The Possible Use of Humic Acid Incorporated With Drip Irrigation System to Alleviate the Harmful Effects of Saline Water on Tomato Plants
Year: 2008
Type: article
Abstract: The main purpose of this work was to evaluate the possible use of humicacid mixed with the irrigation water through a drip irrigation system toalleviate the harmful effects of salinity stress on growth, fruit yield and qualityof tomato plants (Lycopersicon esculentum, c.v. 1077 hybrid). To achieve thistarget a field experiment was carried out on a private farms at Sedmant ElGabal village, Beni-Suef Governorate, Egypt, which represents one of thethose are occupying the desert zone adjacent to the western edge of the NileValley during two successive seasons of 2005-2006 and 2006-2007. Twoirrigation water resources were used, i.e., the Nile water (C1S1, ECiw = 0.56dS/m and SAR = 2.13) and a mixture of agricultural drainage saline water withthe Nile water at a ratio of about 1:1 (C2S1, ECiw = 1.89 dS/m and SAR =5.35). Humic acid was applied at rates of 75, 150 and 225 mg/L through a drip < br />irrigation system twice/week and for a period of 4 months after transplanting.The obtained data reveal that the studied soil is mainly encompassingthe wind blown sand deposits as a parent material, and it is classified asTypic Torripsamments, siliceous, hyperthermic and it could be evaluated asmarginally suitable. The results also show that usage of saline water resultedin relative increases of the ECe and ESP values in the root zone reached 18.95and 33.09 % as compared to the initial state of soil, respectively. Meanwhile,the corresponding relative increases of the ECe in case of amended salineirrigation water with humic acid at rates 0. 75, 150 and 225 mg/L were 11.75,5.09 and 2.98 %, vs 10.84, 3.76 and 1.73 % for the ESP values, respectively,with its optimal case at a rate of 225 mg/L. Moreover, the applied humic acidsplayed an important role in improving the values of soil bulk density, totalporosity, available water and hydraulic conductivity, organic matter content,pH, CEC and available nutrients. The latter may be due to modified airmoisture regime that leads to alleviate the depressive effect of salinity stresson the released nutrient from organic residues.These favourable conditions of the improved soil due to amendedirrigation water positively reflected on the vegetative growth and floweringparameters of tomato plants, i.e., plant height, number of leaves/plant,thickness of stem/plant at soil surface, number of branches/plant, leaf area,number of inflorescences/plant, number of flowers/inflorescence, dryweight/plant, and the chlorophyll a & b contents. It is evidently that suchbeneficial effect of humic acid on the dry matter productions was moreattributed to the leaves area and number, which are contributed to morephotosynthesis and better carbohydrates yield. Also, the ability of humic acidfor increasing plant nutrient uptake is due to its chelating property. Moreover,the applied humic acid at all the different rates resulted in significant increasesfor N, P and K in tomato leaves. The reverse was true for Na and Cl, probablydue to alleviate the harmful effect of saline irrigation water. In addition, usinghumic acid at the rates of 150 and 225 mg/L mixed with saline irrigation water registered almost similar tomato yields to those irrigated with the Nile waterand higher than those irrigated with either saline water or treated with at a rateof 75 mg/L humic acid. The relative increases in fruit yield/plant or fed couldbe attributed to significantly higher increments in dry weights and number offlowers/plant. The parameters of tomato fruit quality, i.e. average weight offruit, fruit firmness, total soluble solids (TSS), vitamin C (ascorbic acid),titrable acidity (citric acid) and total sugar showed significantly increasedwhen treated with amended saline irrigation water with humic acid at theapplied rates as compared to the effect of used saline water solely. Thus, thepresent study shows that the best rate of the applied humic acid mixed with theused irrigation saline water was 150-225 mg/L for achieving the greatesttomato yield of high quality.
Authors: Ashraf S. Osman, Mohamed S.A. Ewees
Institution: Fayoum University
Language: English
Subfield: Plant Science
Domain: Life Sciences
Open Access status: diamond
OpenAlex ID: W3210551794