نشریه روابط خاک و گیاه
پیاپی 17 (بهار 1393)

In order to assess the effects of different levels of nitrogen (N) and foliar application of iron amino chelate on yield and growth traits of dill medical plant, a factorial experiment was conducted in 2011 using a completely randomized design and three replications. In this experiment, five levels of N (0, 50, 100, 200 and 400 kg/ha N from urea source) and two levels of foliar spray of iron amino chelate (with and without foliar spray) with concentration of 2 g/liter were used. At the end of growth period, fresh and dry weight of aerial parts, leaf, stem and roots, ratio of fresh and dry leaf weight to stem weight, height, stem diameter, 1000-seed weight and iron concentration and uptake in the aerial parts were measured. The results of ANOVA showed that the effects of N were significant on all measured traits, except fresh and dry weights of roots. Foliar spray of iron amino chelate increased significantly all measured traits, except fresh and dry weights of roots and plant height. The interactive effects of N and foliar spray were significant on all measured traits except the fresh and dry weight of stem, dry matter, ratio of fresh weight of leaf to stem, fresh and dry weights of roots, and iron concentration and uptake in the aerial parts. The highest fresh and dry weights of aerial parts (714.2 and 102.7 g/m2, respectively) were obtained from the application of 400 kg N/ha plus foliar spray of iron amino chelate. The lowest fresh and dry weights of aerial parts (199.7 and 45.6 g/m2, respectively) were obtained in the control treatment.

A greenhouse experiment, as hydroponic, was carried out in order to investigate the response of sunflower genotypes (Hison125, Iroflor and Bliezer) to different levels of salinity (0, 60 and 120 mM of NaCl) and Fe (0, 50 and 100 mM) in nutrient solution. The experiment was arranged as factorial, based on a completely randomized blocks design with four replications. Results showed that plant height, leaf area, shoot and root dry weight, ratio of shoot/root dry weight, K concentration, the ratio of K/Na concentration in shoot and roots were reduced and the concentration of Na was increased as the level of salinity was increased in the nutrient solution. There was a significant increase in the values of plant height, leaf area, shoot dry weight and the ratio of shoot/root dry weight as the level of Fe in the nutrient solution was enhanced from 5 to 50 mM. However, with a further increase from 50 to 100 mM, there appeared no significant changes in the amount of these traits. The interaction between genotype and Fe level was significant on the root dry weight and K concentration in the leaves. The lowest and the highest increase in root dry weight, in response to increased level of Fe, was observed in Hison125 and Bliezer cultivars, respectively. However, the difference between cultivars became less in treatments containing higher levels of Fe in the nutrient solution. Considering the K concentration in leaves, only Bliezer cultivar showed positive response to increasing Fe level. The interaction between salinity, genotype and Fe level was significant on the concentration of Fe in plant. Based on the results, increasing Fe concentration in the nutrient solution improves sunflower growth. However, the increased concentration of Fe could not significantly alleviate the negative effects of salinity.

In order to investigate the effect of different Fe sources on micronutrients concentration, especially Fe, in bell pepper (Capsicum annuum L. cv. California Wonder), under alkaline conditions and hydroponic system, a factorial experiment was conducted based on a completely randomized design with two factors of sodium bicarbonate (NaHCO3) at three levels (0, 10 and 15 mM) and four forms of Fe fertilizer (FeSO4, Fe-EDTA, Fe-DTPA and Fe-EDDHA) all at 10 mM and three replications. According to the obtained results, NaHCO3 stress caused a reduction in P, Fe, Mn, Zn, Cu and K, and an enhancement in Na concentration. When the FeSO4 source was used, an increase in NaHCO3 concentration resulted in severe chlorosis of the plants, although Fe concentration in this treatment not only was not lower than Fe chelate- treated plants, but also it was higher in some cases. In the presence of NaHCO3 and FeSO4 treatment, the concentration of Mn, Zn and Cu in plants was higher than in plants treated with Fe-chelates, which might be due to the reduction of Fe competition with these elements in this treatment. Therefore, although the use of Fe chelates, especially Fe-EDDHA, for Fe provision in alkaline condition is recommended, but its high concentrations may cause Mn, Zn and Cu deficiency in plants.

Bicarbonates and carbonates are the main factors of alkalinity in irrigation water. In order to determine suitable growth medium for gerbera (Gerbera jamesonii L. cv. Dafne) under alkalinity stress condition, a factorial experiment with completely randomized design with 4 replications was carried out. The experiment consisted of 7 levels of substrate (100% perlite, 100% cocopeat, 75% perlite+ 25% zeolite, 75% peat+25% perlite, 75% cocochip+25% perlite, 75% cocopeat+25% perlite and 75% vermicompost+25% perlite) and NaHCO3 at three levels (0, 20 and 40 mM). The results showed that the highest and the lowest pH values amounts belong to 75% peat + 25% perlite and 100% cocopeat substrates. Sodium bicarbonate treatment, depending on the kind of growth substrate and NaHCO3 concentration, decreased number of flowers, flower fresh weight, flower stem length, flower diameter, flower neck diameter, flower vase life and chlorophyll index; although, this treatment increased the phenolic compounds. The plants grown in 100% cocopeat substrate, when exposed to sodium bicarbonate, had better qualitative and quantitative traits, ability of higher accumulation of phenolic compounds and higher chlorophyll index, as compared to other substrates. Therefore, it is concluded that gerbera's tolerance to alkalinity is low and the use of pure cocopeat substrate could provide a useful tool to improve alkalinity tolerance of gerbera plants under NaHCO3 stress.

To study the effect of arbuscular mycorrhiza (Glomus mosseae) on growth of greenhouse cucumber (Cucumis sativus cv. Nahid) under bicarbonate stress originated from irrigation water, a completely randomized design was adopted in an experiment with four levels of bicarbonate in irrigation water (0, 400, 800 and 1200 mg/L), two levels of mycorrhiza (inoculated and un-inoculated plants) with five replications. Results showed that vegetative growth parameters (dry weight of root, stem and leaf, stem height and diameter, leaf number and surface area) of plants were reduced with increasing bicarbonate concentration, especially at 1200 mg/L, where more than 50% reduction in root and leaf dry weight was observed. Bicarbonate concentration above 800 mg/L caused around 50% reduction in stem dry weight and leaf area. Arbuscular mycorrhizal fungi had a prominent effect on maintaining of vegetative growth under bicarbonate stress, especially at 1200 mg/L. It can be concluded that vegetative growth of cucumber plant is reduced by bicarbonate stress and mycorrhizal symbiosis can ameliorate the adverse effects of bicarbonate.

Among the most important quality parameters of irrigation water used for greenhouse crops, alkalinity of water is considered critical due to its impact on pH of soil or growing medium solution. In this study, shoot and root Fe contents and SPAD index were investigated in non-grafted and grafted tomato (greenhouse tomato) plants onto five rootstocks (eggplant, datura, orange nightshade, local Iranian tobacco, and field tomato), exposed to 0, 5 and 10 mM NaHCO3 concentration, to determine whether grafting could improve alkalinity tolerance of tomato. Results showed that significant reduction of shoot and root Fe content under high NaHCO3 level was observed in both grafted and ungrafted plants. The highest reduction in the shoot Fe content was observed in control plants (greenhouse tomato) under 10 mM sodium bicarbonate. Values of SPAD index was decreased significantly at 5 and 10 mM NaHCO3 irrespective of rootstock type. Adjusted pH of the solution surrounding the roots in datura rootstock may have possibly a role in the reduction of bicarbonate-induced deleterious effects. Thus, it is concluded that using datura rootstock could improve alkalinity tolerance of tomato plants under NaHCO3 stress.

Poinsettia (Euphorbia pulcherrima) is a pot plant, which its colorful bracts form in short days. In order to increase the marketability of this plant, effect of spraying different concentrations of 2-chloroethyl-N, N, N-trimethyl-ammonium chloride (cycocle) growth retardant on the vegetative growth and flowering characteristics of poinsettia was investigated. The experiment was arranged in a completely randomized blocks design with three replications. Poinsettia plants were sprayed with different concentrations of cycocle (0, 500, 1000, 1500 and 2000 mg/L). At the harvest time, the vegetative characteristics, fresh and dry weight of aerial parts and roots, chlorophyll index and mineral elements’ concentration were measured. The results revealed that quality and quantity characteristics of poinsettia was significantly (P≤0.01) affected by various cycocle levels. Spraying the cycocle at 2000 mg/L increased chlorophyll content of the leaves. In 1500 mg/L chloromequat treatment, plant height was decreased; while number and area of bracts increased significantly as compared to the control. Also, effect of cycocle treatment on fresh and dry weight of leaf, stem, and roots was meaningful. Therefore, based on the obtained results, it seems that spraying of cycocle at 1500 mg/L level, made improving in the production characteristics of poinsettia.

Arabidopsis thaliana is a suitable model plant for genetic and molecular biology studies in higher plants. However, its hydroponic culture for biochemical and physiological studies is a challenge due to small size, capillary roots and little biomass at maturity. Several cultural systems have been suggested for Arabidopsis thaliana hydroponic culture, each having special advantages and disadvantages. Due to the difficulties of these cultural systems, two simple and economical hydroponic cultural systems are provided for Arabidopsis thaliana. In the first system, seeds were planted in solid MS culture medium in plates and then the seedlings were transplanted in polyethylene pots including ½ Hoagland or Gibeaut nutrient solution. In the second system, seeds were directly planted in a small drop of agar that was placed on the pores of pot’s lid. Several parameters such as root length, fresh and dry weight of roots and shoots and shoot to root ratio were compared in plants cultivated in different hydroponics cultural systems and plants grown in mixture of soil and moss as a common cultivation method. The results indicated that the greatest growth was obtained in plants grown in transplanting seedling method with ½ Hoagland nutrient solution and this method could be suggested for Arabidopsis thaliana hydroponic culture.

Tomato (Lycopersicon esculentum Mil.) is one of the most important economical vegetable in the world and its greenhouse production has expanded during the recent years. In this study, the effects of two pruning methods on yield and some fruit quality traits indices of two varieties of tomato (Newton and Oregon) were investigated. In the first experiment (florescence pruning), treatments were keeping 4, 6, and 8 florescence per plant. In the second experiment (fruit pruning), 4, 6 and 8 fruits were kept in each florescence. In each experiment, a non-pruned treatment was considered as the control. The results showed that although florescence pruning increased volume, length and mean weight of fruits, but it decreased the fruit yield. However, fruit yield of the 8 florescence per plant treatment was not significantly different from the control. Florescence pruning also increased pH and concentration of chlorophyll a and total chlorophyll in leaves. Although fruit pruning had positive effect on fruit volume, but decreased total yield in 4 fruits per florescence treatment. However, keeping 8 fruits per florescence did not show significant difference with control. Fruit pruning increased chlorophyll a and total chlorophyll content in 4 fruits per florescence treatment. According to the results of this research, fruit and florescence pruning had no significant effect on yield and qualitative traits of tomato and therefore are not recommended due to their costs.

Determination of copper (Cu) availability in soils is important in preferment quality and quantity of agricultural crops. To this aim, suitable extractant must be introduced. The objective of this greenhouse experiment was to evaluate several extractants to predict available Cu of cultivated bean, in 10 calcareous soils, untreated and treated with municipal sewage sludge. After one month of incubation of soils, available Cu was determined using 7 chemical procedures (DTPA-TEA, AB-DTPA, Mehlich 1, Mehlich 2, Mehlich 3, 0.1 N HCl and 0.01 M CaCl2). The results showed that Mehlich 3 and 0.01 M CaCl2 in treated and untreated soils extracted the highest and the lowest amount of Cu, respectively. Among the extractants used for untreated soils, significant correlation was found between extracted Cu using DTPA-TEA with concentration and uptake of Cu in shoots. In addition, in sewage sludge-amended soils, correlation between extracted Cu using DTPA-TEA, AB-DTPA and Mehlich 3 and concentration, dry matter and uptake of Cu was significant. In general, the results of this research showed that DTPA-TEA could be used to predict available Cu in untreated and sewage sludge-treated calcareous soils under bean cultivation.

In order to study the effects of salinity stress on morphological traits, essential oil content and ion accumulation in basil (Ocimum basilicum) plant under hydroponic conditions, a factorial experiment based on completely randomized blocks design with three replications was conducted on three landraces (Jahrom, Banafsh and Isfahan) and five NaCl salinity levels (0, 40, 80, 120 and 160 mM) in controlled greenhouse conditions. The results indicated a significant reduction in plant height, shoot dry weight and root dry weight due to increasing salinity level. Among the landraces, Banafsh landrace had the highest biomass. Also, with the increase in salinity level, sodium ion content of shoot and root increased. However, Ca2+ and K+ contents and Ca2+/Na+ and K+/Na+ ratios of both shoot and root decreased. These ratios were higher in shoots, as compared to roots, of all three landraces. Essential oil content increased with the increase in stress level. However, this much increase in essential oil content is not important at high salinity levels due to high reduction in biomass. This could be important at moderate stress considering produced biomass. Among the studied landraces, Jahrom landrace contained the highest essential oil content.

Plant roots, with respect to their intrinsic characteristics, have important role in both improvement and development of germplasms of drought resistant plants. This experiment was conducted to study direct and indirect effects of root morphological traits on grain yield of four triticale genotypes (three promising lines of ET-82-8, ET-82-15 and ET-79-17 along with the conventional Junillo-92 cultivar) under two available moisture levels in soil (irrigation after 50% moisture depletion in the root zone, as control) and moisture stress (irrigation after 80% moisture depletion in the root zone) as a randomized complete blocks design in factorial arrangement with four replications, in Research Greenhouse of College of Agriculture, Ferdowsi University, Mashhad, Iran, in 2008. The results showed that water stress caused a 9% reduction in root depth development. Also, the difference between deepest root in ET-82-15 and the shallowest root in Junillo-92 was about 8.2 cm. Delay in irrigation caused a 25% reduction in accumulated root length. The 43% difference between highest accumulated root length in ET-82-15 and lowest accumulated root length in ET-79-17 was significant at 1% level. The role of root morphology of these genotypes on seed production was different under various soil moisture conditions. In optimum soil water content, direct effect of accumulated root length with regression coefficient of 0.543 was more than water deficit conditions with regression coefficient of 0.286. On the other hand, direct relation of total root surface with grain yield was negative in normal moisture conditions and negative under water deficit. In general, it seems that accumulated root length and root surface are effective characteristics in seed production of these genotypes; total root surface has more important role in water deficit conditions, and accumulated root length in optimum soil moisture levels.