ارزيابي و تعيين وضعيت تغذيه¬اي باغات پرتقال رقم والنسيا در جنوب استان فارس

Evaluationand Determinationthe Nutritional Status of Valencia Orange Orchards in South of Fars Province

با استفاده از روش¬های تشخیص چندگانه4 و تجزیه آماری چند متغیره5 وضعیت تغذیه¬ای باغات پرتقال رقم والنسیا در جنوب فارس مطالعه شد. برای این منظور تعداد 80 باغ پرتقال رقم والنسیا انتخاب و 30 درخت از هر باغ انتخاب ونشانه¬گذاری شدند. در فصل مناسب با انجام نمونه¬برداری از درخت‌های انتخاب شده، غلظت عناصر در نمونه¬های گیاهی تعیین و در فصل برداشت، میانگین عملكرد هر باغ اندازه¬گیری شد. نتایج نشان داد كه 11 باغ جزء گروه عملكرد زیاد و 69 باغ دارای عملكرد كم بودند و میانگین عملكرد¬های مطلوب، 113 كیلوگرم بر درخت، به عنوان عملكرد هدف تعیین شد. از میانگین اعداد بدست آمده¬ی عناصر غذایی برای جامعه¬ی با عملكرد بالا، غلظت¬های مطلوب 10 عنصر مورد بررسی به دست آمد كه شامل نیتروژن 18/0± 00/3 درصد، فسفر01/0± 17/ 0 درصد، پتاسیم12/0± 37/1 درصد، كلسیم 78/0±32/3 درصد، منیزیم07/0± 36/0 درصد، منگنز 35/3 ± 0/23 میلی¬گرم در كیلوگرم، روی3/2 ± 3/17 میلی¬گرم در كیلوگرم، آهن 3/7± 75 میلی¬گرم در كیلوگرم، مس 44/1± 81/7 میلی¬گرم در كیلوگرم و بور 4/19±76 میلی¬گرم در كیلوگرم بود. با مقایسه با اعداد مرجع به دست¬آمده برای باغات با عملكرد مطلوب، بیش از 50 درصد باغات مورد ارزیابی مقادیر نیتروژن، كلسیم و منگنز آنها كمتر از عدد مرجع به¬دست¬آمده بود و غلظت بور در گروه باغات با عملكرد بالا بیش از 50 درصد كمتر از باغات با عملكرد پایین بود كه نشان¬دهنده محدودیت این عنصر در گیاه برای عملكرد است. همچنین، نتایج تجزیه آماری چندمتغیره و تجزیه به مولفه-های اصلی6 نشان داد كه عناصر نیتروژن، كلسیم، آهن و روی به ترتیب بیشترین اثر را بر تغییرات عملكرد داشتند.

Introduction: Fertilizer recommendation in orchards based on soil testing is not accurate because findings showed that there is not significant correlation between nutrients concentration in the soil and plant. Therefore, studying the nutritional status in orchards is usually based on the plant testing. In order to evaluate the nutritional status ofplants, different methods, such as Compositional Nutrients Diagnosis (CND), Diagnosis and Recommendation Integrated System (DRIS), Deviation from Optimum Percentage (DOP), Critical Value Approach (CVA) and Sufficiency Range Approach (SRA) were used. In the CND method, a determination coefficient measured which is considered as the relative superiority of this method to the others. Generally, through the CND method, a correct perception on nutritional status of plantsmay be obtained. Materials and Methods: The nutritional status of orange orchards, Valencia cultivar, in south of Fars province (Darab town) was studiedusing the compositional nutrient diagnosis and multivariate statistical analysis methods. For this, 80 orange orchards, Valencia cultivar were selected and 30 trees in each orchard were signed. Plant samples were taken from the selected trees in the proper session and concentration of N, P, K, Ca, Mg, Mn, Zn, Fe, Cu and B weremeasured using the standard methods. Then the average yield was measured atharvest. Based on the CND method, total concentration of the nutrients in the plant was considered as a variable (Sd) plus a residual portion (Rd) that "d " is defined as the number of nutrients in the equation and Rd is defined as the residual value. Which sum of the equation equals 100 and it is based on percent. The residual/un measured nutrients and estimated by using the equation of " Rd = 100- (N+P+K+…) ". Thereafter, by using the standard equations, which they were perfectly explained and presented in the material and methods section, the geometric mean of nutrients, nutrients index, nutrient balance index, and average yield and finally the reference norms were determined. In addition to the CND method, by using the Multivariate Statistical Analysis and PrincipalComponent Analysis methods, the effective and important nutrients in the yield were determined and also, ability of the CND method was evaluated. The SPSS software was used for variance analysis the data. Compositional nutrient diagnosis (CND) analysis and multivariate analysis methods are used to study the nutritional diagnosis of Valencia orange orchards in south of Fars province. 80 valencia orange orchards were selected in the region and in each of them, 30 uniform trees were marked and sampled were taken in proper time and referenced method. Leaf elemental compositions and mean yield also were measured from selected trees for each orchard. Data analysis divided all orchards into two low and high yield groups. Results and Discussion: The results showed that 11 orchards were as high yielding group and 69 orchards were as low yielding group and the average of optimum yields, 113 Kg tree-1, was determined as the yield goal. By using the average of measured nutrients norms for the high yielding community the concentration of the 10 studied elements was obtained which comprised: N 3.00± 0.18; P 0.17± 0.01; K 1.37± 0.12; Ca 3.32± 0.78; Mg 0.36±0.07; Mn 23± 3.35; Zn 17.3± 2.3; Fe 75± 7.3; Cu 7.81± 1.44; B 76± 19.4. Through comparison with the obtained reference norms of optimum yielding orchards, more than 50% of the studied orchards had lower N, Ca and Mn content than the obtained norm and B concentration in the high yielding group was more than 50% less than the low yielding group. Generally, the results of Multivariate Statistical Analysis and PrincipalComponent Analysis showed that N, Ca, Fe and Zn had the highest effect in changes of yield. Conclusion: Resultsof this work showed that 13% of the studied orchards were in the high yielding group and 86% of themwere in thelow yielding group which shows the imbalance nutritional condition in the studied region. The positive effect of N and Ca on the yield may be due to the dilution effect which these nutrients can reduce the B toxicity. Abundance of Mn deficiency in the studied orchards may be due to the high concentration of Zn and Fe in the plants and antagonistic relations may be considered as the main reason. Multivariate statistical analysis methods may be used as an important tool to study the nutritional conditions of plants. Dominant percentage of the studied orchards showed low yield which may be due to the B toxicity which probably N and Ca application may be alleviated the negative effect of this element.