Effect of Irrigation Water on Growth and Physical Characteristics of Alfalfa (Medicago Sativa) and Mung Bean (Vigna Radiata) Sprouts

With resources to produce food predicted to become scarce and strongly limited,the need for producing more and consuming fewer resources will become increasingly important in the agricultural environment. Production methods that are ‘soil-less’ which are not tradition in-ground methods are viewed as creative solutions that have the potential of being sustainable. An aquaponic system is one of these productions methods that have the potential to be sustainable. Research demonstrates the water conservation an aquaponic system can establish if proper management is maintained, thus upkeep and monitoring of water quality parameters are crucial for successful growth of plants. The purpose of this study was to evaluate the production characteristics of alfalfa and mung bean sprouts grown in different water sources (Aquaponic and municipal tap water). Seed length and width, root length and width, stem length and width, leaf length and width, number of leaves, branched roots, and whole length were evaluated on alfalfa and mung bean sprouts that were grown in either municipal tap water or aquaponics water. Day 7, the sprouts from all treatments were harvested and color analyses were conducted. Two separate conditions a greenhouse setting and a laboratory setting for the production of sprouts was observed for the study. Water quality parameters were also observed in the systems including: pH, chemical oxygen demand (COD), oxidation-reduction potential (ORP), nitrogen levels, phosphorous levels, total solids, total suspended solids, absorbance levels, dissolved oxygen, and electrical conductivity. Data demonstrated that alfalfa sprouts grown in the laboratory environment had no difference between the harvest whole lengths of alfalfa sprouts. However, the stems on the alfalfa sprouts in the controlled laboratory environment were longer than the alfalfa sprout stems grown in the greenhouse environment. In the laboratory setting, alfalfa seeds irrigated with municipal tap water were approximately 26% longer than the seeds irrigated with aquaponic water. The aquaponically grown mung bean sprouts whole length was longer in the greenhouse environment compared to the mung bean sproutsgrown in the laboratory setting. The mung bean sprouts irrigated with aquaponic water in the laboratory setting was shorter in length (aquaponic length 100 mm versus tap length 137 mm) (P-value 0.0002). The opposite of what was observed in the greenhouse experiment. The aquaponically grown alfalfa sprout had a higher L* value indicating that the alfalfa sprouts grown in the aquaponic water had a darker color leaf compared to the municipal tap water alfalfa sprout. The aquaponically grown mung bean also had a higherL* value which indicates that the leaves have a darker tone. Weekly monitoring of the aquaponic system was also evaluated throughout the study. There was a difference between the municipal tap water and aquaponic system in water chemistry and color analysis. The aquaponic system had higher nitrogen and phosphorous levels along with higher total solids and total suspended solids. Results from these studies demonstrate that the aquaponic system was sufficient to produce both alfalfa and mung bean sprouts and although the aquaponic system resulted in improved production characteristics such as taller sprouts with longer root systems than the tap municipal systems, a higher yield was not observed in the aquaponic system that has been seen with other aquaponically produced crops