نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه علوم باغبانی،دانشکده کشاورزی، دانشگاه شیراز، شیراز، ایران
2 گروه علوم باغبانی، دانشکده کشاورزی، دانشگاه شیراز، شیراز ، ایران
3 گروه علوم باغبانی، دانشکده کشاورزی، دانشگاه گیلان،رشت، ایران
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Global warming and recent droughts are one of the main factors in reducing agricultural products. This research was conducted in order to increase the adaptability of ‘Asgari’ grapevine against drought stress in rainfed conditions. In this research, foliar spraying with kaolin (6%) and potassium sources (1.5% and 3% each of potassium nitrate, potassium sulfate and potassium chloride) was done during two seasons on 30-year-old vines located in Shiraz. Kaolin is a highly durable antiperspirant for vineyards, and it is a realistic and attractive strategy to protect grape clusters from excessive heat and sunburn. The results showed that the application of different sources of potassium caused an increase in berry weight, fruit cluster length, soluble solids, chlorophyll, leaf and fruit potassium content, relative leaf water content, and a decrease in the activity of antioxidant enzymes and leaf temperature compared to the control treatment. On the contrary, kaolin treatment decreased these traits and increased the activity of antioxidant enzymes compared to the control treatment. Potassium sources in both concentrations were able to improve the morphological and physiological characteristics of the, resulting in the greater resistance of ‘Asgari grapevine’ to drought and increase in yield compared to the control treatment. But the application of kaolin had no positive effect on studied traits, which may have been due to the inappropriate concentration used in this study.
کلیدواژه‌ها [English]
Extended Abstract
Introduction
Grape is one of the most popular small fruits, which is widely cultivated and consumed in Iran. The Fars province having the largest area under rainfed cultivation and annual production of grape, sits at the first place in the country. Changes in annual rainfall amounts and distributions cause uncertainty and high risk in rainfed cultivation and therefor decrease in rainfed crop production. The high intensity of sunlight and very high temperatures during the summer season are significant problems in many fruit growing regions of Fars province. Furthermore, drought can intensify these conditions and as a result, their adverse effects. To deal with these problems utilizing antiperspirants and improving plant nutrition, particularly with potassium, are applicable methods. As a new solution, spraying kaolin on the crowns of trees can be an effective technique for enhancing light reflection and reducing transpiration. This research was conducted in order to increase the adaptability of ‘Asgari’ grapevine against drought stress in rainfed conditions
Material and Methods
The present investigation examined the response of rainfed ‘Asgari’ grapevine to foliar application of kaolin (6%) and different sources of potassium (1.5% and 3%) over two years. The study was carried out on 30 years old grapevines grown in commercial vineyard, located in Shiraz region. Potassium nitrate (1.5% and 3%), potassium sulfate (1.5% and 3%), and potassium chloride (1.5% and 3%) were sprayed alone or combined with 6% kaolin. Four replications of 14 treatments were conducted as randomized complete blocks design, with distilled water as the control treatment. Spraying was done in two stages. The first foliar spray was applied after fruit set (June 5) and the second one shortly before the fruit color change (July 25).
Results and discussion
Results showed that different sources of potassium (Potassium Nitrate, Potassium sulfate and Potassium chloride) increased berry weight, cluster weight, total soluble solid, chlorophyll and K content of leaf and fruit compared to untreated vines and had positive effect on relative water content. Whereas, potassium application given in different sources and different doses decreased the antioxidant enzyme activities and leaf temperature compared to untreated vines. Kaolin treatment decreased berry weight, cluster weight, total soluble solid, total phenol, chlorophyll and relative water content compared to untreated vines. Kaolin treatment had negative impact on K content of leaf and fruit, whereas increased the antioxidant enzyme activities compared to untreated vines.
Conclusion
This research tried to increase the adaptation of ‘Asgari grapevine’ to rainfed condition by foliar application of potassium in two concentrations or in combination with kaolin. Potassium sources in both concentrations were able to improve the morphological and physiological characteristics of the plant compared to the control treatment. The results showed the greater resistance of ‘Asgari grapevine’ to drought and heat stress, and increase in the yield compared to the control treatment. But the application of kaolin had no positive effect on studied traits, which may have been due to the inappropriate concentration used in the study.
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