Electronic Journal of Polish Agricultural Universities (EJPAU) founded by all Polish Agriculture Universities presents original papers and review articles relevant to all aspects of agricultural sciences. It is target for persons working both in science and industry,regulatory agencies or teaching in agricultural sector. Covered by IFIS Publishing (Food Science and Technology Abstracts), ELSEVIER Science - Food Science and Technology Program, CAS USA (Chemical Abstracts), CABI Publishing UK and ALPSP (Association of Learned and Professional Society Publisher - full membership). Presented in the Master List of Thomson ISI.
Volume 19
Issue 1
Available Online: http://www.ejpau.media.pl/volume19/issue1/art-01.html


Hossein Sajadian
Department of Agriculture Science, Payame Noor University, Iran



In Iran, pistachio is affected by fruit Endocarp Lesion disorder, which occurs as a result of calcium deficiency. To investigate the effects of different calcium treatments on this disorder and some nut characteristics in Pistacia vera cv. Akbari, an experiment was conducted using completely randomized design with five treatments in three replications on 20-year-old trees in Rafsanjan. The treatments included T1 – control treatment, T2 – calcium sulfate (gypsum), T3 – calcium sulfate and calcium chelate foliar spray, T4 – calcium sulfate and calcium nitrate and T5 – calcium sulfate, calcium nitrate and calcium chelate foliar spray. The results showed that different calcium treatments had a significant effect on the percentage of undamaged fruits and damaged fruits by the disorder. The highest and lowest percentage of undamaged and damaged fruits was observed in T5. In evaluating nut characteristics, the highest percentage of splitting nuts, the least percentage of non-splitting nuts and immature nuts, and the least number of grains per one ounce were obtained in T5. In measuring leaf nutrient contents, the least amount of Mg, the highest amount of Ca and the highest ratio of Ca/Mg in leaves were observed in T5. The high ratio of Ca/Mg reduced Mg poisoning and also the Endocarp Lesion. As shown in the results, application of calcium sulfate (gypsum), calcium nitrate and calcium chelate foliar spray (T5) can be more favorable than other treatments, in reducing Endocarp Lesion disorder and improving nut characteristics in Pistacia vera cv. Akbari.

Key words: Pistachio, endocarp lesion disorder, calcium, nut characteristics.


Pistachio is one of the horticulture crops in Iran and one of the most important non -oil exports [23]. One of the identified disorders in pistachio is nut Endocarp Lesion disorder which continues in fruit development stages, from the beginning of the endocarp formation to complete hardening of endocarp and fruit ripening; it makes fruit to remain soft and not firm. This disorder has spread in Iran, especially in Kerman province, the main pistachio growing area of the world and has caused decrease and severe damage of crop in different cultivars of pistachio, such as Akbari commercial cultivar [10]. This disorder has also been observed in Kerman and Trabonella cultivars in pistachio growing areas in USA (California), and it has been called Stylar End Lesion. In relation to the disorder causative agents, it has been said that the observed symptoms are not connected with any pest [29]. Also, according to studies, different species of bugs, other pistachio pests and plant pathogens do not play a role in developing the disorder. Symptoms and damage manner of climate factors on pistachio fruit is completely different from the disorder [10]. According to the studies of Mahmoudimeimand [17], Endocarp Lesion exists due to calcium deficiency, and inadequate calcium to magnesium ratio causes lack of calcium absorption by the plant. Researchers, by examining the role of macro- and micro-elements on the mentioned disorder, also showed that other elements, except calcium and magnesium, do not have a role in this disorder [10]. Calcium is one of the most important mineral elements which is effective in fruit quality and shelf life. This element exists in the structure of the cell’s middle lamella in a compound that is called calcium pectate, and until its amount is sufficient, it cannot prevent pectin wall demolition [18]. Studies have also shown that it protect cell membranes against damage caused by various stresses; presence of calcium in the external environment is essential [22]. Fruits with a little calcium have respiration rate higher than other fruits; therefore, they decay faster. For delay in fruit decay, it is necessary to accelerate and strengthen calcium absorption and its transfer to fruit in ways. First, this action was performed in the form of foliar application in crops such as apple, pear and strawberry and showed satisfactory results [15, 18, 30]. Calcium deficiency in different crops such as tomato and apple causes different symptoms and it causes Blossom-End Rot in tomato [14]. Applying CaCl2 increased the firmness and the shelf life of tomato fruits [31]. In apple fruits, this element deficiency appears in the form of brown spots which is called Bitter Pit [25]. Ca foliar application on apple decreased this disorder and improved the fruit firmness, its quality and shelf life [8]; also calcium chloride (CaCl2) spray decreased the incidence of brown rot during storage [13]. In pear, Ca foliar application decreased postharvest decay and cork spot [27, 28]. Pre-harvest Ca applications in peach significantly reduced the number of brown rot infected fruit [9]. Foliar sprays of CaCl2 at the pea and veraison stages of berry development in grapes, improved the berry firmness, shelf life and fruit quality [19], whereas Ca application after veraison was less effective in improving berry Ca concentration and fruit quality during storage [5]. Calcium nitrate foliar spray in the early stages of Mandarin fruit cellular growth decreased the percentage of cracked fruits significantly [1, 21]. Ca content of papaya fruit was significantly increased by pre-harvest calcium sprays and anthracnose incidence of fruits reduced too [16]. In pistachio cv. Kalleghouchi, CaCl2 foliar application decreased Endocarp Lesion disorder [10].

Regarding other presented reports in relation to the positive effects of calcium foliar application on different plants, this experiment was conducted to investigate the effect of different calcium sources on Endocarp Lesion disorder and also some nut characteristics in Pistacia vera cv. Akbari.


Different calcium treatments on Endocarp Lesion disorder were compared and some nut characteristics were shown in Pistacia vera cv. Akbari damaged as a result of the mentioned disorder in Rafsanjan, which is one of the most important pistachio growing areas in Iran. The geographical coordinates of Rafsanjan are 30° 24' 24" North, 55° 59' 38" East and it has semi arid climate. The experimental orchard included 20-year-old trees. The experiment was conducted with five treatments of calcium, including: T1 – control treatment, T2 – calcium sulfate (gypsum), T3 – calcium sulfate and calcium chelate foliar spray, T4 – calcium sulfate and calcium nitrate and T5 – calcium sulfate, calcium nitrate and calcium chelate foliar spray in completely randomized design. Each treatment was applied on three rows of trees (40 trees in each row) and in three replications. First gypsum (40 ton/ha) was added to the soil in the form of a strip with a width of 1.5 m from both sides of the trees and then heavy irrigation was done in March. In T4 and T5, calcium nitrate (75 kg/ha) was added to the soil in April. In T3 and T5, calcium chelate foliar spray (15% concentration) was done at the beginning of the rapid growth of endocarp in early May at 7 to 9 a.m. To evaluate the Endocarp Lesion disorder and the effect of treatments on contamination rate, the undamaged and damaged fruits were counted with a sampling by 20 pistachio clusters of 10 trees randomly for each treatment and in three replications in mid-June. To investigate some nut characteristics, the number of splitting nuts, non-splitting nuts, blank nuts, immature nuts and the numbers of grains per one ounce were counted by gleaning 30 clusters of 10 pistachio trees randomly for each treatment and in three replications at harvest. To determine the leaf nutrient contents including Ca, Mg, Na and Ca/Mg, leaf analysis was done in Soil Analysis Laboratory of Pistachio Research Institute, Iran. Sampling of leaves was done in late July; plant extract was prepared with dry ash method. For this purpose, after washing leaf samples and drying them in air, they were grounded and placed in oven at 70°C for 24 h. Then, 1 g of each sample was weighed and burnt in electric furnace at 550°C for 5 h to change it to white ash. When the samples were cooled at 10cc, HCl 3 normal was added to each sample and reached volume of 100 mm with distilled water. In the obtained extract, Na was measured with Flame Photometer (Model: PFP7), and Ca and Mg with Atomic Absorption Spectrometer (Model: GBC 932). Ca/Mg was obtained by the ratio of Ca to Mg. Data were analyzed with SAS 9.1 Software and means were compared with Tukey test at 5% level.


In this research, according to the analysis of variance (ANOVA), the percentages of undamaged and damaged fruits were significant at 1% level (Tab. 1). The comparison of the means showed that the highest percentage of undamaged fruits was in the calcium sulfate, calcium nitrate and calcium chelate foliar spray treatment (T5) and in T4, T3, T2 and T1, the percentage reduced respectively (Fig. 1). Also, the least percentage of damaged fruits was in T5 and the highest percentage was in T1 (Fig. 1). The analysis of variance for some nut characteristics including the percentage of splitting nuts, non-splitting nuts, immature nuts and the number of grains per one ounce were significant at 1% level but the percentage of blank nuts was not significant (Tab. 1). Comparison of the means showed that the highest percentage of splitting nuts was obtained in T5 and the least percentage was in T1. The lowest percentage of non-splitting nuts, immature nuts and the number of grains per one ounce were observed in T5 and increased in T4, T3, T2 and T1, respectively (Fig. 1). According to the analysis of variance for leaf nutrient contents, the amounts of Mg and Ca/Mg were significant at 1% level and Ca at 5% level but the amount of Na was not significant (Tab. 2). In the comparison of the means, the least amount of Mg and the highest amounts of Ca and Ca/Mg were observed in T5 (Fig. 2).

Table 1. Analysis of variance for nut characteristics
Mean Square
undamaged fruits
damaged fruits
splitting  nuts
non-splitting nuts
immature nuts
blank nuts
5.52 ns
ns,* and**: non significant, significant at 5 and 1% probability levels, respectively.

Fig. 1. The effects of different calcium treatments on the nut characteristics

Table 2. Analysis of variance for leaf nutrient contents
Mean Square
ns,* and**: non significant, significant at 5 and 1% probability levels, respectively.

Fig. 2. The effects of different calcium treatments on the leaf nutrient contents

The most important role of calcium in fruits is the strengthening of the cell wall. Microscopic observation has shown that at the time of fruit ripening, disorganization of cells in fruit with high calcium occurs later than fruits with low calcium [3]. The strength of pistachio fruit endocarp at the time of formation depends heavily on the availability of calcium ions. Calcium absorption by the roots of the pistachio tree is disabled; it means the amount of transpiration defines the amount of absorption and causes calcium ion movement in the xylems towards the organ that needs calcium [17]. The results of this experiment showed that the application of different calcium treatments decreased the disorder than the control treatment and the combined use of calcium sulfate, calcium nitrate and calcium chelate foliar spray had more favorable effects on reducing the disorder. Hashemirad and Heidarinejad [10] showed that CaCl2 foliar application on pistachio trees cv. Kalleghouchi in mid-April decreased the contamination rate. In grapes, spraying CaCl2 twice or three times before veraison increased the Ca concentration of grape berries and improved flesh firmness and berry breaking force [5]. Application of CaCl2 spray on peach increased mesocarp Ca concentration only in June, during the pit-hardening period. The Ca application did not increase mesocarp Ca concentration at harvest, but decreased internal browning after two weeks of cold storage [32]. Mirzaei et al. [20] reported that Endocarp Lesion disorder probably occurred because of indisposition of Ca to Mg ratio as a result of more increase of Mg in irrigation water in pistachio gardens, therefore, increase of Mg caused false deficiency of calcium in fruit. The authors explained that the best ratio of Ca to Mg is when the ratio is more than two, and when this ratio is less than one magnesium poisoning occurs. Based on the results of this experiment, the best ratio of calcium to magnesium (2/1) was obtained in the treatment of calcium sulfate, calcium nitrate and calcium chelate foliar spray (T5). The results of the present study are in accordance with results of Mahmoudimeimand [17] which showed that adding gypsum to the pistachio gardens can be useful in correcting Ca/Mg in favor of Ca, and it can decrease the disorder rate. Application of gypsum in the pistachio gardens in addition to decrease in the disorder rate causes increase in the penetration of water and soil moisture storage, increase in irrigation water efficiency, improvement in soil structure, decrease in sodium soil pH, etc. Ca which is released by the dissolution of gypsum in the soil solution is one of the main components of the biochemical mechanisms which play a role in the absorption of nutrients by the roots of tree. In the absence of enough calcium in the root of trees, these absorption mechanisms are disrupted [17]. Also, calcium can improve soil and moderate the effects of salinity [2, 7, 11]. In this experiment, after applying the different treatments of calcium, the percentage of splitting nuts was increased; the percentage of non-splitting nuts, immature nuts and the number of grains per one ounce were decreased; therefore, nut characteristics were improved. Calcium sulfate, calcium nitrate and calcium chelate foliar spray treatment (T5) had the best effect. Increase in the percentage of splitting can be due to increase in the calcium concentration and its role in the cell membrane and walls. In accordance with the results of the present study, Davarinejad et al. [6] reported that in pistachio cv. Ohadi, the highest percentage of splitting was obtained by Ca foliar application. In red apples, Ca foliar application enhanced the red skin color, juiciness, texture and firmness of fruit [26]. Plum fruits cv. Stanley treated with Ca in early stage of growth were larger and lost their water later [24]. It is reported that the use of Ca for the development of strawberry fruit wall and its high yield is needed [4]. Ca treatment on strawberry increased the strength and firmness of the fruit and its shelf life [12].


According to the obtained results, the application of gypsum as a calcium source and soil corrector, calcium nitrate soil application and calcium chelate foliar spray had considerable effects on improvement of this disorder and reduced fruit drop . Also, using calcium sulfate, calcium nitrate and calcium chelate foliar spray (T5) had more favorable effect than other treatments in reducing Endocarp Lesion disorder and improving nut quality and quantity in Pistacia vera cv. Akbari.


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Accepted for print: 31.12.2015

Hossein Sajadian
Department of Agriculture Science, Payame Noor University, Iran

email: hssajadian@yahoo.com

Responses to this article, comments are invited and should be submitted within three months of the publication of the article. If accepted for publication, they will be published in the chapter headed 'Discussions' and hyperlinked to the article.