Estimation of Water Losses by Transpiration from Root and Leaf Clipped <i>Eichhornia Crassipes</i> (Water Hyacinth)

Abstract

Among several alien weeds Eichhornia Crassipes (water hyacinth) is ranked as one of the world’s worst invasive weeds due to its ability to rapidly cover  the entire water surface. This weed was introduced in Ethiopia in 1964 but its aggressiveness has been realized recently after it has invaded a number of  lakes and rivers in the country. This study focuses on the estimation of water losses by transpiration from root-clipped, leaf-clipped plants (treatments)  and makes comparison with those of the normal plants (control). Besides evaporative losses, crop factors and plant coefficients were also determined  and compared. Plant transpiration losses were obtained from the difference in the volume of water from the pan containing the treatment and control  plants and the volume of water lost from the pan evaporation. For this calibration first was done to correlate the depth of water level (in the pan) from  the top of the pan to the water level in order to know the volume of water lost by evapotranspiration. Data analysis was made using Microsoft Office Excel  and comparisons were made using one-way ANOVA followed by pair comparisons. Evapotranspiration estimation for Zeway area was done using  the modified and optimized Temesgen-Melesse’s method, and the study was conducted for 17 days. The result showed that the evapotranspiration by  normal plants (control group), plants with clipped roots (CR), and plants with clipped leaves (CL) were 2.25L/d (7.96 mm/d), 0.85L/d (3.01 mm/d), and 1.51  L/d (5.34 mm/d), respectively, compared to mean daily pan evaporation of 0.88 L/d (3.11 mm/d). The transpiration rates from the normal and leaf-clipped  plants were 1.37L/d (4.85 mm/d) and 0.72 L/d (2.55mm/d), respectively. The root-clipped plants did not show any transpiration at all. Additionally, the  value of crop factors (Cp) calculated showed 1.09, 0.40 and 0.73 for C, RC and LC, respectively. The crop coefficient (Kc) result showed 1.42, 0.54, and 0.95 for C, RC and LC, respectively. ANOVA results of T, Cp showed significant differences between treatments and the control and also within treatments. The  conclusion drawn is that root-clipping has better effect than clipping of leaves when it comes to reducing the rate of transpiration from the plant. It is  better to find other physical methods of ill-managing the plant rather than trying to remove the entire plant from water bodies since it is too  cumbersome.