Effects of Salinity, Nutrients, Heavy Metals and Organic Matters on Growth, Yield and Uptake of Pea in Piped Hydroponics

Population growth in Palestine and consequent increased water consumption lead to erosion of arable land and reduction in fresh water suitable for agriculture, so hydroponics may be the most appropriate alternative in these circumstances. The main objective of this research is to study the effect of three salinity levels(750, 1500 and 3750 ppm NaCl) , two levels of micro and macronutrients(Cooper, 1/4 Cooper solution) and of heavy metals(3.26 , 3.2 , and 2 ppm Zn, Cu and Fe, respectively ) on growth, yield, and uptake of pea plants grown in piped hydroponic. Six inches plastic (PVC) pipe have been used in closed hydroponics, that contain sites growth, injection tubes, sprayers, drainage tube, as well as 120 liter drums and pumps (1/2 Horse Power). The experiment was divided to six lines that depended on composition of nutrient solutions as mentioned above, each line included five pipes, each pipe contains a four seedlings, and all the pipes in various lines have been raised on a wooden stand about one meter. Then seeds are planted in organic soil for approximately 15 days, placed in a pot or a bin and installed by substrates and transferred to the pipelines of growth chambers that received tap water for one week and replaced with nutrient solutions that are previously prepared and pumps run three times for entirety 1.5 to 2 hours a day. Experience has shown survival percentage of six lines: 100%, 95%, 90%, 80%, 50% and 70%, respectively. The plants separated and divided into pods, leaves, stems and roots, then physical and chemical measurements conducted on them. It has been observed that the different salt proportion and nutrients and heavy metals affect significantly the quantities of some nutritional elements, and a negative effect on morphological characteristics of plants at high salinity of nutrient solution, that's where the plants under 3750 ppm did not produce pods. The best growth and yield and weight plants were in the Line 1, where fresh weight of pods, leaves, stems and roots were measured (6.53, 1.81, 1.58, 1.60 g), respectively . The least growth, yield and biomass plants were in the Line 5. Fresh biomass weight of pods, leaves, stems and roots (0.00, 0.23, 0.21 and 0.15g/plant), respectively. Stems and roots of plants that grew in Line 6, they had length 20.21, 21.07 cm that more than control . the performance of the plants have dropped under nutrient solution which has deficiency and decreased relative water content with increasing salinity (Ec) between 79.10% and 86.00%, where the relative water content relied directly on the salinity of the solutions, with the exception of the Line 6 was less than expected. Increasing the concentration of sodium chloride in the nutrient solutions that led generally to increase the concentration of sodium and chloride ions in plant parts, and particularly to increase chloride concentration in the roots( largest value 5.16% in Line 5 ) and sodium in the leaves and stems (largest values 4.90% and 6.11% in Line 5). Concentrations of nitrate and potassium in plants has decreased due to the impact and interact with chloride and sodium ions ,respectively. Calcium percentage found in Line 2 is greater than Line 1, but in roots decreased (3.76% , 2.63% respectively), in roots of Line 6 more than Line3 (1.74% , 1.57% respectively), the greatest phosphate percentage in whole plants of Line 1 ( 0.64%). In general, high salinity led to decrease the elements in plant parts, but some elements increased in plant parts such as phosphorus in the roots, and other elements has increased in the leaves or stems, such as magnesium and calcium and phosphate in the pods peas, but nitrate was noted a slight increase in leaves of plants at 1500 ppm NaCl (Line 4) became (0.71%). The largest weight copper and zinc were found at the root of Line 6 (36.05 and 211.58 mg/kg dry plant, respectively). The effect of nutrients on plant peas have been positive, but increased nutrient value that needs the plant does not lead to growth, yield and production more than usual and decreased with increasing salinity, However there are complex interactions between the ions within the plants. The recommendations to the Palestinian community, it is desirable to use PHS because it does not need a large space and fertilizers as well as use water has electrical conductivity about 4 ms/cm, in addition it economically feasible, and recommendations fot researchers; study the effect of salinity on pea plants in hydroponics at different levels of salinity between the extent (1500 - 3750) ppm NaCl, in order to determine the maximum tolerable in peas without affecting the growth and performance of the plant and study the effect of a few types (pairs) of nutrients within different levels of salinity, due to the existence of relationships and complex interactions occur between the ions in nutrient solutions and within the plant tissue.