Agaricus bisporus Compost, Foliar Potassium, and Boron Applications for Enhanced Flowering and Yield of Cucurbita pepo L. Under Field Conditions

A field study was conducted at the Agricultural Research Station of the College of Agriculture, University of Kufa, for the agricultural season 2022?2023 to evaluate the effect of a biofertilizer prepared using wheat straw?Agaricus bisporus mushroom compost and foliar spray with potassium or boron. Their interactions on flower growth and yield of the squash plant, Cucurbita pepo L. (Squash Ahmed F1 hybrid), were determined. The experiment was factorial (3 ? 4) as a randomized complete block design with two factors and three replicates. The first factor was planting soil treatment with straw composted by A. bisporus at three levels of 0, 1, and 2 g/plant at four true leaves stage. The second factor was spraying with 2 mL/L of potassium or boron or a combined treatment of both. The results showed that the bio-fertilization treatment with straw-mushroom compost was superior in increasing the number of pistillate flowers, reaching 15.26 flowers/plant, the average sexual ratio of 0.67%, and the fruit set of 65.86%, compared to the control treatment where 13.76 flowers/plant, 0.60% sexual ratio, and fruit set of 58.98%, respectively, was recorded. The foliar spray with boron at 2 mg/L was significantly effective in increasing the same parameters by 15.27 flowers/plant, 0.69%, and 64.67%, respectively, compared to the control..