Document Type : Full Paper

Authors

• Saiyed Mohammad Mahdi Mirfatah ¹
• Mousa Rasouli ²
• Mansour Gholami ³
• Abbas Mirzakhani ⁴

¹ Department of Grape and Raisin Research Institute, Malayer University, Malayer, Iran

² Department of Horticultural Science Engineering, Faculty of Agriculture and Natural Resources, Imam Khomeini International University, Qazvin, Iran

³ Department University College of Omran-Toseeh, Hamedan, Iran

⁴ Department of agricultural and horticultural department, Center for Agricultural Research, Education and Natural Resources of Arak Province, Agricultural Research, Education and Extension Organization, Arak, Iran

Abstract

Keywords

• Drought stress
• Grape
• Proline
• Scion and Rootstock

Main Subjects

• Fruit Science

Extended Abstract

Introduction

     Abiotic stresses are of the upmost factors limiting plant production in the world. As an economically important crop, grape can be considered as a model of perennial plant to study plants tolerance to drought stress. In recent years, different regions in the world, such as the Mediterranean regions of Europe, Southwest Asia, and North America, are allocated to grape cultivation. These regions are generally suffered from drought stress, especially at grape flowering and fruit setting, consequently resulted in a reduction in its yield and fruit quality. Climate change and water stress have increased the number of hot and dry periods in the world, and this condition needs to be regarded when establishing a new vineyard. In general, grape is a commercial fruit with high economic importance, but remarkably affected by abiotic stresses such as drought stress. Therefore, grafting has been widely used in agriculture to increase plants tolerance to abiotic stresses, in a way that it contributes to breeding programs for selecting drought-tolerant plants through selecting and integrating morphological and physiological traits. In addition to employing methods active in reducing drought, using drought-tolerant cultivars as suitable rootstocks is an appropriate way to alleviate the adversary effect of drought on plants. The tolerance of grape rootstock to drought is different based on the type of variety. A suitable combination of rootstock and scion may improve grape yield under water stress.

Materials and Methods

In order to investigate the effect of drought stress on the morphological, physiological, and biochemical traits of seven grafted rootstocks, an experiment was conducted in a split-plot design based on a randomized complete block (RCBD) with three replications, during 2018-2021. Rootstocks ('Bidaneh Ghermez', 'Bidaneh Sefid', 'Rashe', ‘Sahani', 'Kare Royeh', 'Moulai' and 'Chafte' cultivars) were obtained from orchard collections in Qazvin, Kordestan and Malayer universities and planted in an orchard located at the Agricultural Research Station of the Center for Research and Education of Markazi Province in March 2018. On the following year, scions of 'Bidaneh Ghermez' were grafted on all seven rootstocks. Grafted plants, at 5-6-leaf stage, were subjected to three levels of drought, including field capacity (FC) (as control), 75% moisture (as moderate stress), and 55% moisture (as severe stress). The studied traits were leaf number, branch length, leaf area, wet and dry leaf weight, stomatal density, electrolyte leakage, cell membrane stability, relative water content (RWC), chlorophyll, carotenoid, proline, soluble carbohydrate, malondialdehyde (MDA) and catalase, which were measured in plants exposed to drought stress condition for two months.

Results and Discussion

Our findings showed that the interaction effect of drought stress × cultivar was significant in terms of leaf surface traits, soluble carbohydrates, proline, total chlorophyll, carotenoid, catalase, RWC, and MDA (p<0.01). Furthermore, the main effect of drought stress had a significant effect on leaf number, branch length, leaf fresh weight, stomatal density, electrolyte leakage and cell membrane stability. The result of the mean comparison showed that the severe drought increased the amount of proline and catalase in the treated plants, but reduced total chlorophyll content and cell membrane stability. In general, the 'Bidaneh Ghermez' cultivar (as scion), grafted on 'Chafte', 'Moulai' and 'Kare Royeh' cultivars (as rootstocks), provided a higher potential to tolerate drought stress, as compared to other scion-rootstock combination examined in this experiment. In addition, our findings revealed that drought not only decreased photosynthetic pigments and conversely increased cell membrane electrolyte leakage, but also higher content of proline and MDA as well as antioxidant activities. Moreover, the results showed that raising drought level led to a reduction in the plant growth parameters and shoot morphology characteristics. In this research, some cultivars, such as 'Chafte', 'Moulai' and 'Kare Royeh', accumulated lower MDA rather than other cultivars, indicating their tolerance to drought stress. In our research, treated cultivars were found to have more ion leakage in comparison to the control, especially at severe drought stress. At moderate and severe levels of drought stress, the amount of ionic leakage in 'Bidaneh Ghermez', grafted on the rootstocks of 'Kare Royeh', 'Bidaneh Sefid' and 'Chafte', was lower than that in the remaining rootstocks. Besides, the results showed that the three above-mentioned rootstocks were tolerant to drought because of higher proline content and lower chlorophyll loss, as compared to the other studied rootstocks. Furthermore, the highest chlorophyll content was found in 'Bidaneh Ghermez' grafted on 'Kare Royeh' and 'Chafte' at high level of drought stress. In general, under drought stress, 'Chafte' and 'Kar Royeh' also had lower chlorophyll loss, as compared to the other rootstocks.

Conclusion
An increase in some characteristics of treated cultivars could implicate their tolerance to drought stress. Although the photosynthetic characteristics of plants generally decline due to drought stress, a reduction in these characteristics was not observed remarkably in 'Chafte', 'Moulai' and 'Kare Royeh' cultivars, as compared to other rootstocks, representing their tolerance to drought. Therefore, they may be suggested as drought tolerance rootstocks when using 'Bidaneh Germez' as scion in specific regions of Markazi province that are susceptible to water scarcity.