مجله تولید و فرآوری محصولات زراعی و باغی
سال هشتم شماره 4 (زمستان 1397)

The successive droughts and the degradation of water and soil resources quality (salinity and toxicity of nutrients like boron) are serious challenges for tropical fruit tree cultivation such as mango in Hormozgan province south of Iran. Using some nutrients like silicon is believed to be effective in order to mitigate the aforementioned problem. Hence, an experiment was carried out in which six boron levels (0, 5, 10, 20, 40 and 80 mg B/kg soil as H3BO3) and four levels of silicon (0, 70, 140 and 280 mg Si/kg soil as Na2Si3O7) were applied on young mango seedlings. The results showed that the use of boron (80 mg B/kg soil) had a significant effect on measured mango vegetative traits; as the dry weights of leaf, stem and root were reduced by 66, 57.4 and 58.8 percent, respectively. Moreover, the chlorophyll index was decreased by boron application whereas using Silicon increased the chlorophyll index. Using silicon, in all boron levels increased proline and decreased reducing sugars concentrations in the mango plant.

The effect of foliar application of zinc sulfate and seaweed on qualitative and quantitative characteristics of local Kermanshah cantaloupe (Cucumis melo L., Cantalupensis Group) cv. Kalak was investigated. After sowing seeds in the field, the plants were sprayed in three stages including the 4-6 leaf stage, flowering and after the fruit set. The experiment had a factorial design based on the randomized complete block design with 9 treatments including various concentrations of zinc sulfate (0.5 and 1 g L-1) and seaweed (0.5 and 1 g L-1) and was repeated three times. The results of analysis of variance showed that zinc sulfate at 0.5 g L-1 and seaweed at 1 g L-1 had significant effects on the weight, length and diameter of the fruit, the weight of the fresh fruit, fresh and dry weight of the plant, and fruit firmness. The highest amount of vitamin C was observed in zinc sulfate at 1 g L-1 and seaweed at 0.5 g L-1. The highest total seed weight was obtained in zinc sulfate at 0.5 g L-1 and seaweed at 1 g L-1. Foliar application of zinc sulfate and seaweed did not have a significant effect on total soluble solids (TSS). However, zinc sulfate at 0.5 g L-1 increased the amount of titratable acid (TA) in the fruit juice. The highest amount of the TSS/TA ratio of the fruits was observed in application of seaweed at 1 g L-1. Overall, the findings of the present study indicated that simultaneous application of zinc sulfate and low concentrations of seaweed extract has a significant effect on many qualitative and quantitative characteristics of “Kalak” Cantaloupe and can be recommended as a biofertilizer.

In order to evaluate the suitability of maize hybrids in different planting dates, an experiment was conducted as split plot in JalilAbad, Varamin, Iran in 2015. Main and sub plots were planting date (D1: April 4, D2: April 19, D3: May 5, D4: May 20) and maize hybrids (H1: Gazda, H2: Maxima, H3: KSC 701, H4: AS160) respectively. Results indicated that there was variation between hybrids in terms of leaf area index (LAI), dry matter, crop growth rate (CGR), relative growth rate (RGR) and net assimilation rate (NAR) in different planting dates. Also results showed that the effects of planting date, hybrid and planting date × hybrid interaction on plant height, plant weight, ear weight, ear/plant weight ratio, silage yield and water use efficiency were significant. Among the qualitative traits examined, the effects of hybrid on protein and neutral detergent soluble fiber were significant. The best planting date for achieving the highest silage yield of hybrids Maxima and AS160 were May 5 and 20, but for KSC 701 was April 19 and May 5. However hybrid Gazda had a similar yield in all planting dates. It was concluded that even though cultivation of KSC701 and Maxima seems preferable in terms of silage yield but repeating this experiment in further years is necessary for a solid recommendation.

Terminal heat stress in hot and dry conditions like Ahwaz reduces the quantitative and qualitative yield of wheat. In order to study the effect of terminal heat stress on grain filling period duration, grain filling rate and quantitative and qualitative yield of 20 spring bread wheat cultivars, a field experiment was conducted in Research Farm of Agricultural Sciences and Natural Resources University of Khuzestan, Iran in 2008-2009 as stripe block design and included four sowing dates (6 Nov., 6 Dec., 5 Jan. and 4 Feb.) in horizontal plots and 20 spring bread wheat cultivars in vertical plots with three replications. The analysis of variance showed that sowing date, genotypes and their interaction had a significant effect on measured traits. The mean comparison of interaction effect showed that in sowing date of 6 Dec. the highest grain yield (7254 kg/ha) was related to Chamran cultivar and the lowest grain yield (5445 kg/ha) belonged to Maroon cultivar. In terminal heat stress condition (sowing date of 4 Feb.), the highest grain yield (2323 kg/ha) was related to Maroon cultivar and the lowest grain yield (1258 kg/ha) belonged to Hamoon cultivar. Generally, in early (6 Nov.), timely (6 Dec.) and late (5 Jan) seeding, Chamran cultivar was suitable and in very late (4 Feb.) sowing, cultivars of Maroon, Virinak, Arvand and Atrak were suitable.

Drought occurrence is one of the most important reasons for reduced yield in crops. At least in arid and semi-arid areas an efficient approach to tackle this problem is to identify and grow tolerant genotypes with the help of drought tolerance indices. The main objective of this research was to study the effects of drought on the performance of six genotypes of lentil in order to evaluate some of the drought tolerance and sensitivity indices, including stress tolerance index (TOL), stress susceptibility index (SSI), mean arithmetic (MP), geometric productivity of productivity (GMP), harmonic mean (HAM), yield stability index(YSI) and stress tolerance index (STI) in two conditions of drought stress (Non-irrigation) and normal conditions (irrigation). The experiment was conducted as a split plot based on randomized complete block design with three replications and six genotypes in Research Farm of Payame Noor University Center of Asadabad, Hamedan-Iran in 2017. Data obtained from growing genotypes under normal and drought conditions were used to calculate drought tolerance indices. There was a significant difference between genotypes in terms of response to late drought, most of the studied indices were able to discriminate susceptible and tolerant genotypes. Based on the examined indices, Bile Savar and Gachsaran genotypes were recognized as tolerant genotypes. The distribution of genotypes in the biplot space revealed a genetic variation between them in relation to drought stress and based on this, Bile Savar and Ghachsaran genotypes were recognized as drought tolerant and high yielding. Also, according to the results of the main components analysis, the first and second components described 100 percent of variation among the genotypes for the examined drought tolerance indices.

Petunia (Petunia hybrida) is an ornamental plant species of high economic potential. One of the appropriate methods for propagation and breeding of petunia is tissue culture. This experiment was conducted to investigate the effects of different concentrations of benzyl adenine (BA) either alone or in combination with different concentrations of naphthalene acetic acid (NAA) on the regeneration of adventitious shoots and callus production in Petunia hybrida. For the regeneration of adventitious shoots and callus production, leaf segment explants taken from germinated seeds were cultured on MS basal media supplemented with different concentrations of BA (0.1, 0.4, 0.8 mg L-1) solely and/or in combinations with and NAA (0, 0.1, 0.2 and 0.4 mg L-1). Cultures were incubated under dark conditions for two weeks and then transferred to light condition. After 20 days of keeping in the light condition, the results showed that BA and NAA had significant effect on shoot regeneration. When BA applied alone, the lowered concentrations were effective in shoot regeneration, however when used in combination with NAA, its increased concentrations were more suitable. The greatest percentage of shoot regeneration was recorded in the medium with high level of BA to NAA. The highest number and fresh weight of shoots (18 shoots per explant) were obtained in MS medium supplemented with 2 mg L-1 BA + 0.4 mg L-1 NAA. The greatest shoot length (5.1 cm) was obtained in MS medium containing 0.5 mg L-1 BA + 0.2 mg L-1 NAA. Also, the greatest callus fresh weight was observed in MS medium supplemented with 0.5 mg L-1 BA + 0.4 mg L-1 NAA. Therefore, MS medium supplemented with 2 mg L-1 BA combined with 0.4 mg L-1 NAA could be suggested for direct shoot regeneration and large scale propagation of petunia from leaf explants.

Water stress is the most important abiotic stress in crop production. Silicium (Si) is the second most abundant element in the soil with beneficial effects on plant tolerance to biotic and abiotic stresses. In order to evaluate the effect of this element in increasing tolerance to water deficit in wheat, a factorial experiment was conducted based on a completely randomized design with three replications in the greenhouse of College of Agriculture, Shiraz University, Shiraz, Iran. Treatments included four wheat cultivars, Shiraz, Sirvan, Ofogh, Baharan, foliar silicon application in two-levels, zero (control), and 3 mM, and three levels of water deficit (field capacity, 40% and 60% of field capacity). The results showed that water deficit reduced spike length (31%), dry matter per plant (41%), grain yield (25%), greenness index (11%), flag leaf relative water content (24%), catalase (24%), peroxidase (70%) and superoxide dismutase activity (41%). Baharan and Sirvan cultivars were superior for greenness index and peroxidase activity. However, foliar silicon application at 3 mM concentration ameliorated the negative impacts of water deficit stress. Foliar application of silicon enhanced all the above parameters including antioxidants. For a majority of the measured characteristics, it was evident that Baharan and Sirvan, as water deficit tolerant cultivars, and Ofogh, were superior compared to Shiraz cultivar. The results showed that foliar application of silicon increased the activity of antioxidant enzymes and as a result ameliorated the negative impacts of water stress.

In order to study the physiological growth indices and yield of green bean in response to vermicompost amendment under drought stress conditions a field experiment was conducted in Dezful, southwest of Iran during 2016 using a split plot design in a randomized complete block design with four replications. Application of drought stress by irrigation interval method at four levels of irrigation (irrigation after 100, 140, 180 and 220 mm evaporation from class A evaporation pan) as the main factor and 0, 4, 8 and 12 tons ha-1 of vermicompost were considered as a sub factor. With intensifying drought stress from 140 to 220 mm evaporation from the evaporation pan, maximum values of dry matter of the plant, leaf area index, plant growth rate and durability of the leaf area significantly decreased. Except for the relative growth rate which was less affected by vermicompost, increasing the application of vermicompost from 4 to 12 tons ha-1 caused a great increase in the remaining physiological growth indices compared to control treatment. Interaction of drought stress and vermicompost on all traits was not significant except for green pod yield. The vermicompost – related increase in yield of green bean in drought stress conditions (21%) was higher than the increase in favorable conditions (16%). The highest and lowest correlations with yield were related to dry matter of the plant (r=0.97**) and relative growth rate (r=-0.27). In general, the results showed that vermicompost application under stress and non-stress conditions improved the physiological growth indices and hence the yield of the green pod and could be recommended for green bean production in the area.

In this research, CERES-Maize crop model was calibrated, validated and evaluated for different maize hybrids under climatic conditions of Gonabad, east of Iran. For this purpose, an experiment was carried out based on a split-split plot randomized complete blocks design. Main factor consisted of three irrigation regimes (optimum irrigation, moderate drought stress, and severe drought stress), subplot factor included of four levels of nitrogen fertilizer (0, 120, 180, and 240 kg/ha) and sub-subplot factor consisted of three maize varieties (DC 370, ZP 677, and SC 704). CERES-Maize model simulated maximum leaf area index of maize varieties with high precision. However, in most of situations predicted values underestimated as compared with actual values. In addition, the model predicted kernel yield and biological yield of three mentioned maize varieties, reasonably. Variations of kernel nitrogen yield of maize varieties under different water and nitrogen regimes were simulated very well by the model. Although, in most of treatments model data values were lower than measured data from field experiment. Model simulated the increases of water use efficiency due to decrease of water supply and increase of nitrogen application, reasonably. Yet, the model accuracy for prediction of water use efficiency of maize with increase of drought stress level was slightly decreased and deviation of the two data sets was increased. According to the results of this research, the CERES-Maize model could be suggested for decision making in maize production for climatic regions similar to location of this experiment.

In order to optimize direct regeneration of potato cultivars (Solanum tuberosum L.) including Arinda, Agria, Sante, Maradona and Marfona, a factorial experiment was carried out in the form of completely randomized design with three replications. Internode explants were placed on MS medium supplemented with different concentrations of 6-Benzylaminopurine (1, 2, 5, 10 and 15 mg/l) in combination with Kinetin (0.5, 1, 2, 5, 10 and 15 mg/l). Results showed that using 6-Benzylaminopurine (BAP) was more effective than Kinetin in direct regeneration of potato. Low concentrations of BAP had the greatest effect on regeneration and also length of root and shoot but maximum numbers of somatic embryos were obtained in the presence of high a concentration of BAP. Using kinetin only influenced the number and length of regenerated shoots. Although Kinetin had no effect on the rate of regeneration but BAP increased it. There were significant differences among cultivars in all traits. Among tested cultivars, Marfona had the best direct regeneration ability in vitro condition. Therefore, it can be concluded that induction of direct organogenesis in potato is largely dependent on the genotype, and the use of BAP growth regulator plays an important role in inducing direct regeneration in potato cultivars.