Rapid Estimation of Crop Water Stress Index on Tomato Growth

The goal of this research is to use a WORKSWELL WIRIS AGRO R INFRARED CAMERA (WWARIC) to assess the crop water stress index (CWSI_W) on tomato growth in two soil types. This normalized index (CWSI) can map water stress to prevent drought, mapping yield, and irrigation scheduling. The canopy temperature, air temperature, and vapor pressure deficit were measured and used to calculate the empirical value of the CWSI based on the Idso approach (CWSI_Idso). The vegetation water content (VWC) was also measured at each growth stage of tomato growth. The research was conducted as a 2 × 4 factorial experiment arranged in a Completely Randomized Block Design. The treatments imposed were two soil types: sandy loam and silt loam, with four water stress treatment levels at 70-100% FC, 60-70% FC, 50-60% FC, and 40-50% FC on the growth of tomatoes to assess the water stress. The results revealed that CWSI_Idso and CWSI_W proved a strong correlation in estimating the crop water status at R² above 0.60 at each growth stage in both soil types. The fruit expansion stage showed the highest correlation at R² = 0.8363 in sandy loam and R² = 0.7611 in silt loam. VWC and CWSI_W showed a negative relationship with a strong correlation at all the growth stages with R² values above 0.8 at p < 0.05 in both soil types. Similarly, the CWSI_W and yield also showed a negative relationship and a strong correlation with R² values above 0.95, which indicated that increasing the CWSI_W had a negative effect on the yield. However, the total marketable yield ranged from 2.02 to 6.8 kg plant^-1 in sandy loam soil and 1.75 to 5.4 kg plant^-1 in silty loam soil from a low to high CWSI_W. The highest mean marketable yield was obtained in sandy loam soil at 70-100% FC (0.0 < CWSI_W ≤ 0.25), while the least-marketable yield was obtained in silty loam soil 40-50% FC (0.75 < CWSI_W ≤ 1.0); hence, it is ideal for maintaining the crop water status between 0.0 < CWSI_W ≤ 0.25 for the optimum yield. These experimental results proved that the WWARIC effectively assesses the crop water stress index (CWSI_W) in tomatoes for mapping the yield and irrigation scheduling.