Protective Effects of Green 50% Net Shading and Salicylic Acid on Vegetative Growth, Flowering and Fruit Attributes of Apricot

Document Type : Full Paper

Authors

• Ali Akbari
• Reza Fatahi
• Zabihollah Zamani
• Ali Ebadi

Department of Horticultural Science, Faculty of Agriculturalt, University of Tehran, karaj, Iran.

Abstract

Keywords

• Heat stress
• protected fruit production
• photosynthetic system function

Main Subjects

• Fruit Science

Extended Abstract

Introduction

Climate change and global warming are the major concerns of the current century. According to previous reports, the world is warming up about 0.2 °C per decade. This increasing in air temperature can cause heat stress in fruit trees in terms of heat stress injury in the summer and unsatisfying bud dormancy during the warm winter. Managing strategies for this tragedy include using protected cultivation such as net shading and foliar spraying of salicylic acid will be helpful to protect trees against summer heat stress.

Materials and Methods

Net shading and salicylic acid treatments were applied on trees of three apricot cultivars and performed as a Randomized Complete Block Design. Foliar application of salicylic acid in concentration of 0.00 (control) and 0.1 mM was applied three times with appropriate intervals on apricot trees. Some attributes related to vegetative growth and fruits such as recurrent shoot growth, flower density, flowers and fruit set percentage, fruit quality (TA, TSS, color, harvesting time), as well as the relative water content of the leaf,  photosynthetic pigments and chlorophyll fluorescence were evaluated.

Results and Discussion

The time of ripening under shading net showed a 10 days delay with less colored fruits especially in late ripening cultivars. Net shading time depends on cultivars and is recommended when fruits were harvested or near to harvest stage. Applying green net (50%) on apricot trees reduced leaf temperature by an average of 4.5°C. Shading was able to increase current growth of branches and induction of flowers in the apricot trees. The yield and quality of apricot fruits were affected by cultivar under the net shading. The shading reduced evaporation and improved the water status of apricot tree leaves. This will help water relationship of trees under hot summer when water is not available sufficiently. It may also help to save water resources or running regulated deficit irrigation (RDI) system. Net shading also increased the membrane stability index and the photosynthetic systems function, which improves leaf gas exchange. This result showed that net shading was able to protect apricot trees against heat stress during the summer. Foliar application of salicylic acid in three consecutive times at a concentration of 0.1 mM on the apricot tree increased flower buds and next year's yield. Salicylic acid increased the relative leaf water content and photosynthetic system function.

Conclusion

 In general, the results showed that net shading and salicylic acid made apricot trees more tolerant to summer heat stress. The time of applying net shading is important and cultivar-dependent. The main factor that requires consideration is fruit harvesting time. Early shading will reduce fruit color and other fruit quality attributes.