摘要:构建华北地区设施茄子蒸散量估算模型，可为制定其优化灌溉制度提供理论依据。本研究设灌水定额15 mm（W1）、22.5 mm（W2）、30 mm（W3）和37.5 mm（充分灌溉，CK）4个处理，在设施茄子苗期、开花座果期和成熟采摘期土壤含水率分别达田间持水量的70%、80%和70%时进行灌溉，以保证土壤供水充足。基于修正后的Penman-Monteith方程，通过分析CK处理的作物系数与叶面积指数的关系，建立了基于气象数据与叶面积指数的蒸散量估算模型，利用W1、W2和W3实测蒸散量对其进行验证。结果表明：修正后的Penman-Monteith方程可用于设施参考作物蒸散量的估算，W1、W2和W3蒸散量的实测值与新建模型的模拟值平均相对误差分别为17.81%、18.31%和17.97%。作物系数与叶面积指数呈显著线性关系，可通过叶面积指数确定作物系数。分析W1、W2、W3和CK处理的产量和水分利用效率（WUE）得出，W2与CK产量差异性不显著，而WUE差异性显著，较CK提高31.59%，表明W2兼顾产量和WUE。W2处理下茄子的作物系数，苗期为0.21~0.46，开花座果期为0.62~0.94，成熟采摘期为0.70~0.92。本研究认为，新建模型在估算设施茄子实际蒸散量上具有较好适用性，计算出的作物系数在节水灌溉条件下具有实际应用价值。
关键词:设施茄子/
Penman-Monteith方程/
蒸散量/
估算模型/
作物系数/
灌水定额
Abstract:The theoretical basis of a model for estimation of evapotranspiration of greenhouse eggplants in North China was constructed for the development of optimized irrigation systems.Because irrigation of vegetables in North China has been much higher than crop evapotranspiration, severe deep soil water leakage has occurred, resulting in soil salinization and compaction.This has had a significant impact on the yield and quality of vegetables, resulting in larges waste of water resources.An evapotranspiration model was needed to not only guide irrigation to improve water use efficiency of vegetables, also lay the foundation for the application of agricultural information technology.It can be used to alleviate over-exploitation of groundwater and reduce frequent occurrences of diseases and pests in vegetables due to large amount irrigation.Therefore, it was necessary to establish a model that can accurately simulate vegetable evapotranspiration under greenhouse conditions.In this experiment, the effect of irrigation quota on yield and water use efficiency of eggplant in greenhouse was investigated by setting watering quotas of 15 mm (W1), 22.5 mm (W2), 30 mm (W3) and 37.5 mm (full irrigation quota, CK).The fields were irrigated to ensure sufficient water supply at seeding, flowering and maturity stages, at which the soil moisture contents were kept respectively at 70%, 80% and 70% of field capacity. Based on the modified Penman-Monteith equation and by analysis of relationship between crop coefficient and leaf area index of CK treatment, a model for the evapotranspiration based on meteorological data and leaf area index was established.The model was validated by measured evapotranspiration data under W1, W2 and W3.The results showed that average relative errors between the measured evapotranspiration for W1, W2 and W3 and the simulated values by the model were respectively 17.81%, 18.31% and 17.97%. This showed that the modified Penman-Monteith equation accurately estimated reference crop evapotranspiration under greenhouse conditions.Crop coefficient (Kc) had a significant linear regression with leaf area index (LAI), Kc=0.21 LAI+0.199 1(P < 0.05), indicating that it was possible to determine crop coefficient from leaf area index.The simulated results showed on significant difference in yield (P > 0.05), and significant difference in WUE (P < 0.05) between W2 and CK.WUE of W2 was 31.59% higher than that of CK, indicating that W2 addressed both yield and WUE.Crop coefficients of eggplants at seedling stage and flowering to fruiting period and ripening stage under W2 treatment were respectively 0.21-0.46, 0.62-0.94 and 0.70-0.92.The study suggested that the new model was applicable in estimating actual evapotranspiration of facility eggplants.It calculated crop coefficient that was of practical value in water-saving irrigation.The research was significant for guiding agricultural precision irrigation.
Key words:Facility eggplant/
Penman-Monteith equation/
Evapotranspiration/
Estimation model/
Crop coefficient/
Irrigation quota
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