Growth analysis of pumpkin (Cucurbita pepo convar. Pepo var. Styriaca) using measured parameters under various irrigation and plastic mulch treatments

In most developed nations, pumpkin-naked seed (Cucurbita pepo convar. Pepo var. Styriaca) is regarded as one of the most important and valuable plants in the pharmaceutical industry. In traditional and modern medicine, pumpkin-naked seed oil is used to treat a variety of diseases, including prostate hypotrophy, prevention of irregular heart contractions, and treatment of intestinal worms, as well as gastritis, atherosclerosis, decreased blood cholesterol, and decreased risk of bladder and kidney stones. Due to the fact that the environmental conditions for the growth of this plant are rarely optimal and the plants are subjected to a variety of stresses due to the influence of living and nonliving factors, plant yield is diminished relative to plant growth potential. The most significant non-living stress on plant growth and yield is typically drought, especially in arid and semiarid regions of the world such as Iran. About half of the world's agricultural lands are affected by drought stress. Drought stress has caused significant damage to the agricultural sector. Due to the importance of irrigation water in agriculture and the impact of drought stress on crop growth and yield, methods should be implemented to prevent water loss and improve the management of water resources in agriculture, which mitigates the effects of drought stress to some extent. Among these techniques is the use of plastic mulch. The use of plastic mulch in the cultivation of agricultural products for the purpose of increasing soil moisture by reducing the amount of sunlight reaching the soil surface and preventing water evaporation, reducing weeds in the field, and minimizing the damage caused by certain pests. Some crop yields have increased in agriculture throughout the world. This experiment was conducted to determine the effect of different irrigation levels and the use of plastic mulch on pumpkin-naked seed yield and yield components, growth indices, light consumption efficiency, and oil content as the most important quality traits. This study was conducted at the Agricultural Research Station, Ferdowsi University of Mashhad, during 2015-2016 growing season using a split plot design based on randomized complete blocks with three replications. The treatments consisted of three irrigation levels (50, 75, and 100 percent water demand) as the main plot and two mulch surfaces (presence and absence of mulch) as the subplot. At the end of the growing season, yield and its components were evaluated.  The use of plastic mulch for non-stress irrigation (irrigation 100percent water requirement) increased the number of seeds per plant by 5.7% and the relative water content of leaves by 12.8%, but had no significant effect on other traits. However, under mild stress conditions (irrigation of 75% of water requirement), all studied traits except relative growth rate increased, with grain yield (97.3%) having the greatest effect. Also, under conditions of severe stress (irrigation of 50% of water requirement), the use of plastic mulch had the greatest effect on grain yield (312%) but no effect on crop growth rate or relative crop growth rate. In general, the results indicated that maintaining soil moisture and irrigation based on the plant's water requirements can play a significant role in enhancing pumpkin growth and yield. In addition, it was observed that irrigation at 75% of the plant's water requirement and the use of plastic mulch produced the greatest yield, light consumption efficiency, growth indices, and oil content. Therefore, the use of plastic mulch is an effective method for reducing the amount of water a plant consumes in conditions of dehydration.