Journal of Plant Pathology & Microbiology

Abstract

Substrate Effects on Plant Transpiration Rate under Several Vapour Pressure Deficit (VPD) Levels

Md Rais Uddin Rashed

Vapour pressure deficit (VPD) is considered as an important environmental factor that affects transpiration rate (TR) in plants. VPD is the difference between the amount of moisture in the air and the amount of moisture the air can hold when saturated. Since VPD increases, the drying ability of air increases. Plants transpire more, requiring more water to be drawn from the roots. As the guinea grass are well adapted in various types of soils, therefore in this study, Panicum (Panicum maximum cv. tanzania) was used with 4 different substrates (hydroponic, organic, sand and mineral) subjected to low (0.50-1.50) and high VPD (2.50-3.90) environments to study their substrate effects on plant transpiration rate in 3 different growth stages (31, 37 and 43 DAS for organic, sand and mineral soil and 25, 31, 38 DAS for hydroponic respectively). The highest transpiration rate of Panicum was measured in hydroponic condition (5.44) under higher VPD level and lower leaf area. The lowest TR measured in sandy soil (0.17) with lower VPD level and large leaf area.

The results showed that sand substrate has the lowest transpiration rate and hydroponic condition showed highest transpiration rate. Other substrates rate in between two of them. However, the results showed that overall transpiration rate was significantly decreasing along the growth stages. Adding more substrates and tying a small around all the exposed leaves would be the way to obtain the exact amount of water transpired from the water source, which makes the results more comparable among the substrates.