EFFECT OF SALINE WASTE WATER IRRIGATION ON GROWTH, SURVIVAL AND PHYSIOLOGICAL RESPONSE OF ORNAMENTAL FOLIAGE PLANTS
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Date
2016-10-24
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College of Horticulture, Rajendranagar, HYD-30
Abstract
The present investigation entitled “Effect of saline wastewater irrigation on growth, survival and physiological response of ornamental foliage plants” was carried out at College of Horticulture, Rajendranagar, Hyderabad during the year 2015-16. The twelve foliage species viz., Aralia, Schefflera, Leucophyllum, Dracaena, Cordyline, Coleus, Graptophyllum, Croton, Philodendron, Pleomele, Red bog lily and Chlorophytum were selected for screening of salinity in wastewater. Each of the foliage plant species was imposed with four irrigation treatments consisting of a) tube well water (control-T1), b) 100% wastewater (T2), c) Blending tube well and wastewater in 50:50 ratio (T3) d) Leaching with tube well water after two wastewater irrigation events (T4). The wastewater was collected from seepage of Kattedan industrial area. The experiment was laid out in Factorial CRD in pot culture replicated thrice. The observations were recorded on the plant growth, survival, visual quality and physiological responses to wastewater irrigation. Further the nutrient content of leaves in different treatments and salt build up in soil was analyzed at the end of the experiment.
The preliminary analysis of water samples in each of the treatments revealed that wastewater contained higher levels of EC, pH, TDS, Cl, SAR, RSC when compared to tube well water (control) and was categorized as saline wastewater. The wastewater also contained higher amounts of nutrients like N, P, K and micronutrients. The analysis of soil leachate collected from plants flushed with tube well water after two wastewater irrigations (T4) revealed higher levels of EC and pH than tube well water (control). Significant variation in the growth parameters was observed among the foliage plant species in different irrigation treatments. There was a reduction in plant height in all the foliage plant species when irrigated with wastewater (T2) when compared to plants irrigated with tube well water (control-T1). Contrary to this, there was an increase in growth parameters like number of leaves, fresh weight of shoots, and dry weight of shoots in Croton, Pleomele and Philodendron when irrigated with 100% wastewater. While fresh and dry weight of roots had increased in Red bog lily, Croton and Philodendron species. Further leaf area increased in Leucophyllum, Philodendron, Pleomele, Red bog lily and Chlorophytum, when irrigated with wastewater (T2).
The observations on visual quality parameters were recorded at fortnightly intervals. The toxic symptoms appeared on foliage of Coleus, Gratophyllum, Cordyline and Red bog lily after 50 days of imposing wastewater treatments. They appeared as yellowing of leaves, chlorosis, necrosis, clearing of pigmentation, cupping of leaves, tip burn and reduction of leaf size. Further slight to severe defoliation was also observed in Coleus, Graptophyllum, Leucophyllum and Red bog lily. While there was 100% mortality of Graptophyllum plants under 100% wastewater irrigation at 120 days after imposing treatments. Among the physiological parameters, the total chlorophyll content in foliage plants species such as Schefflera, Cordyline, Coleus, Graptophyllum and Philodendron increased in wastewater irrigation when compared to control while Relative Water Content (RWC) decreased in all foliage species irrigated with 100% wastewater.
The leaf analysis of twelve foliage species revealed an increase in nutrient (N, P) and salt composition (Ca, Na and Cl) under 100% wastewater irrigation (T2). All the foliage species except for Leucophyllum, Coleus, Graptophyllum, Cordyline and Red bog lily showed maximum K and K/Na ratio under wastewater irrigation while maximum Mg content was recorded in all the foliage species except for Aralia, under irrigation with blended water (T3). The soil under different wastewater treatments were analysed at the end of the experiment and the results revealed that the EC and pH was highest in wastewater irrigated soil when compared to tube well water (control-T1). Further, the soil analysis also revealed that nutrient and salt content of soils irrigated with wastewater had increased when compared to control.
Based on the growth, survival, visual quality parameters and physiological responses of the foliage species, Aralia, Schefflera, Dracaena, Croton, Philodendron, Pleomele and Chlorophytum were found to be highly tolerant to salinity hence performed best under wastewater treatments. The relative tolerance of these species to saline wastewater was judged based on their ability to survive under high EC along with high accumulation of root and shoot biomass, ion content and K/Na ratio. The foliage plant species viz., Graptophyllum, Coleus, Leucophyllum, Cordyline and Red bog lily were found to be highly sensitive to salinity under wastewater irrigation where visual quality was reduced. The nutrient composition and salt buildup in both leaf tissue and soil increased when irrigated with wastewater however it was in safer limits for irrigating salt tolerant species. The beneficial impact of flushing with tubewell water after two wastewater irrigation events in containerized plants removed excess salts and was found to be congineal for growing foliage plants. Blending of both tube well water and wastewater reduced water EC hence emerged as a viable option for irrigating sensitive foliage plant species.
The present study has established that wastewater can be a viable option for irrigating containerized foliage plants with proper leaching without affecting the plant or soil health. Thus with the adoption of suitable salt tolerant species, wastewater provides an additional and viable irrigation source where the supply of fresh water is limited.
Description
The preliminary analysis of water samples in each of the treatments revealed that wastewater contained higher levels of EC, pH, TDS, Cl, SAR, RSC when compared to tube well water (control) and was categorized as saline wastewater. The wastewater also contained higher amounts of nutrients like N, P, K and micronutrients. The analysis of soil leachate collected from plants flushed with tube well water after two wastewater irrigations (T4) revealed higher levels of EC and pH than tube well water (control). Significant variation in the growth parameters was observed among the foliage plant species in different irrigation treatments. There was a reduction in plant height in all the foliage plant species when irrigated with wastewater (T2) when compared to plants irrigated with tube well water (control-T1). Contrary to this, there was an increase in growth parameters like number of leaves, fresh weight of shoots, and dry weight of shoots in Croton, Pleomele and Philodendron when irrigated with 100% wastewater. While fresh and dry weight of roots had increased in Red bog lily, Croton and Philodendron species. Further leaf area increased in Leucophyllum, Philodendron, Pleomele, Red bog lily and Chlorophytum, when irrigated with wastewater (T2).
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Citation
Sri Konda Laxman Telangana State Horticultural University, Rajendranagar, Hyderabad-30