The Effect of Different Levels of Irrigation and Plastic Mulch on Yield and Yield Components of Medicinal Pumpkin (Cucurbita pepo convar. pepo var. styriaca) in Mashhad

Medicinal Pumpkin (Cucurbit apepo convar. pepo var. styriaca) is a valuable medicinal plant in pharmaceutical industry. Iran has a semi-arid climate and located in areas suffer from water stress which can be considered as the biggest problem in crop production. Therefore, to achieve the highest yield of products in times of stress, the crop should be under full irrigation or proper management to make better use of the water in critical phases of crop growth. One of these managements is to reduce soil evaporation by using mulch .Mulching, reduces the amount of sunlight and preventing water evaporation effects on microclimate and provides a favorable environment for plant growth and development. The water resources in the country are limited and it needs to be efficiently used. Then an experiment was carried out aiming to investigate the effects of different levels of irrigation and plastic mulch on yield and yield components of medicinal pumpkins in weather conditions of Mashhad. This study was conducted in split plot design based on randomized complete blocks with three replications at the Agricultural Research Station, Ferdowsi University of Mashhad during growing season of 2014-2015.The main plots were irrigation including 50, 75 and 100% crop water requirement and two black plastic mulch surface (presence and absence of mulch) arranged as subplot. The distance between rows of 200 cm and distance between two plants was 30 cm. There were three rows of cultivars in each plot with a density of 34.3 plants.m-2. Based on soil test results and fertilizer requirements, 180 kg.ha-1 of urea and 100 kg kg.ha-1 of P2O5 were given to the land. The planting was carried out two weeks after irrigation and according to the air temperature. Irrigation of plots was done every seven days by polyethylene pipes and the volume of water entering the plots was measured. Yield and its components were measured at the end of growing season. The results showed that irrigation reduction resulted in a significant (p<0.01) change in all studied traits. For example, 50 percent reduction in irrigation reduced fruit yield by 68 percent compared to control. Reduction in fruit yield under water stress conditions can be related to a reduction in flower production in plant. Mulch had also significant effect (p<0.01) on total dry weight, leaf area index, fruit yield, seed yield, harvest index, and also on 1000-seed weight (p<0.05). Use of mulch increased fruit and seed yield and harvest index by 38.4%, 38.4% and 30.6% compared to the lack of mulch, respectively through reduced soil evaporation and increases available water of plant. Irrigation× mulch affected significantly (p<0.01) on total dry weight, leaf area index, harvest index fruit and seed yield, and seed weight per plant. Plant yield reduction under drought stress could be could be attributed to decrease in plant photosynthesis, leaves aging, and decrease in gas exchange due to stomatal closure. In general, irrigation of 75% of the plant's water requirement and the use of plastic mulch is the best condition for planting Medicinal Pumpkin. Because it greatly saves water consumption and also had the highest rate of production. The results of this study indicated that irrigation based on plant need can play an important role in increasing yield and yield components of pumpkin plant in drought conditions Also, the plastic mulch by preventing water loss, increases the amount of water available to the plant and reduces the effect of stress and improves plant yield.
Acknowledgement: This study has been funded by the University of Mashhad faculty of Agriculture and we would like to thank you in this regard.