN3和MN3处理下的-30.96和-29.83 t·hm^-2，累积ER排放量最大值分别为CN1和MN1处理下的40.18和39.16 t·hm^-2，累积GPP最大值分别为CN3和MN3处理下的70.60和68.61 t·hm^-2；萝卜季累积NEE最大值分别为CN3和MN3处理下的-22.25和-24.88 t·hm^-2，累积ER排放量最大值分别为CN2和MN2处理下的17.00和19.43 t·hm^-2，累积GPP最大值分别为CN3和MN3处理下的37.92和43.80 t·hm^-2.在两个生长季中，覆膜及覆膜和施氮的交互作用只对辣椒季中ER有显著影响，对于NEE和GPP均无显著影响（p>0.05）；施氮显著提高了菜地生态系统NEE和GPP而降低了辣椒季ER（p<0.05），并且这种增加或降低效应随着施氮量的提高而逐渐增强.本研究中菜地呈现碳汇并随着施氮水平的提高碳汇逐渐增强，而覆膜对CO₂固定无显著影响，表明常规高氮的农田管理措施能够提高西南地区代表性的辣椒-萝卜轮作菜地的固碳潜力，对该地区农田生态系统碳的源/汇功能具有一定的参考意义.

Effects of plastic film mulching and nitrogen fertilizer application on CO2 fluxes from a vegetable field

In order to investigate the effects of plastic film mulching and nitrogen application on carbon fluxes from vegetable fields, net CO₂ ecosystem exchange (NEE), ecosystem respiration (ER) and gross primary productivity (GPP) were monitored in a hot pepper (Capsicum annuum)-radish (Raphanus sativus) rotation in southwest China for one year between May 2014 to April 2015 by using static transparent/opaque chamber method. Plastic film mulching (M) and no mulching (C) were installed as main treatments, and four N application rates as sub-treatments were arranged in each main treatment. Thus the following eight field treatments were included:MN0 and CN0 (no-N application control), MN1 and CN1 (150 or 100 kg·hm^-2 for hot pepper or radish), MN2 and CN2 (300 or 200 kg·hm^-2 for hot pepper or radish), MN3 and CN3 (450 or 300 kg·hm^-2 for hot pepper or radish season). The results showed that in hot pepper season, the maximum cumulative NEE was -30.96 and -29.83 t·hm^-2 under CN3 and MN3 treatments, the maximum cumulative ER was 40.18 and 39.16 t·hm^-2 under CN1 and MN1 treatments, and the maximum cumulative GPP was 70.60 and 68.61 t·hm^-2 under CN3 and MN3 treatments, respectively. In radish season, the maximum cumulative NEE was -22.25 and -24.88 t·hm^-2 under CN3 and MN3 treatments, and the maximum cumulative ER in radish season was 17.00 and 19.43 t·hm^-2 under CN2 and MN2, and the maximum cumulative GPP was 37.92 and 43.80 t·hm^-2 under CN2 and MN2, respectively. During the two growing seasons, film mulching had significant effect on ER in hot pepper season, but had no significant effect on NEE and GPP (p>0.05); nitrogen application significantly increased NEE and GPP in hot pepper and radish seasons, but decreased ER in hot pepper season (p<0.05), and these effects of increase or decrease gradually strengthened with the increase of nitrogen application. Vegetable field acted as a carbon sink and increased with the increase of nitrogen application, while film mulching had no significant effect on CO₂ fixation, indicating that high nitrogen application with no mulching practice can increase the carbon sequestration potential in hot pepper and radish rotation field in Southwest China.