The Effect of Irrigation and Vermicompost Applications on the Growth and Yield of Greenhouse Pepper Plants

In agricultural practice, improper irrigation levels and excessive fertiliser use negatively impact water resources and soil properties, respectively. This experiment aims to determine the effects of varying irrigation levels and vermicompost doses on the growth, quality, and productivity of pepper plants grown under polycarbonate greenhouse conditions. To achieve this objective, different irrigation levels (IL) of IL100 (100% full irrigation), IL75 (75%), IL50 (50%), and vermicompost doses (VD) of VD0 (0%), VD10 (10%), and VD20 (20%) were tested. The highest irrigation level was in the IL100–VD10 treatment, which also had the highest water consumption (ET) in the 27.8 L pot−1. By comparison, the IL50–VD0 treatment had the lowest irrigation level in the 15.4 L pot−1, representing nearly 55.4% of the maximum irrigation water amount. The findings showed that the irrigation levels and vermicompost doses had a significant impact on plant growth, quality, and fruit yield parameters. Accordingly, the irrigation levels and vermicompost doses had significant effects on the studied plant growth parameters (stem diameter, plant height, number of leaves, stem fresh weight, stem dry weight, root fresh weight, and root dry weight). Similar effects were also observed on the fruit quality parameters (fruit width, fruit length, fruit weight, fruit flesh thickness, pH, titratable acidity (TA), total soluble solids (TSS), chrome, and hue). This study found that the highest total yield (164.5 g pot−1), marketable yield (149.8 g pot−1), total water use efficiency (6.1 g L−1), and marketable water use efficiency (5.6 g L−1) were obtained at the 100% irrigation level. However, similar results were observed at the 75% irrigation level and a 20% vermicompost dose, where the total water use efficiency was 5.9 g L−1 and the marketable water use efficiency was 5.3 g L−1. This suggests that 75% irrigation can be a viable alternative to full irrigation (100%) and offers water-saving potential, particularly in areas with limited water resources.