نشریه روابط خاک و گیاه
پیاپی 39 (پاییز 1398)

The present investigation was carried out to evaluate the impacts of different concentrations of N and Ca and N:Ca ratio in nutrient solution on growth indices, yield and tipburn of butterhead lettuce (Lactuca sativa var. Capitata) in floating system. The experiment was conducted as completely randomized design, with 8 treatments and 3 replications, in Research Greenhouse of Shahrekord University. Treatments (different concentrations of Ca and N (mg/L) in the nutrient solution) included T1 (N60 + Ca80), T2 (N80 + Ca80), T3 (N100 + Ca80), T4 (N120 + Ca80), T5 (N120 + Ca160), T6 (N160 + Ca160), T7 (N200 + Ca160) and T8 (N240 + Ca160). Results showed that there was no significant difference between treatments for number of leaves; but significant differences were observed in tipburn percent, leaf and root fresh weight, leaf and root dry weight, and stem length and diameter. The highest head weight, length and diameter of stem, and root and leaf dry weight were observed in T1 (N60 + Ca80), T2 (N80 + Ca80) and T3 (N100+ Ca80) treatments. The weight of head in different treatments varied from 218 to 326 g/plant. Increasing the N concentration to more than 100 mg/L decreased the yield. Higher yield was obtained in 80 mg/L Ca concentration as compared to 160 mg/L. The tipburn occurrence of the treatments varied from 10.5 to 42.5 percent. The lowest tipburn occurrence was observed in T2 and T6 (N:Ca=1) treatments; while it was highest in T1 and T5 (N:Ca=0.75) treatments. Leaf analysis showed that significant difference was observed among the treatments with respect to N and Ca content. The T2 treatment (N80 + Ca80) was the best due to its high yield and lower tipburn incidence

Tomato is one of the most important horticultural crops that is corruptible and susceptible to microbial contamination. In this study, the effect of UV-C at five different irradiation intensities (0, 3, 6, 9 and 12 kJ/m2) on rot control and postharvest quality of greenhouse tomato was investigated. Tomato (cv. Newton) fruits were harvested from a commercial greenhouse at vine-ripe stage and after treatment, were stored at 10 °C and relative humidity of 85-90%. Qualitative characteristics of the fruits such as decay rate, firmness, vitamin C, total soluble solids, titratable acidity, ripening index, weight loss and color (L*, a*, b*, Hue and Chroma) were evaluated after 7, 14, 21 and 28 days of cold storage. Results showed that vitamin C, firmness and color values were decreased; while weight loss percentage and decay rate were increased during the storage period. UV-C treatments did not have significant effect on traits of color, ripening index, weight loss percentage, firmness and pH. But the fruits treated with UV-C at 6 kJ/m2 dose had low decay rate as compared to control. The highest vitamin C content was obtained in treated fruits with 12 kJ/m2 of UV-C on twenty-first day of storage. Total soluble solids and titratable acidity were decreased in high doses of UV-C treatment. According to the results, it can be concluded that UV-C treatment of tomato fruits at vine-ripe stage, at its optimal doses, can reduce fruit decay and maintain or increase its antioxidant capacity, including vitamin C.

To evaluate the commercial and local cucumber rootstocks in grafting conditions at different nitrogen (N) levels and temperatures of the rootzone, this research was conducted for a year in the Research Greenhouse of the Department of Horticulture, College of Agriculture, Isfahan University of Technology in 2014. The research was a factorial experiment based on completely randomized design with 3 replications, three N treatments (100% N in Johnson solution (10.11 mM) as control, 75% N in Johnson solution (7.582 mM) and 50% N in Johnson solution (5.055 mM)), two temperatures (15 °C as low temperature in the root zone and 25 °C as optimum root zone temperature) with different rootstocks including Cucurbita Lagenaria siceraria (Rls), Cucurbita moschata cv. Ferro (Rcf), Cucurbita moschata cv. Babol (Rsb), Cucurbita moschata cv. Sari (Rcm), Cucumis sativus cv. Isfahan (Res) and Cucumis sativus cv. DavosII (Rn) as control. Results showed that the highest fresh weight of the shoots and roots and roots dry weight belonged to the Rls, and the Rcm rootstock had the highest dry weight of the shoots. The effect of root zone temperature stress on shoot growth was more than N stress and caused a greater reduction in shoots fresh and dry weight. The effect of low rootzone temperature, compared to N stress, had greater effect on the photosynthesis of Rcm, Rls, Res and Rn rootstocks. It seems that Rcm and Rls had better ability in maintaining of cucumber growth under N stress than temperature stress. The Rcf maintained the best growth conditions in low root zone temperature. In general, comparing the two stresses, (N and low temperature stress in grafting, in growth regulation), different levels of N were more effective than temperature stress

In order to evaluate the effect of different Trichoderma isolates on reducing the effects of drought stress on Polianthes tuberose, two factorial experiments were carried out based on completely randomized design with three replications. The first factor in the first experiment was bi isolate, and in the second experiment was isolate 65 of Trichoderma harzianum, each at three levels (0, 10, 20% v/v) and the second factor was three levels of drought stress (25, 50, 100% of pot capacity). Results showed that both isolates increased fresh and dry weight of the biomass and root dry weight of Polianthes tuberose plant under stress conditions. The fresh weight of the biomass was increased by 20% in 25% stress by bi isolate and 29.5% by isolate 65, indicating that the growth of Polianthes tuberose in the presence of Trichoderma fungus increased. Proline content was increased by 40 and 32% by isolates bi and 65 in 25% stress compared to 100% pot capacity. The relative water content and leaf area were increased by applying different levels of the two fungi with increasing stress levels. The leaf area in the 25% stress and 20% fungus treatment were increased by 26 and 24%, respectively, in isolates bi and 65, compared to fungus-free pots. It seems that the isolates bi and 65 of Trichoderma harzianum have different effects under drought stress conditions. In terms of stress, 100% pot capacity and bi-isolate treatment, the root dry weight, fresh and dry weight of biomass, relative water content and leaf green area were more than the same traits in isolate 65 treatment.

The lead-zinc industries are known to be one of the high-risk industries in terms of the environmental issues. In this research, 15 samples of waste (cake) from Zanjan Lead and Zinc Factory were collected and six samples were selected for adding to soil according to type and concentration of heavy metals. Then, lettuce was planted in soil samples treated with different cakes. After harvesting the plants, the plant growth indices, concentration of heavy metals in plant roots and leaves, and available concentration of heavy metals in the cultivated soil were measured. This research was carried out as a completely randomized design, in which, six types of cakes were tested at three levels (0.25, 0.5 and 1%) with three replicates and three control samples (without adding the cakes). Results indicated that the highest amount of pollution for total concentration of heavy metals was related to Cd (168333 mg/kg), Zn (100000 mg/kg), Fe (91666 mg/kg), Mn (25566 mg/kg) Pb (13483 mg/kg) and Ni (7966 mg/kg), and for available concentration of heavy metals was related to Mn (21400 mg/kg), Zn (16400 mg/kg), Cd (4520 mg/kg), Pb (2371 mg/kg), Ni (194 mg/kg) and Fe (11.2 mg/kg). Available concentration of heavy metals in soils treated with cakes was reduced by uptake of these metals by lettuce

An experiment was conducted as split plot based on the randomized complete blocks design, in greenhouse complex of Shahid Chamran University of Ahvaz in 2017. The main plot consisted of light treatment at two levels [a) sunlight (control), b) sunlight + red and blue LEDs (50:50%) with light intensity of 70 μmol/m2s for 15 hours (from 5 PM to 8 AM as night light] and the subplot was six greenhouse lettuce cultivars (Black Seed Simpson, Green Ice, Vivian, Tom Thumb, Red Salad Bowl and Salad Bowl). Results of the experiment showed that some of the measured traits were influenced by cultivar and light increase and some of them were under the influence of interaction effects of cultivar and light and were significant at 1% level. Maximum fresh and dry weight of leaf, fresh and dry weight of stem, number of leaves and calcium content were observed in night light treatment. Maximum and minimum values of leaf nitrate content were observed in Tom Thumb cultivar and control treatment (1723 μg/g dry weight) and Green Ice cultivar and night light (1023 μg/g dry weight), respectively. Maximum and minimum values of calcium content were observed in Black Seed Simpson cultivar and night light (1477 μg/g dry weight) and Tom Thumb control treatment (271.1 μg/g dry weight), respectively. According to the results of this experiment, by increasing the night light, it is possible to enhance the quantitive growth of the leafy lettuce cultivars by 90%, and also increase the quality of their yield

Culture medium and nutrition are two important factors in determining the quantity and quality of greenhouse products. Accordingly, a factorial experiment was conducted based on completely randomized design on strawberry (cv. Aromas) in the greenhouse of Department of Horticulture, University of Kurdistan, Sanandaj, Iran. The first factor was two culture media (mixture of perlite and cocopeat with equal volumetric percent, and pumice). The second factor was three concentrations of humic acid (0, 300 and 600 mg/L). The third factor was harvesting period. Quantitative and qualitative characteristics of the fruits were evaluated in different harvesting periods. Results indicated that yield and qualitative characteristics of fruits were highly influenced by culture medium and humic acid. The highest average fruit yields were obtained in perlite-cocopeat medium (107 g/plant) and pumice medium (85.4 g/plant) from plants treated with 600 mg/L humic acid. The highest average fruit firmness (6 N), total soluble solids (6.19%) and soluble carbohydrate (58 mg/100 g fresh weight) were obtained in plants grown in pumice medium and fed with 600 mg/L humic acid and the highest average phenol (113 mg gallic acid/100g fresh weigth ) and vitamin C (34 mg/100 g fresh weight) were obtained from plants grown in perlite-cocopeat medium and fed with 600 mg/L humic acid. In general, and based on total measured traits, perlite-cocopeat medium, fed with 600 mg/L humic acid as fertigation method, is recommended for favorable quantitative and qualitative production of strawberry (cv. Aromas)