Selection of optimal design of polyhouse and suitable variet-IES of salad cucumber under humid tropical climate

In order to select most suitable design of polyhouse under humid tropical climate of Kerala for cultivation of salad cucumber, three naturally ventilated polyhouses having different shapes (namely gable, quonset and mansard shapes) with the same floor area (150 m²), same eave and ridge height and same roof and side ventilation were designed and constructed at HTR&TU, KAU, Vellanikkara, Thrissur; FSRS, Sadananthapuyram and RARS, Ambalawayal. Study was conducted by observing the temperature and relative humidity inside the polyhouses. The temperature inside Gable shaped polyhouse was found to be lesser than Quonset and Mansard shaped polyhouses. During peak hours of the day (12 pm to 2.30 pm), temperature inside gable shaped greenhouse was 1.5 to 2°C lesser than other two greenhouses. Relative humidity inside gable shaped polyhouse was found to be lesser during night time and more in peak hours of the day. Among thesix varieties of salad cucumbertested in each polyhouses, Rica gave maximum yield in all the structures. But there was no significant difference between the yield of KUK9, 52-55and Rica in all the polyhouses. But the yield of Multistar, Kafka and Y225 was significantly lesser than above said varieties. It was found that compared to other varieties, KUK9 is more resistant to Downey mildew. Study revealed that all varieties gave better yield in Gable shaped polyhouse compared to Quonset and Mansard shaped polyhouses. The analysis of climatic parameters and yield & growth characteristics of salad cucumber revealed that optimalpoyhouse design suitable for Kerala homesteads in plane area is gable shaped structure oriented in north-south directionand that at hilly area, both Gable and Quonset shape structures can be adopted.