Greenhouse cucumber production using sensor-based irrigation

摘要

Cucumber is the most important vegetable produced in the U.S. Virgin Islands. Crop production is performed outdoors, with no information available regarding cultivation in a closed environment using precision irrigation to increase yield and save water. This study evaluated greenhouse production of different slicing cucumbers under increasing substrate volumetric water contents (VWC) to trigger irrigation automatically based on plant demand. Experiments were conducted in Fall 2016 and Spring 2017. Wetested four cucumber varieties ('Boa', 'Corinto', 'Marketmore 76' and 'Verdon') and three substrate VWC to trigger irrigation (0.3, 0.4 and 0.5 m3/m3), on a split-plot design with three replications. Plants were transplanted into 9.45-L pots spaced 0.46x 1.22 m, trained on a vertical plastic line, and fertigated with 5N-11P-26K hydroponic fertilizer (Peter's Professional; Everris, Geldermalsen, The Netherlands) and calcium nitrate. Irrigation was performed on-demand using one substrate moisture sensorper experimental unit formed by four pots. The irrigation system applied water automatically when the VWC dropped below the set thresholds. Sensor-based irrigation was effective to water the plants. The number of irrigation events and leaf anthocyanin content differed on both seasons. Total yield and total number of fruit/plant responded to increases in VWC and varieties (P<0.05). 'Corinto' cultivated with VWC 0.5 m3/m3 resulted in the highest yield at 57,445 kg/ha (P=0.00269). Marketable yield, fruitwidth and fruit hardness were variety-dependent. Fruit weight and length, leaf chlorophyll, plant growth index and fruit soluble solids content were influenced by the different seasons and varieties (P<0.05). 'Corinto' consistently showed higher yield inall VWCs used to trigger irrigation, producing longer and more fruit than the other varieties, being a promising cultivar for greenhouse cucumber production using sensor-based irrigation in the U.S. Virgin Islands.