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Abstract
A field experiment was carried out to elucidate the possibility of using chloride form as a partial source for potassium in fertigation of banana plants grown on a sandy soil. Growth, fruit yield and quality as well as plant nutritional status and Cl accumulation within both plant leaves and rhizosphere beside an economical elucidation were taken into consideration to accomplish such evaluation. Eleven gradual increasing KCl: KNO3 (0:100 - 100:0) ratios were applied with maintaining the concentration of all macro and micro nutrients except Cl constant.
Obtained data indicated that increasing Cl existence didn’t adversely affect plant growth under this experiment. Treatments of 10:90 followed by 50:50 as well as 70:30 followed by 80:20 and either 90:10 or 10:90 (KCl:KNO3) were most stimulating treatments for increasing pseudo stem diameter and leaves number, respectively. Although total fruit yield bunch as well as number and length of fingers are less sensitive to increasing KCl: KNO3 ratio, number of hands/bunch and diameters of fingers were significantly and positively affected by increasing KCl existence.
Treatment of 80:20 KCl: KNO3 was the most significant superior one for all measured fruit yield parameters. Although Cl content increased significantly in banana leaves and root surrounding area with increasing Cl existence in the fertigation solutions, recorded contents seemed to be in safe ranges whereas no chloride necroses symptoms were appeared at banana leaves.
Contents of N, P and K as well as Cl in plant leaves were significantly, although in fluctuating manner, affected by increasing chloride occurrence in fertigation solution. The encountered response of N, P and K contents seemed to be not only a resultant of increasing Cl occurrence in the root media but also as a reflection to changing the N form (NH4 and urea) compensating N-NO3 decline in the fertigation solutions having high Cl concentrations. The relatively high supplements of Cl (80:20 followed by 70:30 KCl: KNO3) recorded the highest economical net return. It could be concluded that KCl can be perfectly used in fertigating banana plants grown on sandy soils. To increase safety of using chloride under such conditions, more work could be suggested particularly what concerns with calculating irrigation and leaching water requirements to prevent chloride accumulation in the root zone.
From the above mentioned results, it could be noted that banana plants showed a positive response to fertigation with different combinations of K-KCl: K-KNO3. From both economical and biological point of view, therefore, it could be concluded that fertigation with low-price and high water soluble KCl as a main source of potassium requirements is recommended for banana plants grown on a sandy soil and irrigated with water low in salinity and chloride content without any adverse effect on banana crop yield and quality.