استخدام التهوية الطبيعية لتبديد الحرارة و الرطوبة الزائدة داخل البيوت البلاستيكية و تأثيرها على إنتاجية محصول الخيار

This study was conducted in plastichouses belonging to Agriculture and Forestry College / University of Mosul in 2012 – 2013. The current research includes a design of tubes and ventilation vents in the plastic plastic house to dissipate heat a cumulated gets inside the plastic house naturally. This heat is calculated theoretically and practically. Moreover, exit the excessive moisture to the outsidewhich affects plant growth and increases disease spread especially fungal infections. Five Plastic houses were planted with cucumber crop and the first one has been selected to be reference which is without ventilation, while the other four houses were supplied by vents and ventilation tubes for as follows: Vents and tubes of 0.4m diameter and 2.5m distance, 0.4m diameter and 5m distance, 0.6m diameter and 2.5m distance, of 0.6m diameter and 5 m distance. Data were taken for the studied properties from temperature and relative humidity, as well as vegetative and fruit crop recipes. Also severity of pathological casualty were accounted. The forth treatment which is in 60cm tube diameter and 2.5m distance recorded highest heat dissipate in terms of the rate of mass transfer (ṁr) 5.31 kg/s, number of air changing in the plastic house (N) 26 /hour, amount of heat disputed (Q-) 4442 kJ/day, less pathological casualty 0.24 and highest chlorophyll rate 41.56. While the best average productivity recorded for crop weight 303.80 kg/190 m² and number of fruits 4111 was in the fifth treatment which, 60cm tube diameter and 5m distance. This treatment where provided an convent environment for planted crop and gave the highest crop productivity with lowest construction cost as compared to the other treatments. The data were analyzed statistically for crop properties by using randomized complete block design in a split experience, where harvested yield sited ​​in the main plots and ventilation treatments sited in sub split plot.