Development of an Automatic Irrigation Method Using an Image-Based Irrigation System for High-Quality Tomato Production

In this study, we developed an automatic irrigation method using an image-based irrigation system for high-quality tomato production in a greenhouse by investigating effects of a diurnal periodic cycle of irrigation on the photosynthesis, growth, yield, and fruit quality of tomatoes. The diurnal periodic cycle in a moderate wilting-full recovery treatment (MR) with a medium threshold value was more frequent than that in a severe wilting-full recovery treatment (SR) with a high threshold value. Mean daily maximum wilting ratios for MR and SR were 7.2% and 11.3%, respectively, when wilting ratios were set to threshold values of 7% and 14%, respectively. Total irrigation amounts in MR and SR were similar and lower than that in the untreated control. Net photosynthetic rate decreased under water stress, with values in MR being higher than that in SR, and recovered rapidly to more than 90% of its maximum value following irrigation. Plant growth and fruit yield per plant in MR and SR were lower than that in the control. Water stress treatment could improve fruit quality when it commenced at the anthesis stage or early fruit development stage. Total irrigation amount was a more important parameter than the threshold value for controlling the growth, yield, and fruit quality of tomatoes.

Automated summary

In this study, an automatic irrigation method using image-based system was developed to enhance high-quality tomato production in a greenhouse. The effects of a diurnal periodic cycle of irrigation on various aspects of tomatoes were investigated. The results showed that the frequency of diurnal periodic cycle was higher in the moderate wilting-full recovery treatment compared to the severe wilting-full recovery treatment. Moreover, total irrigation amount was found to be a more important factor than the threshold value in controlling the growth, yield, and fruit quality of tomatoes.