اثر محلول‌پاشی نفتالن ‌استیک اسید و کارباریل و تغذیه برگی اوره و سولفات منیزیم بر کاهش تناوب باردهی نارنگی کینو در منطقه دزفول

این پژوهش به منظور امکان کاهش تناوب باردهی نارنگی کینو در منطقه دزفول در قالب دو آزمایش اجرا گردید. در آزمایش اول به منظور افزایش محصول درختان نارنگی کینو در سال کم‌ بار، اقدام به تغذیه برگی درختان با استفاده از محلول‌پاشی کودهای اوره با غلظت های صفر، سه و پنج در هزار و سولفات منیزیم با غلظت های صفر، یک و سه در هزار و ترکیب سطوح اوره و سولفات منیزیم در اوایل ماه های دی، بهمن و اسفند سال پربار (1396) گردید. در آزمایش دوم جهت بررسی امکان کاهش تناوب باردهی نارنگی کینو در سال پر بار، از محلول‌پاشی هورمون نفتالین استیک اسید (naa) در غلظت های صفر، 200،  300 و 400 میلی گرم در لیتر و غلظت های صفر، 700، 1200 و 1700 میلی گرم در لیتر کارباریل در مرحله 40 روز بعد از تمام گل در سال پربار (1397) استفاده شد. نتایج نشان داد بیشترین میزان عملکرد درختان در سال کم بار مربوط به محلول‌پاشی با کود اوره به نسبت سه در هزار + سولفات منیزیم به نسبت یک در هزار در اوایل ماه بهمن سال قبل (پربار) است و توانست تناوب باردهی را نسبت به درختان شاهد به میزان قابل قبولی کاهش بدهد (10.78 کیلوگرم افزایش محصول). نوع کود بر ویژگی های کیفی میوه تاثیر نداشت اما زمان محلول پاشی بر میزان اسید میوه تاثیر داشت به طوری که بیشترین و کمترین میزان اسید میوه به ترتیب مربوط به محلول پاشی در ماه های دی و بهمن بود. بر اساس نتایج ترکیب کارباریل قادر به کاهش تناوب باردهی در مرحله 40 روز بعد از تمام گل در درختان نارنگی کینو در منطقه دزفول نبود. در بین غلظت های مختلف naa، محلول‌پاشی naa با غلظت 200 میلی گرم در لیتر با کاهش 36.5 درصدی در میزان عملکرد به نحو متعادل تری تناوب باردهی را کاهش داد و تفاوت معنی داری با درختان شاهد داشت.

Effect of foliar application of Naphthalene acetic acid and Carbaryl and leaf nutrition of urea and magnesium sulfate on alternate bearing reduction of Kinnow mandarin in Dezful region

Introduction: Kinnow mandarin is a high yield cultivar that has special importance due to its interesting flavor and high tolerance againts high temperature conditons (Nawaz et al., 2008). Unfortunately, it has alternate bearing habit that affecteing its economic efficiency (SafaeiNejad et al., 2015) . Foliar application of fruit thining compounds and nutrientes in onyear could be efective to adjust alternate bearing in fruits (Rabe, 1994; SafaeiNejad et al., 2015; Sebastian et al., 2019). This research was carried out in order to the evaluation of the possibility of alternative bearing adjustment of Kinnow mandarin using foliar application of thinning compounds and nutrients in Dezful region of Iran. Material and methods: To cope with alternative bearing problem of Kinnow mandarin trees in Dezful region of Iran, two separate experiments were conducted during 2018. In the first experiment, in order to increase the yield of Kinnow mandarin trees in offcrop year, the trees were treated with foliar application of urea (0, 0.3 %, and 0.5%) and magnesium sulfate (0, 0.1%, and 0.3%) fertilizers and the mixture of them in the early of January, February and March in oncrop year. In the second experiment, trees were treated by spray application of Naphthalene acetic (NAA) (zero, 200, 300, and 400 mg/l) and Carbaryl (zero, 700, 1200, and 1700 mg/l) at 40 days after full bloom stage during onyear. At the end, yield, fruit characteristics including fruit weight, fruit length and diameter and their ratio, total soluble solids, vitamin C, total acidity and TSS/TA ratio were measured. Analysis of variance was performed by ANOVA procedures (SAS 9.1 for Windows) and significant differences were calculated according to Duncan’s multiple range tests (P < 0.05). Results and discussion: according to the results, yield and fruit weight were significantly affected by the interaction of type of fertilizer × time of foliar application, while fruit length and diameter were not significantly affected by them. Also, fruit length and diameter were affected significantly by fertilizer type. Foliar application of urea (0.3%) + Magnesium sulphate (0.1%) in the early of February at oncrop year significantly increased the yield of Kinnow mandarin trees in offyear. It highlights the role of time of foliar application and ratio of nutrients on adjustment of alternative bearing of Kinnow mandarin in a special region. Results shows, total acidity of fruits was significantly affected by time of foliar application while other chemical properties of fruits were not significantly affected by time of foliar application, type of fertilizers and their interaction. The results indicated, the effects of foliar application of NAA and Carbaryl at 40 days after full bloom stage in onyear on yield and fruit length were significant while fruit weight and diameter and the ratio of fruit length to diameter were no significantly affected by these compounds. The highest and lowest yield of kinnow mandarin trees was related to the treatments of control and foliar application of NAA (400 mg/l), respectively. Regarding to the yield of Kinow mandarin trees, there were no statically significant difference between foliar application of Carbaryl and control treatment. Conclusion: Overall, the highest yield of trees in offcrop year was related to the treatment of foliar application of urea (0.3%) + Magnesium sulphate (0.1%) in the early of February (oncrop year) that had significant difference with control trees and it was able to adjust alternative bearing to a satisfactory level. Based on the results, Carbaryl compound is not able to adjust alternative bearing of Kinnow mandarin trees at 40 days after full bloom stage in Dezful region. Among different concentration of NAA, NAA spraying with concentration of 200 mg/l adjust alternative bearing more appropriately and had significant difference with control trees, but the concentration of 300 and 400 mg/l NAA reduced the level of yield with a great intensity, which is not recommended.