Effect of Foliar Application of Micronutrient in Combination with Urea on the Yield and Fruit Quality of Sweet Oranges

Abstract

1st year (1991-92) Study-1 Effect of urea, sodium carbonate and lime on reducing the toxicity of foliar application of micronutrients on citrus leaves were studied. A suitable concentration and pH of the solution with various precipitating agents were determined in the lab+cum field study for correction of deficiency symptoms to avoid the adverse effects of inorganic salt spray. Study-2 At Peshawar zinc foliar application significantly increased tissue zinc and corrected interveinal chlorosis and little leaf symptoms. Copper significantly increased Cu in tissue, but severely defoliated the leaves and antagonized the Zn, Mn and urea responded with improved vigor, foliage colour, greater ability to with-stand cold temperature and more yield. It was found that foliar application of Zn, Cu, Mn in concentration of 0.56, 0.13 and 0.13% respectively (on formula wt. basis (when mixed with 1% urea minimized tip burn of citrus leaves. Study-3 At Mardan using solution containing 0., 0.19 and 1.47 kg of Zn, Mn and N per hectare in 4000 L of water on elemental basis were used as a foliar application. Zinc significantly increased the zinc and nitrogen content of the leaves, Mn significantly increased the Mn and N content of leaves, Zn + Mn significantly increased the Zn and N content of the leaves and Mn and N application increased the Zn, Mn and N content of the eaves. Foliar application of Zn alone or in mixture with Mn and urea to Zn deficient trees eliminated completely Zn deficiency symptoms on the leaves. Foliar application of Zn significantly increased the yield (total yield kg/tree and ten fruit wt.) as compared to trees not sprayed with Zn. The highest yields of 92kg/tree (93% incr. over control), 76.5 kg/tree (61% incr. over control) and 67kg/tree (1% incr. over control) were obtained from trees sprayed with Zn + urea, Zn + Mn + urea and Mn + Zn respectively. With the main effect of Zn showed 45% incr. in yield as compared to yield obtained from trees where Zn was not included in the spray. The highest content of vitamin C i.e., 54.77 mg/ 100 ml juice (42% incr. over control) and 53.03 mg/100 ml juice (37 % incr. over control) were found in orange fruit sprayed with Zn and Zn + urea mixtures. The effect of foliar application of Mn to sweet orange trees on the yield was nan-significant. Colour of fruit with Mn foliar application was highly developed in all those trees given such treatment. In addition, it caused maturity in Colour increases was noted in percent of reducing and non-reducing sugar per fruit value in orange juice as compared with those values I juice from orange trees not treated with Mn. Study-4 Mean values from 147 soil/plant sample collected from citrus orchards located in NWFP showed that the soil was in general calcareous had an alkaline pH and with loam texture. Majority of the soils and citrus leaves were deficient in Zn, Cu & Mn and need application of these nutrients. A tentative mixture for curing the micronutrients deficiencies in citrus orchards is recommended to be used by the farmers. The mixture is to be prepared by dissolving 2.25. 0.5. 0.50 & 0.2, 4.0 and 0.4 kgha-1 of ZnSO4.7H2O, CuSO4.5H2O, MnSO4.3H2O, H 3BO3, Urea and Surf in 4000L of water. 2nd Year 1992-93 Study-5 During the year, 1993-93effects of foliar spray of Zn, Mn and B in the presence of urea on sweet orange cultivar ‘Blood Red’ were studies relative to yield and fruit quality, micronutrients concentration in citrus leaves and correction of deficiency symptoms at farmers orchards, Mardan.the experiment was laid out in a completely randomized design (2x3 factors factorial) with eight treatments. Each treatment was replicated three time. the experimental orchard soil was very low in organic matter, alkaline and moderately alcerous and sandy loam in nature. DTPA extractable micronutrients (Zn, Cu and Mn) and hot water-soluble boron were found deficient in the soil, but with AB-DTPA extractant Zn and Mn were deficient while Cu and Fe were found adequate. Leaf samples prior to foliar spray of Zn, Mn and B were found deficient in Zn and low in Mn contents. Boron and Cu were I optimum range while iron was in excess. Zinc, Mn and B were applied as a foliar ha-1 in the presence of 1.56 kg N (urea) and 0.4 kg surf ha-1 dissolved in 400L of water. zinc foliar spray significantly increased Zn concentration in leaves, total yield (kg per tree), the amount of ascorbic acid ad total soluble solids of sweet oranges as compared to trees not sprayed with Zn, while percent reducing a non-reducing sugar, %juice, %rag, %peel and fruit volume were unaffected with Zn foliar spray. The highest yield of 105.3 per tree (49.5 % incr. over control) was obtained from trees sprayed with Zn alone, while the main effect of Zn shows 13%increase indeed as compared with tress where Zn was not included in foliar spray. The highest mean value for Vitamin – C content (56.2 mg/100 ml) in juice was found in the trees treated with Zn+B foliar spray mixture. The highest mean value for total soluble solids (11.86) was recorded for trees spray with Zn sprayed alone. a positive interaction with Zn – B was found upon the total yield (kg/tree) of sweet oranges. Manganese’s foliar spray to sweet oranges trees significantly increased leaf Mn content, total yield and percent of non – reducing sugar as compared to trees not sprayed with Mn. The main effect of Mn showed 3.87% incr. in yield as compared with trees not sprayed with Mn. the highest percent value for non-reducing sugar (2.41) was recorded in juice for tress sprayed with Mn alone. The other quality parameters such as vitamin-C content, % acidity, fruit size and juice pH were affected with Mn spray. Boron spray significantly increased total yield of fruits (26.6% increases over control), fruit size, %juice, reducing and non-reducing sugar and percent peel, but did not influence leaf B content as compared to trees where B was not included in spray. percent acidity was significantly decreased with the application of B. Main effect of B showed 5.83% increase in yield as compared to trees where B was not included in foliar spray. The optimum yield of 89 kg trees obtained from tree sprayed with B alone, the yield was improved from 70.3- 95.7 kg/tree (36.13% incr. over control), when B applied was applied in combination with Zn, the maximum fruit size 6.2 cm and highest percentage of juice (70.03%), were recorded in those treatments sprayed with B alone as compared to control and otter treatments, while percent acidity of the fruit was significantly REDUCED FROM 0.89-0.60% as compared to control. The optimum yield and better fruit quality in term of vit – C, sugar content, percent juice and tall soluble solids were obtained by the combined effects of Zn+B which was followed by was foliar spray mixture. However, maximum yield with maximum VCR and net return of Rs. 59722.02 was obtained with only zinc application. Study-6 Another experiment of similar nature and o identical condition was conducted. Citrus leaves before foliar spray showed that Zn and B were low, Mn and Cu were optimum while Fe was ibn excess. Foliar spray of Zn when applied alone significantly increased the Zn concentration up to 87.33 mg/kg. however, it is significantly decreased the concentration of Mn in citrus leaves zinc flair spray significantly increased the total yield, vit-c content and Fruit size, the highest yield 23.30 sprayed with was, followed by 115.3 kg/tree (83% incr. ore control) from trees sprayed with Zn+B. the highest content of vit. C, i.e., 52.36mg/100 ml f juice (22.58% incr. obey the control) was obtained from trees sprayed with Zn + B. zinc effect other quality parameters i.e.; % juice, % rag, % peel, total soluble solids, reducing sugar, non-reducing sugar, %acidity, juice pH & volume of fruit was non-significant. foliar spray of Mn significantly increased the Mn concentration of citrus leaves up to 85.87 mg/kg, but significantly decreased the Zn concentration of citrus leaves. It significantly increased the total yield and reducing sugar, but significantly decreased %peel of citrus fruit. effect of foliar spay spray of Mn on other quality parameters i.e., % juice, %rag, vitamin C, non-reducing sugar, total soluble solids, %acidity, juice ph., volume and size of fruit was non-significant. Foliar spray of B did not significantly affect the B concentration in citrus leaves when it was applied alone. foliar spray of B had no significant effect on citrus yield while it significantly increased the %juice and decreased the %peel of citrus fruit. The highest %juice of 62.59 for citrus fruit was obtained for trees sprayed alone with B on other quality parameters i.e., sugar reducing, non- reducing sugar, total soluble solids, % acidity, vitamin C, juice pH, volume and size of citrus fruit was non-significant. The most economical and maximum fruit yield per tree, minimum % peel an optimum vitamin C were obtained with foliar application o was with tis treatment a maximum VCR with a net return of Rs. 64490.44 was obtained. The next economic and higher fruit yield per tree, maximum vitamin- C, maximum fruit size and minimum p% peel were outlined with Zn+B application. Study-7 Another study was also conducted with same design/doses at Agricultural Research Institute Tarnab, Peshawar, the yield and fruit quality data could not be recorded due to un planned removal of citrus orchard by the institutional authority. Study-8 For critical levels of Zn, Mn and B in citrus leaves, three years data (Three field experiments) were used. critical levels of Zn, Mn and B in citrus leaves were to be found to be 33, 28 and 37 mg/kg respectively. These values could be used for estimating deficiencies of Zn, Mg and B citrus leaves. 147 each soil and citrus leaf samples were analysed which showed that these soils were in general calcareous had an alkaline pH am with varied texture. DTPA extractable Cu and Mn were adequate in all soil samples. Zn was low in 31.3%, marginal in 46.3% and adequate in 22.4%. Fe was low in 3.4% marginal in 25.2% and equate in 71.4 % soils. AB-DTPA extractable Cu was owing 2.4%, adequate in 97.6%, Zn was low 38.1%, marginal in 23.78% and adequate 38.1%, Fe was low in 3.3 % marginal 13.6% and adequate in 63.1% and Mn was adequate in 100% soil samples. Hot water-soluble boron was deficient in 61.225 soil and marginal in the rest of soil samples. In citrus leaves Zn, Cu, Mn and B wee found deficient in 53.1, 58.5, 60.5 and 57.14% respectively, while Fe was found. 3rd year study 1993-94 Study-9 During the year 1993 sixty representative soils and their associative leave samples are collected from their various orchard to find out the micronutrient contents. Classification of soil and leaf samples into deficient and sufficient were made on the basis of critical levels. DTPA extractable Zinc range from 0.10- 1.15mg/kg with a mean value of 0.68mg/kg out of total sixty soil samples 33.3% were found deficient and 60 were found marginal at Zinc content. Zinc gives a negative non-significant correlation with soil pH and positive with soil organic metal EC. Zinc gave a negative significant correlation with soil lime. DTPA extractable Mn ranged from 0.17- 14.37 mg/kg with a mean value of 4.2 mg/kg, Magnesium was found adequate in all soil samples. Magnesium gave positive non-significant with soil pH and organic matter and negative non-significant correlation with soil lime. Its relation with soil EC was positively significant DTPA extractable Fe content of soil ranged from 1.72 – 25.38 mg/kg with a mean value of 5.69 mg/kg. out of 60 soil samples 10% were found deficient and 55 were found marginal in DTPA extractable Fe. Iron gives a negative significant correlation with soil Ph and lime and negative non-significant correlation with soil ph. and lime and non- significant correlation with soil organic matter. Its relation with soil EC was positive but non serious DTPA extractable Cu of soil Range from 0.14- 1.80 with a mean value of 0.92 mg/kg. out of 60 soil samples 98.3 were found adequate and 1.67 were found deficient in Cu. It gave negative non-significant correlation with soil ph. and lime and positive non-significant correlation with soil EC. Its relation with soil organic matter was positive and significant. AB-DTPA extractable Zn of the soil ranged from 0.27-5.07 mg/kg with mean value of 1.18 mg/kg. out of 60 soil sample 71.7 were found deficient and 10% were found marginal in Zn content it gave negative significant correlation with soil EC organic matter. AB-DTPA extractable Mn ranged from 0.21-2.85 mg/kg with ameen value of 0.93 mg/kg. out of 60 soil sample 36.7% were found deficient and 63.3% were found adequate in Mn content. it gave negative non-0significant correlation with oil pH and positive non-significant correlation with soil organic matter. It gave negatively significant correlation with soil lime a positive significant correlation with soil EC. AB-DTPA extractable Fe of the soil ranged from 1.22- 16.52 mg/kg with a mean value of 7.17mg/kg. out of 60 oil samples 96.7% were found adequate and 3.3% were found efficient in Fe content. It was non-significantly and positively correlated with oil organic matter and positively non significantly correlated with soil EC. It gave negative significant corelation with soil lime and soil ph. AB-DTPA extractable Cu ranged rom 1.0 to 1.86 mg/kg with a mean value of 3.58 mg/kg. out of total 60 soil samples 95% were fund adequate and only 5% were found deficient in Cu content. it gave positive non-significant correlation with the soil organic matter and EC. its relation with the soil lime and ph. was negative non-significant. Hot water-soluble boron of the soil ranged from 1.14-0.90 mg/kg with a mean value of 0.41mg/kg. out of 60 samples of soils 80% were found f=deficient and none of them was in excess of HWS-B. In citrus leaves the Zn concentration ranged from 8.1-68.4 mg/kg with a earn value of 16.82mg/kg. Out of the 60 examples 78.3 % were found deficient in Zn content. manganese’s in citrus leaves raged from 0.60-11.65 mg/kg with a mean value 5.33 mg/kg. out of 60 leaf samples 60% were fund deficient in Mn content. Iron content of citrus raged from 1750-693.50 mg/kg with a mean value of 162.20 mg/kg. out of 60 leaf samples 1.7% were found deficient and 98% were found optimum and high in Fe content. Copper content of the citrus leaves ranged for 9.40-37.55 mg/kg with a earn value of 16.55 mg/kg. out of 60 samples 56.6% were found optimum and 26.7% were found low and 16.7% deficient in Cu content. Boron content of citrus leaves ranged from 10.0-34.00 mg/kg with a mean value of 20.05 mg/kg. out of 60 leaf samples 56.7 were found deficit and 5% were found marginal in B content. Study-10 Previous study 5 on micronutrient application was modified by including additional copper in the presence of urea and sweet orange (Blood red) was conducted on farmers orchards at Marden during the 1993-94, in order to study the effects of Zn, Mn, B and Cu spray on correction of deficiency symptoms. Effects on nutrient status of leave, yield and fruit quality. He experiments was laid out in a Randomized complete block design (RCBD) with 10 treatments. Each treatment was explicated 3 times. Zn, Mncube and B corrected the respective deficiency symptoms of the eaves and improved the general growth of the trees. Leaf samples collected prior t foliar spray of Zn, Mn and B were found deficient in Zn and low in Mn cent. Boron was optimum, Cu was excess while Fe was in high range (Division of Agric. Sci. Univ. of California, 1981). Zn and Mn foliar spry significant incr. their respective micronutrients in the leaves while B and C foliar spray did not significantly affect the B and Cu concentration of citrus leaves after foliar spray. Total yield (kg/tree) and percent juice was significantly increased with all e foliar spray of micronutrients. However maximum yield (62.67kg/tree) was obtained with the combined effect of obtained (T10), while maximum juice content (64.15%) was obtained with the combined effects of Zn+B (T7). Reducing sugar and total soluble solids were also significantly increased specially with the application of obtained (T10). the maximum value for vitamin – c content (61.87 mg/100ml) was recorded by the combinate effects of Zn+Mn (T6). percent peel and percent acidity were significantly reduced from 36 to 27.72 and 0.89 to 0.64 with the application of Zineb and B spray respectively. the otter quality parameters such as percent rag, value, size and juice pH were found non-significantly. For maximum production good tree vigor and better fruit quality sweet oranges. A combination of Zn+Mn+B+Cu should be applied by the farmers through foliar spray annually 3 times with an interval of 15 days between two consecutive sprays at appropriate times. The economics fertilizers reveals that each fertilizer whether applied alone or in combination gave an economical VCR. However, the combination of Zn+Mn+B+Cu were found to be more economical and causes no toxicity to citrus pant. Study-11 This study was conducted with similar doses/design but at different location. Leaf samples collected before foliar spray were found low in Zn and Mn content. Boron and Cu was optimum while Fe concentration was found in excess (Division of AGRIC. Sci. Univ. of California, 1981) zinc and Mn contents in citrus leaves were significantly increased with the application of Zn and Mn while the concentration of Cu was found non-significant after foliar spray of B and Cu. Foliar spray mixture of Zn+Mn+B+Cu significantly increased total yield (kg/tree), percentage of juice, fruit size, Vitamin – C in juice and total soluble solids. Maximum yield of 6.67 kg/tree and vitamin-C (56.63 mg/1000ml) was obtained by combined effects of Zn+Mn+B+Cu (T10) while max. juice contents (64.40%) in the treatments sprayed with Zn+Mn+Cu (T9). maximum fruit size (6.6 cm) and highest value for reducing sugar (4.58%) was recorded with Zn and B spray alone. Percent peel was significantly reduced from 40.32 to 29.37 % with the application of Zn+B (T7). The other quality parameters such as 5 fruit weight, %rag, %acidity, volume and juice pH, were unaffected wit foliar spray of micronutrients. the results of economic analysis showed that each micronutrient alone or in combination gave maximum VCR. The combination of Zn+Mn+B+Cu in foliar spray mixture were found more economical and beneficial with respect to yield, tree vigor and fruit quality. Study-12 On the basis of three years filed data (five field experiments) the critical levels of Zn, Mn and B in citrus leaves (Blood RED varsity) were modified and found to be 40, 28and 40 mg/kg respectively. Theses carnival values will be of great help and will determine the sufficiency/deficiency levels in citrus leaves. From study 10 and 11 it was concluded that Zn (0.44%), Mn (0.19%), B (0.05%) and Cu (0.07%) on formula basis in the presence of urea (0.85%) and wetting agent (surf) 0.1% gave effective curing of deficiency symptoms on citrus leaves gave ore yield and improved fruitsquality parameters by adopting the technology developed during this react. This socio-economic citing of the citrus growers could be greatly improved. For the benefit of farmers three extensions bulletins, 2000 each in number were published and by Out Reach Directorate, NWFP Agricultural University, Peshawar. From this project 4 research papers were submitted to various national research journal, out of which two were published by Sarhad Journal of Agriculture. One paper was presented invitational seminar held at Faisalabad. In addition to the above 10 M.Sc. (hons) students have completed their thesis as a part of this projects.