The effect of gibberellic acid, ring removal, cluster thinning and bunching on the fruit characteristics of Askari variety grapes

Dissertation for Master's Degree in Plant Production

Horticulture Orientation

Abstract

In order to investigate the effect of gibberellic acid, ring removal, cluster thinning and cluster thinning on the qualitative and quantitative characteristics of grape varieties Askari, the experiment was carried out in the form of randomized complete block design with four treatments at five different levels and in four repetitions in 2013 in Nasrabad village of Kashmar city. In this experiment, the effect of gibberellic acid in concentrations of zero, 50, 100, 150 and 200 ppm at two times of foliar spraying before flowering and after flowering, ring removal at the times of two weeks before flowering, two weeks after flowering, four weeks after flowering and six weeks after flowering, and thinning treatment at the times of two weeks after flowering, four after flowering, six weeks after flowering and eight weeks after flowering At the rate of 30% and finally, the thin cluster was examined at the same time at the rate of 5, 10, 15 and 20%. The results showed that gibberellic, ring removal, thin grain and cluster treatments increase the pH compared to the control treatment. The highest pH is related to the gibberellic treatment at a concentration of 200 ppm with an average of (3.85), while the lowest pH is related to the control treatment (3.2). Also, the highest amount of titratable acidity was related to the cluster thinning treatment with 20 clusters per vine with an average of 0.965 and the lowest amount was related to the control treatment with an average of 0.6107. The highest amount of soluble solids (TSS) was in the cluster thinning treatment with 20 clusters per vine with an average of 18.75 and the lowest in the control treatment with an average of 14.75. The results of a number of quantitatively measured factors also showed that the highest yield of the tree related to the ring removal treatment in 2 weeks after flowering with an average of 40.38 kg and the lowest yield related to the control treatment with an average of 19.78. Gibberellic treatment at a concentration of 200 ppm had the lowest yield among all treatments with an average of 2.223 kg per tree. Of course, cluster thinning treatment after ring removal treatment has also increased yield. The highest number of clusters in the ring removal treatment was two weeks before flowering with an average of 116.5 clusters and the lowest was related to the gibberellic treatment with a concentration of 200 ppm with an average of 26 clusters. Also, the highest cluster weight was related to thin cluster treatment with 20 clusters per vine with an average of 432.25 and the lowest related to gibberellic treatment at a concentration of 200 ppm with an average of 82.25, but there was no significant difference between the concentrations of 200 and 150 ppm. Gibberellic had a great effect on the length of the cluster, so that with high concentrations of 50 ppm, the length of the cluster reached 33 cm, and the lowest cluster length was recorded in the control treatment with 16 cm, also the highest number of pods was recorded in the thin cluster treatment with 20 clusters per vine with an average of 124.25 and the lowest in the gibberellic treatment at a concentration of 200 ppm with an average of 30.5.

Key words: gibberellic acid, ring removal, cluster thinning, cluster thinning, Askari grapes, soluble solids

Chapter 1

Introduction

Iran is considered one of the most important grape growing regions in the world due to its geographical and climatic conditions.

Grapes are one of the fruits that mankind has known for a long time and has used it in different ways throughout the centuries. According to the statistics of the World Food and Agriculture Organization in 2009, the area under grape cultivation in the world is 7518 thousand hectares. Among the countries of the world, Spain ranks first in terms of the area under grape cultivation, followed by Italy and France (Khoshkhoi et al., 2011).

Iran is considered one of the most important grape growing regions in the world due to its geographical and climatic conditions. Iran is the sixth producer of this product in the world.

Grapes with the scientific name Vitis spp are one of the most important fruits in the world and in Iran in terms of production.

Ignorance of the characteristics of grape varieties is one of the issues that most producers are satisfied with producing the minimum product without paying attention to them, while knowing the appropriate varieties of a region can increase the amount of the product to a great extent.

Ignorance of the characteristics of grape varieties is one of the issues that most producers are satisfied with the production of the minimum yield without paying attention to them, while knowing the appropriate varieties of a region can increase the yield to a great extent (Jalili Marandi, 1386). Different genotypes have been investigated in different weather conditions and suitable cultivars for each type of climate have been determined and recommended (Jalili Marandi, 2016).

The available commercial cultivars are randomly created as a result of the differentiation of traits caused by seed cultivation. Due to extreme heterozygosity, the results obtained from the seed cultivation of the same tree have very different traits and characteristics. The commercial grape varieties available in Iran have been created and propagated by interested gardeners at a limited level of genetic diversity. It is certain that if varieties and genotypes are investigated and identified, there is a potential to increase grape production in terms of quantitative and qualitative characteristics superior to existing varieties (Jalili Marandi, 2016).

Investigation of physiological indicators such as photosynthesis, fluorescence, chlorophyll, transpiration, stomatal conductance, stomatal resistance, leaf temperature and relative leaf water content can lead to a deeper understanding of the mechanisms related to growth, production and adaptation, and as A good criterion should be used in breeding programs to select suitable cultivars for each region (Khoshkhoi et al., 2012). If the hormone spraying is done before fertilization, i.e. 10 days before the petals fall, it will cause the destruction of the pistil and the production of seedless pods. This action is associated with the dropping of a number of pods, so in ruby ??grapes that have a dense cluster, it causes the cluster to thin out (falling of cluster flowers) and the quality of the product increases because the remaining pods have a lot of space to grow. The increase in grape yield is when hormone spraying is done after fertilization and cluster formation, which causes clusters to grow larger (Azadeh Rad, 1385). Seedless 'Beauty' variety showed the highest amount of carbohydrates and sugar among 'Thompson' and 'Gold' varieties as a result of ringing. In an experiment that was conducted on 7 cultivars with seeds and 10 seedless cultivars of 'Vinifera', one-year stem girdling stimulated sugar accumulation and ripening in most cultivars (Winkler et al., 1974). Roper et al. showed that in 'Italin Eliconia' cultivar, girdling improves fruit quality by increasing the ratio of soluble solids to acid. Ring removal in grapes accelerates maturity. In grape defoliation, by removing a complete strip from the skin of one-year-old fruiting branches (in undergrowth), using a defoliation knife at the right time, which in this study was done at the beginning of flowering, prevents the transfer of nutrients and hormones made from the leaves to other parts of the consumer for a short and temporary period, and during this period, these substances are only used to feed the bunch, which reduces the competition of young branches and other plant parts in consuming food with the bunches (Roper and colleagues, 1989).

Thinning means reducing the number of flower or fruit clusters. This action has a certain effect on increasing the quality of grapes. With gentle pruning, it means leaving a larger number of compound buds on the bush in the winter season. leaves will be more ripe and bigger. Leaving more leaves on the plant will not only provide better nutrition for the cluster, but the plant itself will also have more nutrients in general. Since thinning means cutting off some living and active parts of the plant, it has the same effect as pruning, that is, the reaction of the plant to thinning will be to concentrate more substances on the remaining parts (Mahmoodzadeh, 2008).

The effect of gibberellin on various factors such as: flower drop, growth stimulant, thinning agent, increase in cell volume, increase in length and size of pods, increase in pod weight The reduction of the number of pills has been investigated (Azadeh Rad, 2015).