Growing Media Including Palm Waste in Soilless Culture of Cucumber

International Journal of Vegetable Science, 18:1 9, 2012 Copyright Taylor & Francis Group, LLC ISSN: 1931-5260 print / 1931-5279 online DOI: 10.1080/19315260.2011.568599 Growing Media Including Palm Waste in Soilless Culture of Cucumber F. Pooyeh, 1 Gh. Peyvast, 2 and J. A. Olfati 2 1 University of Azad, Jiroft Branch, Jiroft, Islamic Republic of Iran 5 2 University of Guilan, Horticultural Department, Rasht, Islamic Republic of Iran Cucumber (Cucumis sativus L.) is a vegetable crop that can be produced in greenhouses. The occurrence of soil-limited factors has increased interest in soilless culture and the demand for a suitable technology adapted to this type of production. Palm waste is readily available and cheap, and this study was conducted to investigate the effect of 10 substrates, including some with palm waste, on growth, yield, and quality of cucumber. An equal mix of perlite and palm waste produced results that were similar to the best results for most traits. This material can likely be used as a part of a suitable media for cucumber production in soilless culture. Keywords Cucumis sativus, Iran,, Perlite, Quality, Yield. 15 Cucumber (Cucumis sativus L.) is a vegetable crop that can be produced in greenhouses. Expensive chemical soil disinfection methods, low yields, and possible plant residues have increased interest in soilless culture and the demand for a suitable technology adapted to this type of production (De Rijck and Schrevens, 1998). Soilless cultivation is intensively used in protected 20 agriculture, especially for crops during months when field production is not possible, to control the growing environment and avoid uncertainties in water and nutrient status of the soil. Soilless cultivation has the capacity to increase yield and replace major amounts of field production as well as improve efficiency and product quality (Verdonck et al., 1983). Humic substances from 25 bark sawdust can be used as a growing medium (Nakano, 1994). It is common practice to mix vermiculite, perlite, pumice, or sand with organic substrates to provide increased porosity and water-holding capacity (Hardgrave and Harriman, 1995). Address correspondence to J. A. Olfati Horticultural Department, University of Guilan, Rasht, Islamic Republic of Iran. E-mail: jamalaliolfati@gmail.com Q2

2 F. Pooyeh et al. Soilless cultures using peat have been used (Andreas, 1992; Benoit and 30 Ceustermans, 1987; Goehler, 1994; Schroeder, 1992; Vogel, 1994), but there are concerns about the harmful effects of peat extraction on the environment. These concerns have initiated a search for materials that are readily available, affordable, suitable for use as growing media (Ortega et al., 1996), and have specific physicochemical properties. Many organic wastes, or by-products after 35 composting, have been found to be suitable for use as organic substrates in soilless culture (Benito et al., 2006; Cáceres et al., 2006; Yu and Komad, 1999; Zaller, 2007; Zhang and He, 2006). In tropical environments palm waste is readily available and low cost. This study was conducted to investigate the effects of growing media, including mixes with palm waste, on growth, yield, 40 and quality of cucumber. MATERIALS AND METHODS The cucumber cvs. Royal, Negin, and Zohal were used for experiments conducted in a glass greenhouse in 2010. The substrates, peat, perlite (2 3 mm), palm waste ( 1 cm), palm waste + peat (50:50 v/v), perlite + peat (50:50 v/v), 45 and palm waste + perlite (50:50 v/v), were arranged in a completely randomized experimental design with three replications. Cucumber seeds were sown on 2 Mar. 2010 in single plastic pots (12 11 cm) filled with peat. Transplantation was on 23 Mar. 2010 into 24-L bags at a plant density of 3.1 plants per m 2. Plants were grown vertically, 50 allowing the principal stem to grow. Nutrient solutions (Tables 1 and 2) were prepared with municipal tap water and delivered to plants by a drip irrigation system (Olfati et al., 2008) with pressure compensated by 2 L h 1 drippers, two per plant. Temperature inside the greenhouse was maintained between 27 and 18 C (day and night). Side shoots were pruned to two fruit and/or two 55 leaves (Peyvast and Charavi, 2005). Harvesting was from 21 Apr. to 30 May 2010 (26 times). Each experimental unit contained 10 plants and 3 plants per experimental unit were sampled. Plant length, number of nodes per plant, internode length, number of leaves, fruit number per plant, fruit weight, length and volume, fruit dry 60 matter, percentage ash, total soluble solids, total acidity, total carotenoid, total phenol, vitamin C, and antioxidant capacity were determined. Table 1: Macronutrients used in nutrient solutions. meq L 1 KNO 3 K 2 HPO 4 KH 2 PO 4 NaCl CaNO 3 MgSO 4 NH 4 NO 3 NO 3 PO 4 nutrients Total all 3.2 2.4 0.9 0.2 5.2 1.5 0.1 8.5 3.3 13.5

Growing Media in Soilless Culture of Cucumber 3 Table 2: Micronutrients used for nutrient solution preparation. Compound Irrigation solution (mg L 1 ) (NH 4 ) 6Mo 7O 2 /4H 2 O 0.1 H 3 BO 3 1.5 MnSO 4 4H 2 O 2 CuSO 4 5H 2 O 0.25 ZnSO 4 7H 2 O 1 Sequesteren Fe 136 10 Table 3: Characteristics of substrates. Q1 Substrate ph Electrical conductivity (ds m 1 ) WHC (ml m 3 ) Perlite 7.36 0.22 500 5.97 0.82 775 Palm waste 6.91 1.11 620 + palm waste 6.65 1.01 800 6.86 0.78 680 Palm waste + perlite 6.86 0.62 730 Q5 Moisture, Total Soluble Solids, ph, and Titratable Acidity Moisture was determined by drying at 75 ± 5 C until samples reached constant weight (Association of Official Analytical Chemists [AOAC], 1984). 65 Total soluble solid contents (TSS) were determined by squeezing the tissue and placing one drop of juice from each fruit into a refractometer (HSR-500, Atago, Tokyo, Japan). The ph measurements were performed using a digital ph meter (WTW GmbH, Weilheim, Germany) calibrated with ph 4 and seven buffers. Titratable acidity (TA) was measured by the titrimetric method (AOAC, 70 1984). Determination of Ascorbic Acid Ascorbic acid was determined according to the 2,6-dichlorophenolindophenol dye method (Ranganna, 1997). Fresh fruit samples (10 g) were extracted by grinding in a mortar and pestle and 3% metaphosphoric 75 acid (v/v) was used as a protective agent. The extract was made up to a volume of 100 ml and centrifuged at 3000 g for 15 min at room temperature. Ten milliliters was titrated against 2,6-dichlorophenolindophenol dye that had been standardized against standard ascorbic acid. Results were expressed as milligrams per 100 grams on a fresh weight (FW) basis. 80

4 F. Pooyeh et al. Determination of Total Carotenoids Total carotenoids mg/100 g were determined by a modified method of Ranganna (1997) using acetone and petroleum ether as extracting solvents and measuring absorbance at 450 nm. Determination of Total Phenolics Compound 85 Methanol extracts of cucumber fruit (1 g cucumber in 10 cc methanol) were used for determination of total phenolics. Total phenolic content was evaluated by colorimetric analyses using Folin-Ciocalteu s phenol reagent (Singleton and Rossi, 1965). The total phenolics content was expressed as mg gallic acid equivalent/100 g of fruit. 90 2-Diphenyl-2-picrylhydrazyl Free Radical Scavenging Activity The free radical scavenging activity against 2-diphenyl-2-picrylhydrazyl (DPPH) was evaluated using the methods of Leonge and Shui (2002) and Miliauskas et al. (2004) with minor modification. In the presence of an antioxidant, the purple color intensity of DPPH solution decays and the 95 absorbance change is followed spectrophotometrically at 517 nm. The scavenging activity was expressed as IC 50 (mg ml 1 ). Data were subjected to analysis of variance in SAS (SAS, Inc., Cary, N.C.). If interactions were significant they were used to explain the data. If interactions were not significant, means were separated with Duncan s multiple 100 range test. RESULTS AND DISCUSSION ANOVA determined that cultivar and growth medium had little effect on most traits and the interaction was not significant for most traits (Table 4 8). diameter averaged 2.48 cm, fruit number averaged 56.17, fruit weight 105 averaged 4141.67 g, number of nodes averaged 52.6, number of leaves averaged 96.26, leaf dry matter averaged 16.89, plant length averaged 385.15 cm, internode length averaged 7.34 cm, fruit dry matter averaged 5.35%, fruit ash averaged 90.57%, TSS averaged 3.73 Brix, TA averaged 0.89%, carotenoids averaged 0.082 mg/100 g, antioxidants averaged 9.01 mg ml 1, vitamin C 110 averaged 10.03 mg/100 g FM, total chlorophyll averaged 0.18 mg ml 1, and total phenol averaged 0.08 mg/100 g. Variety affected some characteristics (Table 9). length and ph were highest for cv. Zohal. volume and root dry matter were highest for cvs. Royal and Negin. Internode length was higher in cv. Zohal than in cv. Negin 115 and cv. Royal was intermediate. Leaf DM was higher in cv. Negin than in cv. Zohal and cv. Royal was intermediate. Q3 Q4

Growing Media in Soilless Culture of Cucumber 5 Table 4: ANOVA table effects of treatments on vegetative plant development. Source df Plant length (cm) Number of nodes Internode length (cm) Number of leaves Variety (V) 2 8.00 NS 0.82 NS 5.14 2.71 NS Substrate (S) 5 17.64 NS 0.23 NS 1.01 NS 2.46 NS V S 10 3.99 NS 0.72 NS 0.99 NS 4.33 NS Error 36 5.47 0.65 0.74 0.65 Coefficient of variation (%) 12.01 11.18 11.71 11.18 NS, Nonsignificant and significant at P 0.01, respectively. Table 5: ANOVA table effects of treatments on root and leaf dry masses. Source df Root DM (%) Leaf DM (%) Variety (V) 2 22.48 55.49 Substrate (S) 5 17.46 5.12 NS V S 10 3.27 5.22 NS Error 36 1.12 6.25 Coefficient of variation (%) 11.04 14.8 NS, Nonsignificant and significant at P 0.01, respectively. Table 6: ANOVA table effects of treatments on reproductive development. Source df number per plant weight per plant (g) weight (g) volume (cm 3 ) diameter (cm) DM (%) Variety (V) 2 1.58 NS 9.36 NS 0.37 NS 3.07 0.007 NS 0.33 NS Substrate (S) 5 12.03 28.5 NS 0.66 0.85 NS 0.011 NS 0.22 NS V S 10 2.53 15.94 NS 0.12 NS 1.35 NS 0.003 NS 0.26 NS Error 36 1.16 10.57 0.17 0.73 0.005 0.38 Coefficient of variation (%) 14.61 12.21 5.53 11.23 2.92 11.54 NS,, Nonsignificant and significant at P 0.01 and P 0.05, respectively. Medium affected some characteristics. length was longer in perlite than in palm waste and the other treatments were intermediate. weight in perlite and peat was higher than in palm waste and the others were 120 intermediate (Table 10). The interaction between variety and substrate on number of fruit per plant indicated that the highest number of fruit per plant was obtained in cv. Royal

6 F. Pooyeh et al. Table 7: ANOVA effects of treatments on fruit ash, TSS, TA, carotenoids, and fruit juice ph. Source df ash (% in DM) TSS ( Brix) TA(%) Carotenoid (mg/100 g FM ph Variety (V) 2 0.52 NS 0.78 NS 0.02 NS 0.001 NS 0.09 Substrate (S) 5 1.48 NS 0.48 NS 0.005 NS 0.003 NS 0.024 NS V S 10 6.47 NS 0.41 NS 0.009 NS 0.003 NS 0.006 NS Error 36 5.94 0.45 0.01 0.008 0.02 Coefficient of variation (%) 2.69 14.27 11.5 10.86 2.23 NS, Nonsignificant and significant at P 0.05, respectively. Table 8: ANOVA effects of treatments on chemical components of fruit. Source df Antioxidant capacity (mg ml 1 ) Vitamin C (mg/100 g FM) Total chlorophyll (mg L 1 ) Total phenol (mg/100 g FM) Variety (V) 2 0.05 NS 0.06 NS 0.02 NS 0.002 NS Substrate (S) 5 0.01 NS 0.05 NS 0.0007 NS 0.0005 NS V S 10 0.03 NS 0.09 NS 0.012 NS 0.001 NS Error 36 0.09 0.2 0.15 0.002 Coefficient of variation (%) 14.94 9.24 12.69 15.72 NS, Nonsignificant. Table 9: Influence of cucumber cultivars on some vegetative and reproductive development components and some chemical components. Cultivar Internode length (cm) length (cm) volume (cm 3 ) ph Leaf DM (%) Zohal 7.57a 15.14a 58.55b 5.98a 15.33b Royal 7.73ab 14.53b 67.74a 5.88b 16.55ab Negin 6.73b 13.37c 52.15a 5.85b 18.79a Values in a column followed by the same letter are not significantly different. cultured in 100% peat substrate and the lowest value was for cv. Zohal cultured in 100% palm waste (Table 11). Root dry matter was highest in cv. Royal cul- 125 tured in 100% palm waste and lowest in cv. Negin cultured in 100% perlite (Table 12).

Growing Media in Soilless Culture of Cucumber 7 Table 10: Influence of substrate on fruit weight. Substrate weight/ plant (g) weight (g) Perlite 4230a 61.43a 7943a 60.85a Palm waste (PW) 2749a 50.61b + PW 3250a 59.15ab 3547a 57.76ab 3131a 55.97ab Values in a column followed by the same letter are not significantly different. Table 11: Influence of different substrates and cultivar interaction on number of fruit per plant. Cultivar Substrate Number fruit per plant Zohal Perlite 71.67 67.17 60.37 53.00 + PW 48.02 Palm waste (PW) 34.44 Royal 73.05 72.92 NS Palm waste (PW) 71.93 NS Perlite 71.36 NS 65.25 + PW 64.68 NS Negin Perlite 63.97 63.32 NS 51.38 + PW 50.82 NS 38.61 Palm waste (PW) 36.38 NS NS, Nonsignificant or significant at P 0.01, least squares means analysis. It is common practice to mix vermiculite, perlite, pumice, or sand with organic substrates to increased porosity and water-holding capacity (Hardgrave and Harriman, 1995). Palm waste alone and in combination with 130 perlite was tested to determine whether it affected growth and yield because it may have characteristics that could be beneficial (Ortega et al., 1996). The mix with palm waste in many instances produced results that were similar to the best results. This low-cost, widely available material can likely be mixed in media to reduce costs. 135

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