Combined Effects of Film Mulching and Water-controlled Drip Irrigation on Yield and Quality of Facility-cultivated Tomato in Ningxia

Abstract

【Background】 Tomato is a vegetable grown widely across Ningxia in greenhouses with the soil mulched. Drip irrigation is the main irrigation for greenhouse crops, but excessive irrigation is common resulting in not only water waste but also environmental contamination due to agrochemicals leaching. Increasing water use efficiency and reducing detrimental impact of the mulching film is hence critical to sustaining tomato production in Ningxia. 【Objective】 The purpose of this study was to find an optimal drip-irrigation scheduling and film mulching in attempts to provide guidance for improving water use efficiency while in the meantime increasing yield of the greenhouse tomato in Ningxia. 【Method】 A two-year experiment was conducted in a solar greenhouse with the soil either not mulched (M) or mulched (NM) with plastic film. Added to these were three irrigation levels by keeping the soil moisture at 100% (W1), 80% (W2) and 70% of the field capacity respectively, with the irrigation used by local farmers (123% of the field capacity) taken as the control (CK). 【Result】 It was the film much rather than the irrigation amount that affected the growth of plant height and stem diameter from seedling stage to flowering and fruit setting stage at significant level (P<0.01). With an increase in irrigation amount, the tomato yield increased first followed a decline. The yield and water use efficiency of W2M were 89 844.8.8 kg/hm2 and 502.5 kg/(hm2·mm) respectively, up 21.4% and 63.7% respectively from CKM. Compared with not mulching, mulching increased the average yield by 18.1%, reductive vitamin C and soluble solid content by 28.9% and 22.8% respectively, all at significant level (P<0.05). The combined effect of water control and film mulch on reductive vitamin C, soluble solids and total soluble sugar was significant at P<0.01, and the effect of film mulching on titratable acid and sugar acid ratio was significant at P<0.05. Compared with CK, W3 increased the total soluble sugar content and the sugar acid ratio by 4.2%~8.2% and 48.9% respectively, both at significant level (P<0.05), while reducing the titratable acid content by 37%. W2M increased the soluble solid content and the sugar acid ratio most, by 12.3% and 8.5% respectively, compared to CK. Film mulching also affected soluble sugar and soluble acid content at significant level (P<0.05). 【Conclusion】 Our two-year experiment showed that keeping the soil moisture not exceeding 80% of the field capacity using drip irrigation with the soil mulched was most effective to increase yield and quality of the greenhouse tomato in Ningxia.

Keywords

• film mulching
• drip irrigation
• tomato
• yield and fruit quality
• greenhouse