Evaluation of Yield and Energy Budget of Muskmelon Grown in Horizontal Hydroponic System under Different Nutrient Input

The current research aimed at evaluating yield and energy budget of muskmelon grown in horizontal hydroponic system under different nutrient input conducted in a greenhouse in the new An-Najah National University campus. The hydroponic system consisted of four rectangular metal canals (28 cm wide, 22 cm high, 27m long) filed with non-growing media. Muskmelon seedlings were planted in the hydroponic canals and fertigated with different nutrients (Nitrogen, Potassium and Phosphorus - NPK-) and salinity levels. The extents of nutrient and salinity uptake and impact on plant growth , yield and energy budget were evaluated for one growing season. Experiment started in 26th of March, 2013 as follows: • Three canals were filled with a nutrient solution containing: Nitrogen, Phosphorous and Potassium with different amount of concentration for each canal ((1/4) copper, (1) copper and (1) copper +1000 ppm salts (NaCl)) respectively. • The fourth canal was used as a reference, so no additions were inserted. • Fresh water was allowed to enter the system from a tank that filled the champers in each canal. • Excessive water was discharged from the end of the canal to a drainage tank. After the completion of the experiment, nutrient solution was stored at −20 ◦C for nutrient analysis. Ion nitrate was determined by the Kjeldahl method. Macronutrients (P and K) were measured directly and simultaneously from nutrient solution using emission spectrometry. Results were expressed as mg dry weight plant−1 day.−1 Results for all nutrients used in the fertigation process indicated that: 1. Nitrogen percentage in stem and leaves had the largest percentage compared with roots and fruit, because nitrogen is concentrated in plant leaves. And it is observed that canal (2) had the largest value of nitrogen percentage compared with canals (1,3 and blank) . 2. Phosphorus concentrations in stem and leaves had the largest percentage compared with roots and fruit, because this element has a role in plant photosynthesis that concentrates phosphorus in plant leaves. It is observed that canal(2) had a large value of phosphorus in comparison with canals (1,3 and blank). 3. Potassium concentrations, roots had the large percent compared with (stem and leaves) and fruit, because these elements should be added to plant in the fruiting stage, for this reason adding more potassium before this stage or after it made potassium accumulate in roots .But it was observed that canal(2) had a large value for potassium compared with canals (1,3 and blank). Results of total sugar for canals 1 and blank were approximately equal and differ from canal (2 and 3) that had larger percent of total sugar in the plant. This was due to large amounts of fertilizer added to these two canals (2 and 3). Conductivity results indicated that stems and leaves had the largest conductivity value in the same canal while roots and fruits had the least value . But making a comparison between the four canals , canal 3 had the largest value, because (NaCl) salt was added to this canal. As an outcome of this research it was concluded that: 1. Plant growth increased when Adding more fertilizer like canals 2 and 3 compared with canal 1and blank . 2. Energy budget increased when more fertilizer added to the plant like canals 2 and 3. 3. The presence of salt (NaCl) in canal (3) prevents plant from absorbing water and all nutrients from canal which leads to a decrease in plant productivity.