Symposium no. 15 Paper no. 2151 Presentation: poster The effectiveness of different application methods of zinc sulfate on nutritional conditions of apple in calcareous soils of Iran RASOULI SADAGHIANI M.H. (1), MALAKOUTI M.J. (1) and SAMAR S.M. (2) (1) Dept. of Soil Science, School of Agriculture, Tarbiat modarres University, P.O. Box 14115-111, Tehran, Iran (2) Soil and Water Research Institute, North Kargar Ave., P.O. Box 14155-6185, Tehran, Iran Abstract To evaluate the effectiveness of the different application methods of zinc sulfate in apples, an investigation was carried out in one of the orchards of West Azerbaijan province in 2000 growing season. The treatments with five replications were tested: T1; control, T2; balanced fertilization based on soil test except zinc application, T3; T1+trunk injection of zinc (1.0%), T4; T2+trunk injection of zinc, T5; T1+zinc broadcast, T6; T2+zinc broadcast, T7; T1+zinc spray (0.5%), T8; T2+zinc spray, T9; T1+deep placement of zinc and T10; T2+deep placement of zinc. Analysis of soil tests from 0-30 cm and 31-60 cm depths indicated that the level of soil fertility was low and the concentration of several nutrients were about or below the critical level. The zinc concentration from both soil layers were 0.2 mg kg -1, indicating a sever deficiency of this element resulting from its continuous uptake without supplementing it. The analysis of the irrigation water showed high levels of bicarbonates. The results demonstrated that the greatest leaf area, chlorophyll index of leaves resulted from deep placement and spray treatments. Also the effect of zinc on the levels of the current year s growth of branches was significant and spray of zinc appeared to be the most effective method in this respect. The zinc concentration in the samples from the control plants were low (15 mg kg -1 ) and it was below the critical level so that trees showed sever deficiency symptoms. The foliar application of zinc sulfate resulted in high levels of zinc in the leaves, but a great percentage of this supplement remained in the leaf epidermis as well as in the dead spaces between the leaf cells instead of being carried to other plant tissues. The concentration of P, Ca, were low in the samples from spray treatments, most probably due to antagonistic reactions between zinc and these elements. The effects of these fertilizer treatments on the concentration of N, K, Mg, Fe, Mn, Cu and B were statistically insignificant. The chemical analysis of the fruits showed high levels of N from spray treatments, which were correlated with high levels of zinc in the same samples due to direct spraying of fruits. The Ca levels of sprayed fruits were low. Other quality factors such as TSS, acidity level, sugar content and ph of the fruit juice were not affected by zinc sulfate. However, balanced fertilizer treatments especially deep placement along with spray application of zinc sulfate, resulted in improvements in apple quality indices. 2151-1
Considering soil condition (calcareous) and the obtained results, it appeared that the placement of zinc sulfate in the holes along with manure was the best method of zinc application in apple orchards. Keywords zinc, spray, trunk injection, deep placement and apple Introduction Apple (Malus domestica) trees as any other plant require certain climatic, soil and nutritional conditions to successfully produce a commercial crop. If one of these conditions not met, the crop is reduced and tree health suffers. In the case of fruit trees, some of these conditions may be modyfied. Nutrient imbalances may manifest themselves in fruit crops more than in any other group of economic plants. The nutritional status of fruit tree can be alleviated by foliar nutrient sprays or, sometimes by adding fertilizers to the soil in different ways. One aspect is the limiting mineral nutrient and its absorption restrictions that exist through the roots and/or the leaves (Arce et al., 1992). Zinc (Zn) availability to plats is reduced in high ph soils. Two main theories are offered to account for high Zn deficiency incidence on calcareous soils. First, the solubility of Zn in these soils decreases up to 100 fold per unit increase in ph. The second theory is based on the absorption of this element by calcium carbonate (CaCO 3 ). The carbonate found in such soil forms an insoluble complex with Zn added as zinc sulfate (ZnSO 4 ). Zinc deficiency in soils has been reported worldwide. In a global study initiated by FAO and carried out in 30 countries, it was estimated that about 30% of the agricutural soils of the world are Zn-deficient (Cakmak et al., 1997). Iran soils, based on the analysis of more than 250 soils samples, were also classified as Zn-deficient (Malakouti et al., 2000). Zn deficiency is common in apple, especially on trees grown in alkaline soils. The visual symptoms of Zn deficiency are variously described as rosette, yellows, little leaf and crinkled leaves. Zinc fertilization of apple trees in the calcareous soils of Iran is a well-known and necessary cultural practice, particularly for established orchards. But the proper methods of zinc application are less well-known. Foliar spraying apple trees with zinc sulfate in autumn, or dormant-season spraying dose not increase leaf Zn, but placement of zinc sulfate in holes 30-60 cm from the trunk at the time the apical bud bursts, increase leaf Zn in the early spring growth (Orphanos, 1982; Bahadur et al., 1998). Pavan (1998) found that placement of zinc fertilizer in holes significantly ameliorate zinc deficiency symptoms and increase yield of apple. Also its residual effects last until the end of five years experiments, however surface zinc treatment is not effective. Soil application of zinc have not been effective except with young trees, where applications have been worked into the soil prior to tree planting (Peryea and Williams, 1996). Apple fruit set increase by foliar sprays containing N, Mg, Zn and B. The ZnSO 4 sprays also increase the number of fruit buds, but reduce fruit set so that do not affect on apple yield (Yogaratnam et al., 1982). Trunk injection is an alternative application method for introducing chemical compounds into trees. Several injection methods, including trunk infusion, bark banding and pressurized trunk injections have been devoloped since the beginning of the century (Navarro et al., 1992). Trunk injections of 2151-2
ferrous compounds alleviate successfully iron chlorosis in olive and peach trees (Fernandez-Escobar et al., 1993). The objective of this study was to test the effectiveness of different application methods of zinc sulfate on apple orchards of Salmas region. Materials and Methods An investigation was carried out in one of the orchards of Salmas, West Azerbaijan, in 2000 growing season. The experimental design was a randomized complete block with five replications (one tree per replication). Ten treatment were tested: T1; the grower s conventional fertilization (control), T2; balanced fertilization based on soil test except zinc application, T3; T1+trunk injection of zinc (1.0%), T4; T2+trunk injection of zinc (1.0%), T5; T1+zinc broadcast, T6; T2+zinc broadcast, T7; T1+zinc spray (0.5%), T8; T2+zinc spray, T9; T1+deep placement of zinc and T10; T2+deep placement of zinc. T1, farmer conventional fertilization (1.0 kg tree -1 urea and 0.5 kg tree -1 triple super phosphate) as control. T2, involved 1.500 kg tree -1 NH 4 NO 3, 0.300 kg tree -1 triple super phosphate, 1.0 kg tree -1 K 2 SO 4, 1.000 kg tree -1 S, 0.350 kg tree -1 MgSO 4, 0.350 kg tree -1 FeSO 4, 0.100 kg tree -1 MnSO 4, 0.050 kg tree -1 CuSO 4 and 0.050 kg tree -1 H 3 BO 3. In trunk injection treatments, 400 ml ZnSO 4 (1.00%) solution introduced from trunk above 30- cm soil surface. The injection apparatus consists; injection pump for insertion of solution into the tree trunk after a hole (0.5 cm in diameter and depth of 5 cm) has been mechanically drilled. Soil application of ZnSO 4 (broadcast and deep placement methods) involved 1.00 kg tree -1 ZnSO 4 which in broadcast treatments mixed completely with surface soil and in deep placement treatments used in 4 holes of 50 cm diameter and 40-50 cm depth under tree canopy. Foliar sprays of ZnSO 4 (0.5%) included; dormant spray, 4 week after full bloom and 8 week after full bloom. The physio-chemical characteristics of the soil of the experimental field were; ph=8.2, CaCO 3 = 12.5%, clay=48%, EC=1.04 dsm -1, organic carbon (C)=0.83%, P=2.2 mg kg -1, K= 205 mg kg -1, Zn = 0.2 mg kg -1, Fe= 4.8 mg kg -1, Mn= 3.5 mg kg -1 and Cu= 1.5 mg kg -1. Chemical characteristics of irrigation water was; ph= 7.5, HCO - 3 =4.8 meq L -1, Cl - = 1.7 meq L -1 2-, SO 4 = 1.0 meq L -1, Ca 2+ = 2.0 meq L -1, Na + =2.38 meq L -1, EC= 0.710 ds m -1 and sodium adsorption ratio (SAR)= 1.5. Fifty leaves from all plots were sampled for analysis late July and ten apples were randomly sampled from each replication and each treatment. Fruit juice and ash were analyzed for different nutrient using standard procedures. Results and Discussion The results of soil tests showed that the level of soil fertility was low and the concentration of several nutrients were about or below the critical level. The zinc concentration from both soil layers were 0.2 mg kg -1, indicating a sever deficiency of this element resulting from its continuous uptake without supplementing it. The analysis of the irrigation water showed high levels of bicarbonates. Leaves from ZnSO 4 sprayed treatments had significantly higher Zn (Table 1). The zinc concentration in the samples from the control plants were low (15 mg kg -1 ) and it was below the critical level so that trees showed sever deficiency symptoms, including little leaf, rosette and crinkled leaves. 2151-3
Table 1 Effect of different treatments of zinc sulfate on leaf nutrient compositions. Treatment Percent (%) mg kg -1 N P K Ca Mg Fe Zn Mn Cu B T1 2.16 0.28 2.14 1.62 0.54 169 15.08 39 7 82 T2 2.22 0.27 2.12 1.70 0.61 159 15.80 57 8 96 T3 2.26 0.32 2.12 1.58 0.61 179 28.20 57 7 93 T4 2.20 0.28 2.69 1.74 0.62 154 32.20 51 8 98 T5 2.18 0.29 2.38 1.84 0.61 175 27.40 42 8 86 T6 2.24 0.28 2.26 1.70 0.65 162 32.40 55 8 87 T7 2.20 0.29 2.24 1.50 0.57 148 160.0 46 8 84 T8 2.20 0.26 2.06 1.48 0.61 137 171.0 52 7 83 T9 2.20 0.28 2.20 1.80 0.60 177 41.00 52 7 86 T10 2.24 0.27 2.10 1.70 0.57 162 20.60 69 8 77 Result NS * NS * NS NS ** NS NS NS NS: Not Significant *: Significant (P= 0.05) ** : Significant (P= 0.01) The foliar spray of zinc sulfate resulted in high levels of Zn in the leaves, however as toxicity symptoms (leaf burn or fruit russet) were not observed, it seems a great percentage of this supplement remained in the leaf epidermis as well as in the apoplast and dead spaces between the leaf cells, instead of being carried to other plant tissues. The concentrations of P, Ca, were low in the samples from spray treatments, most probably due to antagonistic reactions between zinc and these elements. The effects of these fertilizer treatments on the concentration of N, K, Mg, Fe, Mn, Cu and B were statistically insignificant. Zinc treated trees had greater leaf area, chlorophyll index and current year s growth of branches than control trees (Table 2). He and Sparks (1991) found that chlorophyll concentration increased with leaf Zn, corresponding to morphological observation that leaf chlorosis decrease with increasing leaf Zn. Table 2 Effect of different treatment of zinc sulfate on leaf area, chlorophyll index and current year s growth of branches. Treatment Leaf area (cm 2 ) chlorophyll index (SPAD) current year s growth (cm) T1 19.07 33.00 20.43 T2 23.40 34.66 23.20 T3 36.32 40.74 27.28 T4 39.07 41.40 30.93 T5 31.68 37.48 26.82 T6 34.52 40.32 32.52 T7 34.10 38.38 31.82 T8 40.61 39.76 34.69 T9 34.42 37.50 26.05 T10 44.62 42.88 32.38 Result ** ** ** **: Significant (P= 0.01) 2151-4
The chemical analysis of the fruits showed high levels of N from spray treatments, which were correlated with high levels of zinc in the same samples due to direct spraying of fruits. The Ca levels of sprayed fruits were low. Other quality factors such as TSS, acidity level, sugar content and ph of the fruit juice were not affected by zinc sulfate. However, balanced fertilizer treatments especially deep placement along with spray application of zinc sulfate, resulted in improvements in apple quality indices. Conclusions All different application methods increased the leaf Zn content. Deep fertilizer placement resulted in the optimum rates of nutrients uptake by apple trees because of the absence of calcareous conditions, creation of acid environment (due to S fertilization and animal manure adding) and good aeration. Appropriate conditions and better aeration in holes (placement treatments) improved growth indices and leaf and fruit contents of micronutrients particularly Zn and Mn. Although spray application of Zn can alleviate deficiency symptoms in emergency times (sever deficiency), it must be replicated. But frequency of Zn spraying or application of high concentrations, like other nutrients spraying, i.e. Ca (Malakouti et al., 1999) may cause foliage injury and/or russet in fruit skin, as it was seen in some spray treatment plots, therefore spray application of zinc sulfate in low concentration especially after bud opening and during growing season is recommended. Many factors may affect uptake of injected solutions, including environmental conditions, the chemical used and the injector system (Reil, 1979). Many fruit trees have been injected successfully with the use of this technique, however, the commercial use of the injection system is limited because the equipment is not widely available and labors cost are high. In addition, injuries around the injection holes have been noted, especially when pressure were very high (Sach et al., 1977). Therefore considering soil condition (calcareous) and the obtained results, it appeared that the placement of zinc sulfate in the holes along with manure was the best method of zinc application in apple orchards of West Azerbaijan. Acknowledgements Authors wish to express their sincere appreciation to E. Sepehr, S. Fekri and M. Afkhami stuff members and researchers of Soil and Water Research Institute (SWRI), B. Rasouli, H. Zamanejou, M. Arzanlou, M. A. Rezaee and all scientific members of the Soil and Water Research Institute of Iran for their assistance s help in preparing this paper. References Arce, J.P., J.B. Storey and C.G. Lyons. 1992. Effectiveness of three different zinc fertilizers and two methods of application for the control of little-leaf in peach trees in south Texas. Commun. Soil Sci. Plant Anal. 23(15,16):1945-1962. Bahadur, L., C.S. Malhi and Zora Singh. 1998. Effect of foliar and soil application of zinc sulphate on zinc uptake, tree size, yield and fruit quality of mango. J. Plant Nutr. 21(3):589-600. Cakmak, I., A. Yilmaz, M. Kalayci, H. Ekiz, B. Torun, B. Erenoğlu and H.J. Braun. 1996. Zinc deficiency as a critical problem in wheat production in Central Anatolia. Plant and Soil 180:165-172. 2151-5
Hu, H. and D. Sparks. 1991. Zinc deficiency inhibits chlorophyll synthesis and gas exchange in Stuart pecan. HortScience 26(3):267-268. Malakouti, M.J., A. Shahabi, P. Keshavarz, A. Golchin, A. Bybordi and A. Majidi. 2000. Effects of zinc sulfate treatments on apple yield and growth. J. Soil and Water Research Inst. (perssian). 12(8):1-9. Malakouti, M.J., S.J. Tabatabaei, A. Shahabi and E. Fallahi. 1999. Effects of calcium chloride on apple fruit quality of trees grown in calcareous soil. J. Plant Nutr. 22 (9):1451-1456. Navarro, C., R. Fernandez-Escobar and M. Benlloch. 1992. A low pressure, trunk injection method for introducing chemical formulations into olive trees. J. Amer. Soc. Hort. Sci. 117(2):357-360. Orphanos, P.I. 1982. Spray and soil application of zinc to apples. J. Hotr. Sci. 57 (3):259-266. Pavan, M.A. 1998. Response of apple to soil applied zinc. Pesquisa Agropecuaria Brasileira 33(8):1255-1260. Peryea, F. and K. Williams. 1996. Nutrient sprays. WSU-Tree Fruit Research & Extention Center. Reil, W.O. 1979. Pressure-injecting chemicals into trees. Calif. Agr. 33:16-19. Sach, R.M., G. Nyland, W.P. Hackett, J. Debie and G. Giannini. 1977. Pressurized injection of aqueous solutions into tree trunks. Scientia Hort. 6:297-310. Yogaratnam, N. and D.W.P. Greenham. 1982. The application of foliar sprays containing nitrogen, magnesium, zinc and boron to apple trees: I. effects on fruit set and cropping. J. Hort. Sci. 57(2):151-158. 2151-6