加气灌溉改善大棚番茄光合特性及干物质积累

为揭示不同加气灌溉参数对作物光合特性及干物质积累的影响规律，以番茄为研究对象，研究了不同土壤加气量与加气深度组合对番茄光合作用、叶绿素含量、干物质积累及产量的影响。结果表明，对番茄根区土壤加气可显著提高叶片叶绿素含量和气孔导度，增强光合作用，增加干物质积累及产量。随加气量的升高，大棚番茄净光合速率总体上呈先升高后降低的趋势。15和40 cm滴管带埋深下，标准加气量（49.4 L/m2）下2次测定净光合速率平均较不加气处理升高21.4%和65.0%。滴灌带埋深为15 cm时，叶绿素含量、干物质积累量及产量随加气量的升高呈先升高后降低趋势，标准加气量下较不加气处理分别提升38.0%、55.4%和59.0%，滴灌带埋深为40 cm时随加气量的升高呈持续升高趋势，1.5倍标准加气量（74.2 L/m2）处理较不加气处理分别提升33.7%、36.2%和105.4%。综合考虑，当滴灌带埋深为15 cm时，宜采用标准加气量作为加气标准，而埋深为40 cm时，最佳加气量为1.5倍标准加气量。

Aerated irrigation improving photosynthesis characteristics and dry matter accumulation of greenhouse tomato

It is well known that most plants’ roots require an adequate and continuous supply of oxygen in soil to respire, grow, develop, and function normally. Industrial agriculture has developed rapidly but is accompanied by excessive irrigation and fertilization, minimal tillage and agricultural machinery driving over the soil. All these farming activities can result in soil compaction. In compacted soil, the increase in soil bulk density and the accompanying decrease in porosity can hinder the exchange of oxygen, carbon dioxide and other gases between the atmosphere and the soil, thereby causing hypoxic stress in plant roots. In addition to compaction, some natural factors, such as extraordinarily high groundwater table, long-term rainfall and tillage under clay or clay loam conditions, can often lead to soil oxygen content reduced, which limits crop yield and quality improvement. Tomato plants (Solanum lycopersicum) are one of the most vulnerable mesophytes to hypoxia in the root environment. Soil aeration has been found to be very useful in overcoming problems associated with hypoxia in the root-zone of irrigated crops including tomato, cotton, cucumber and zucchini. Over a range of soil water contents and soil types, the performance of crops can be improved under oxygen-deficient conditions. It is hypothesized that varying the aeration volume and burial depths of drip irrigation tubes (aeration position) would result in the different soil air environment in the root-zone. To date, there are no reports in the literature which specifically examined the sensitivity of tomato plants to soil aeration volume and burial depths of drip irrigation tubes in Lou soil, and the effect on the photosynthetic characteristics and dry matter accumulation. The experiments were conducted in a greenhouse at Yangling (E108°02′, N34°17′), Shaanxi, between October, 2014 and May, 2015. The tested variety of tomato was Fenyuyanggang (New Horizon Facilities Agricultural Development Co. Ltd., Northwest A&F University, China). Air was used for soil aeration, and the soil for the test was a silty clay loam (soil order was Inceptisol based on the USDA (United States Department of Agriculture) soil taxonomy). The volume of air in each plot was injected into the drip tubing via a manifold connected to the air compressor. The experiment was designed to study the responses of photosynthetic characteristics, chlorophyll content and dry matter accumulation of greenhouse-produced tomato to 4 aeration volumes in combination with 2 depths of drip-tubing placed in the soil. The drip irrigation placement depths were respectively 15 and 40 cm below the surface of the ridge. Artificial aeration treatments were 0, 24.6, 49.4 and 74.2 L/m2, respectively. Results showed that drip tubing placement and artificial aeration treatments significantly affected photosynthetic characteristics, chlorophyll content and dry matter accumulation. The changing trend of net photosynthetic rate showed an increase at first and then a decrease with the increase of aeration volume at both 15 and 40 cm depth of the tube. Chlorophyll a and dry matter accumulation of tomato also showed an increase firstly and then a decrease with the increase of aeration volume at 15 cm depth of the tube. However, chlorophyll a and dry matter accumulation increased with the increasing of the volume of aeration at 40 cm depth of the tube. Synthesizing each kind of situation, both 15 and 40 cm depth of the tube could apply to artificial soil aeration. The optimum artificial aeration volume was 49.4 L/m2 at the 15 cm deep of the tube. However, at the 40 cm deep of the tube, 74.2 L/m2 aeration volume was better than the other treatments. For the observed responses, the information on how the tomato adapts to artificial soil aeration will provide guidance for field production practices as well as indications of possible mechanisms.