نشریه روابط خاک و گیاه
پیاپی 8 (زمستان 1390)

Increasing atmospheric CO2 concentration affects plant activities directly. In order to investigate the effect of CO2 concentration, an experiment was conducted at Research Greenhouse of College of Agriculture, Shiraz University, Shiraz, Iran. In this research, the effects of increasing CO2 concentration from 350 to 750 mg/L were studied on growth and yield of red bean (Phaseolus vulgaris, cv. Naz) at four irrigation levels (1.2 FC, FC, 0.8 FC and 0.6 FC). In order to control CO2 concentration, at the onset of the 4-leaf stage, pots were moved to wooden chambers covered with plastic. The results showed an average 15% decrease in evapotranspiration due to increasing the CO2 concentration. Also the results indicated an increasing effect of CO2 concentration on growth and yield of bean plants. Reducing the irrigation level to 0.6 FC caused the elevated CO2 concentration not to have any significant effect (P<0.05) on growth and yield of the red bean. By increasing the CO2 concentration, number of seeds/plant at FC and 0.8 FC irrigation treatments increased by 13 and 11%, respectively. Moreover, increasing CO2 concentration caused 20% increase in total seed yield. Total dry matter increased about 15% at higher CO2 level. The conclusion of this research was that increasing CO2 concentration has significant effect on yield and reduction of evapotranspiration of red bean.

One of the problems for unequal distribution of salts in the root media is toxicity of sodium (Na) and reduced uptake of some nutrients, particularly calcium (Ca) and potassium (K), by the roots growing in the saline section. There is a hypothesis that addition of Ca and K to these systems might alleviate salt-induced damages to plants. This study was carried out to evaluate the effect of Ca and K application on fruit yield, water use and crop per drop (CPD) of tomato (Lycopersicon esculentum var. Falcato F1) plants grown in a hydroponic system with unequal distribution of salts in the root media. Tomato roots were divided into two equal splits and one half was immersed in the full Johnson nutrient solution. In the other root half, 40 mM NaCl solution, alone or in combination with KCl (6 mM), CaCl2 (4 mM), K+Ca (3+2 mM) or half-strength Johnson nutrient solution, was applied. A control treatment was also used in which both root splits were immersed in the Johnson nutrient solution (C). The root splits were exchanged every 7 days. Results showed that addition of 40 mM NaCl in one side of the root media resulted in reduction of fresh and dry weight of root and shoot, stem diameter, shoot height, number of leaves and fruit yield of tomato in comparison with the control treatment. Addition of Ca, K+Ca and half-strength Johnson nutrient solution to the saline part of the root media increased significantly the root and shoot growth and fruit yield of tomato compared with the sole application of saline solution. In contrast, addition of K could not alleviate the adverse effects of salinity and even reduced the fruit yield. Application of 40 mM NaCl in one side of the root media reduced significantly the plant water use. Addition of Ca, K+Ca and half-strength Johnson nutrient solution to the saline part of the root media resulted in significant increase in CPD. Addition of Ca, K+Ca and half-strength Johnson nutrient solution caused replacement of 48, 43 and 43% of nutrient solution with saline water, respectively. According to the results of this study, in case of dynamic and non-uniform distribution of salts in the root media, by addition of Ca to the saline solution, it would be possible to replace about half of the crop water demand with saline water, with no significant fruit yield reduction.

Interveinal chlorosis induced by iron deficiency is considered to be one of the problems in rose production in greenhouses all over the world. This experiment was conducted to elucidate the capability of chlorophyll fluorescence imaging technique to recognize early iron deficiency and also determination of relationship between leaf iron concentration and leaf chlorophyll content index and photosystem II photochemical efficiency of rose flower (Rosa hybrida L., cv. First Red). Rose plants were grown and subjected to 5 levels of iron (1.5, 3, 6, 12 and 24 μM) based on randomized complete blocks design with 4 replicates in hydroponic greenhouse of Wageningen University, The Netherlands. The results revealed that increased concentration of iron in nutrient solution from 1.5 to 24 μM led to the meaningful increase of average photosystem II photochemical efficiency from 0.062 to 0.590 (P<0.01). This was clearly obvious in the map of photosystem II photochemical yield of rose leaves. The results indicated significant (P<0.05) correlations between leaf iron concentration and leaf chlorophyll content index (r= 0.91) and average photosystem II photochemical efficiency (r= 0.85). Also, a significant correlation (P<0.05) was found between leaf chlorophyll content index and photosystem II photochemical efficiency (r=0.86). The results clearly demonstrated that it is possible to detect early hidden hunger of iron in rose flower with the use of chlorophyll fluorescence imaging and therefore increasing the yield and quality of rose flower in greenhouses.

Periwinkle (Catharanthus roseus L.) belongs to the Apocynaceae family and accumulates more than 130 terpenoid indole alkaloids (TIAs), of which two dimeric alkaloids Vinblastine and Vincristine have antineoplastic activity and are useful for treatment of various cancers. Therefore, the production of these drugs has been emphasized in plant tissue culture. In this research, 25 treatments of plant growth regulators to produce callus from leaf explants and seven treatments for regeneration of calli were considered. Analysis of variance showed that the effect of different hormonal treatments in the production of callus from leaf explants is significant (P<0.01). Application of 0.1 mg/L BAP and 5 mg/L NAA in nutrient media produced a lot of calli and roots. In addition, nutrient media containing activated charcoal and without it were found to be suitable for production of callus and regeneration, respectively. In conclusion, the results showed that indirect regeneration of leaf explants is not a suitable method for micropropagation of periwinkle due to difficult regeneration of callus, probability of mutation and lower number of produced branches. But this method can be utilized for production of secondary metabolites.

This experiment was carried out at National Research Station of Ornamental Plants, Mahallat, Iran, to investigate the effect of different substrates on growth and yield of gerbera flower. The experimental design was randomized complete blocks, using 14 treatments with 3 replications as: fine sand, peat + fine sand (25% + 75%), peat + fine sand (50% + 50%), perlite + peat (75% + 25%), perlite + peat (50% + 50%), perlite + peat (25% + 75%), perlite + peat + expanded clay (25% + 70% + 5%), perlite + peat + expanded clay (50% + 25% + 25%), perlite + peat + expanded clay (25% + 50% + 25%), perlite + expanded clay (50% + 50%), coco peat, coco peat + perlite (75% + 25%), coco peat + perlite (50% + 50%) and coco peat + perlite + expanded clay (50% + 25% + 25%). Results indicated that the medium containing perlite + peat + expanded clay (25% + 70% + 5%) had significant difference with other media in number of flowers, flower disk diameter, shoot diameter, shoot neck diameter, flower height and vase life. In this media, number of flowers, flower disk diameter, shoot diameter, shoot neck diameter, flower height and vase life were 207 per m2/year, 12.4 cm, 0.8 cm, 0.58 cm, 54.5 cm and 11.6 days, respectively. With respect to the quantitative and qualitative traits of gerbera flower, among the studied substrates in this experiment, mixture of perlite + peat + expanded clay (25% + 70% + 5%) was the best medium and could be recommended to the gerbera growers.

Rose flower (Rosa hybrida) is appreciated for its beauty, fragrance and long period of flowering. To study the response of cut rose flower to bio-fertilizers, a factorial experiment was performed, with completely randomized design and four replications, in hydroponic greenhouse of Alandasht, Astane Ghods Garden, Mashhad, Iran, during 2009-2010. The first factor was six cultivars of rose flower including: Red ferover, Classic cezaanna, Rock feller, Rimini, Maroussia and Orange juice. The second factor was three biological fertilizers including biofarm, nitrajin and nitroxin and a no-inoculated treatment (control). In this experiment, traits such as leaf area, number of nodes, number of branches, first flowering occurrence, vase life and percentage of nitrogen, potassium and calcium were measured in each treatment and the means were compared by Duncan Multiple Range Test. Results showed that the effect of cultivar and compound effect of cultivar and fertilizer for number of nodes, number of branches, first flowering date, vase life, leaf area and nitrogen, potassium and calcium concentration were significant (P<0.05). The effect of bio-fertilizer treatments on leaf area and concentration of nutrients was significant (P<0.05). The highest concentration of nutrients was observed in Red ferover cultivar. Interaction effect of cultivar and bio-fertilizer treatments showed that in the Red ferover, Classic cezaanna and Maroussia cultivars, the fertilizer treatments increased nitrogen concentration in the leaves. The biofarm and nitroxin fertilizers increased leaf calcium concentration in Red ferover and Rimini cultivars significantly (P<0.05). The nitrajin and nitroxin treatments reduced calcium concentration, as compared to control, in the Rock feller cultivar.

To study the effects of different levels of N, K and Mg on yield and growth indices of strawberry, a factorial experiment with completely randomized design and three replications was performed. Treatments included three levels of N (110, 220 and 330 mg/L), three levels of K (120, 240 and 360 mg/L) and three levels of Mg (12, 24 and 48 mg/L) that were applied to strawberry (cv. Gavita) in a hydroponic system. The yield, number of fruits, fresh and dry weight of aerial parts and roots of strawberry were measured in each treatment. Results of ANOVA showed that the effects of different levels of N were significant on yield and growth indices of strawberry. The yield decreased as the level of N increased in the growth medium, such that the highest yield was obtained in the 110 mg/L N treatment. The effects of K levels were also significant on yield and growth indices of strawberry, except for number of fruits. The yield decreased as the level of K increased. The highest yield was observed in the 120 mg/L K treatment. The Mg levels had significant effects on yield and fresh and dry weight of aerial parts of the plants. The highest strawberry yield was obtained when 24 mg/L Mg was used in the hydroponic culture. All interactive effects of N, K and Mg were significant on yield and growth indices of strawberry, and the highest yield was obtained when the levels of N, K and Mg in the hydroponic solution were 110, 120 and 24 mg/L, respectively. In general, these levels of nutrients are recommendable to obtain maximum strawberry yield in hydroponic media.

Utilizing sewage sludge as a source of cheap fertilizer and rich in nutrients is common in some parts of Iran. But, too much application causes accumulation of heavy metals in soil, which results in soil pollution and transfer of this pollution to food chain and endangers human and animal health. The aim of this research was to investigate the effect of biological sludge of Tabriz petrochemicals complex on some heavy metals concentration in spring barley grown in a calcareous soil after 6 months of incubation. The experiment was conducted in greenhouse conditions with 5 levels of 0 (control), 25, 50, 75 and 100 ton/ha sewage sludge, in three replications, based on complete randomized blocks design. Soil analysis showed that application of biological sludge significantly increased DTPA extractable Fe, Zn, Mn, Cu and Cd (except 25 ton/ha treatment) compared to the control. The results of plant analysis showed an increase of Fe, Zn and Mn in shoots and Zn and Mn in roots, compared to the control. But elevation of root Fe content was not significant. The amount of Cu and Cd in shoots and roots was below the detection limit of the instrument. Overall, it was concluded that although the application of biological sludge increased the content of heavy metals in soil, but its effect on concentration of toxic elements, such as Cd, in plants was not significant.

In order to assess the effect of salinity on root traits and yield of two wheat cultivars, an experiment was conducted in Agricultural, Medical and Industrial Research School, Nuclear Science and Technology Research Institute, Karaj, Iran, using factorial experiment based on complete randomized design with 3 replications. The first factor included sensitive wheat cv. (Tajan) and tolerant cv. (Bam) and the second factor was salinity stress at four levels (6, 8, 10 and 12 dS/ m). In each treatment, 10 days after anthesis, the variation of root dry weight, shoot dry weight, root/stem ratio, and root area and volume were analyzed. The results showed significant reduction (P≤0.01) in root dry weight, root area and root volume per plant. Root/shoot dry weight ratio decreased 35.1% and 8.2% in Tajan and Bam cultivars, respectively, at 8 dS/m compared to 6 dS/m. Results revealed that grain yield per plant was affected by root dry weight, as the highest grain yield was observed in Bam cultivar. Increased grain yield in this cultivar was due to higher root dry weight. Also, Tajan cultivar had the lowest grain yield and root dry weight in 12 dS/m treatment. There were positive correlations among root surface and volume with root dry weight and therefore with grain yield. Therefore, based on the parameters studied in this experiment, it can be stated that a large part of the traits associated with sensitivity or tolerance of wheat cultivars to salinity could be attributed to their roots’ characteristics.