نشریه روابط خاک و گیاه
پیاپی 19 (پاییز 1393)

Efficiency of the presence– absence sampling technique to evaluate densities of vegetable leafminer Liriomyza sativae Blanchard (Diptera: Agromyzidae) larvae was tested by weekly sampling of a greenhouse cucumber in Jiroft، southern Iran، during two growing seasons of 2009 and 2011. At first، spatial distribution of larvae and leafmines was determined separately by calculating Taylor dispersion index. Based on R2 and F values of regression analysis، Taylor''s power law model provided suitable description of variance/mean relationships. The b values ranged from 1. 174 to 1. 317 (for larvae) and from 1. 181 to 1. 219 (for leafmines). Taylor indices were used in Wilson and Room model to evaluate the efficiency of presence– absence sampling technique. The results of Chi-square test showed that there was no significant difference between predicted and observed frequencies of infested leaves in each sampling. The mean mines and larval density may be precisely estimated by a proportion of the infested leaves. In this way، the required time and cost would be greatly reduced.

In order to simulate different methods of deficit irrigation through saline tension application، on physical characteristics of Caopea been roots، a study was carried out in Sari Agricultural Sciences and Natural Resources University greenhouse. The research was carried out in 2001، in completely randomized block with 5 treatments and 3 replications and under hydroponic cultivation under Hogland culture medium. The treatments were: no-tension (WS) (Ec=0. 8 mmhos/cm) DS1 and DS2 in which the whole roots were in solutions of EC=2. 3 mmhos/cm and EC=3. 6 mmhos/cm، respectively. PRS1 and PRS2 which root divided in two parts and in one part no- tension medium and in another part roots were in the solutions of EC=2. 3 mmhos/cm and EC=3. 6 mmhos/cm، respectively. 16 stage from roots were photographed for 45 days after application of treatment and parameters of diameter، length، area and root volume were measured. The results showed that salinity treatments on length of root growth and hence on growth of area and volume had significant effect. As the cultivation medium with EC=3. 6 mmhos/cm، decreased the root growth severely in both WS and PRS، this amount of EC is not recommended for Caopea been growth.

This research was conducted to study the role of phenology in wheat cultivars’ reaction to salinity stress. The experiment was carried out as factorial، based on a randomized complete block design with three replications، in Bu-Ali Sina University، Hamadan، Iran. Treatments included four wheat cultivars (Alvand، Toos، Navid and Sayson) and five levels of water salinity (0، 4، 8، 12 and 16 dS/m). Results showed that except for emergence stage، the salinity stress had reductive effect on other phenological stages of wheat cultivars. Chlorophyll index، plant height، spike dry weight، percentage of fertile stem، spike length and grain and biological yield of wheat were reduced by salinity stress. Wheat cultivars showed significant differences in each one of the studied traits. Maximum salinity effect on phenology and other studied traits was obtained in Sayson cultivar. By increasing the salinity level، Navid and Toos cultivars showed fewer changes in most of the measured traits، as compared to two other cultivars. Overall، Toos cultivar was the most compatible cultivar to salinity stress because of the need for less cumulative growing degree day for completion of phenological stages and more stability of yield.

Silicon (Si) is one of the beneficial elements for plants، which improves quantity and quality of yield، decreases evaporation and transpiration and enhances plant resistance to abiotic stresses. In order to evaluate the effect of Si and nano-silicon (N-Si) on growth، morphological and photosynthesis attributes of tomato، cultivar Falcato، an experiment was carried out in a hydroponic system، based on a completely randomized design، with two Si and N-Si levels (1 and 2 mM) and Si-free nutrient solution (as control)، and four replications. Such traits as chlorophyll index (SPAD)، photosynthesis، nutrient uptake، stem diameter، relative water content and morphological changes like density of trichomes were measured during the experiment. At the end of the experiment، fresh and dry weights and root volume were measured. Results revealed that Si was more effective than N-Si on fresh weight and mesophyll conductance. Concentrations of 1 and 2 mM Si increased fresh weight and mesophyll conductance، respectively. However، this concentration did not affect dry weight and relative water content significantly. N-Si was more effective than Si on photosynthesis and photosynthetic relative water content. The highest photosynthesis and lowest transpiration rate was measured in 2mM N-Si. Application of Si and N-Si decreased relative water content and the least water uptake was in 2mM N-Si treatment. In conclusion، Si or N-Si، with 20-30 nm particle diameter and optimum tomato growth conditions (without abiotic stresses) increased photosynthesis، fresh weight، relative water content and decreased nutrient solution uptake under hydroponics.

To evaluate the effects of different levels of nitrogen (N) and salinity on yield and growth indices of tomato، a factorial experiment with a completely randomized design and three replications was performed in greenhouse conditions. Treatments included four levels of salinity (0. 5، 2. 5، 4. 5 and 6. 5 dS/m as NaCl) and four levels of N (0، 60، 120 and 240 kg/ha). The results showed that fruit yield، plant height، shoot dry weight and leaf surface area were decreased with an increase in salinity level. The highest and the lowest values for these traits were measured in treatments with 0. 5 and 6. 5 dS/m salinity level، respectively. But، root dry weight increased with an increase in salinity level. The highest fruit yield and plant height were obtained from the application of 120 kg N /ha، which were not significantly different from those obtained from the application of 240 kg N/ha. The lowest fruit yield and growth indices were measured in treatments not receiving N. The highest fruit yield and plant height were measured in the treatment with salinity level of 0. 5 dS/m، receiving 120 kg N/ha. The highest shoot dry weight and leaf surface area were obtained from the treatment with salinity level of 0. 5 dS/m، receiving 240 kg N/ha. The lowest plant growth indices were observed in the treatment with salinity level of 6. 5 dS/m، not receiving any N. The highest root dry weight was measured in the treatment with salinity level of 6. 5 dS/m، receiving 120 kg N/ha. The least root dry weight was obtained in the treatment with salinity level of 0. 5 dS/m but not receiving any N. The results of this research showed that in areas with saline irrigation water، application of proper amount of N can alleviate the negative effect of salinity on yield and growth indices of tomato plant. The amount of required N to obtain maximum yield decreases as the level of salinity increases.

To study the effects of potassium (K) and drought stress on growth indices and mineral content of safflower leaf، a factorial experiment with 12 treatments and three replications was performed، using a completely randomized design، in the greenhouse of Soil Science Department، Zanjan University، Iran. The experimental treatments were a combination of four levels of K (80،130،180 and 230 mg/kg) and three levels of drought stress (irrigation at 100% FC، 60% FC and 30% FC) applied to the pots containing 5 kg soil. Results showed that drought stress reduced plant height، leaf area، dry weight of aerial parts and relative water content of leaf but increased the chlorophyll index of leaves. Drought stress also decreased concentration of zinc (Zn)، manganese (Mn)، copper (Cu)، phosphorus (P)، nitrogen (N) and calcium (Ca) in leaves but increased iron (Fe) and K content of leaves. Application of K increased all the measured growth indices. It also increased concentration of K، Fe and Cu and decreased concentration of N، P، Ca، Mn and Zn in leaves. In general، drought stress reduced dry matter production and disturbed ionic balance in safflower. But، application of K reduced the deteriorative effects of drought stress on safflower.

Mycorrhizal fungi are capable of symbiosis with plants. They improve plant growth by increasing absorption of nutrient elements and decreasing salinity and toxicity of some elements. In the present research، the effect of different salinity levels and Mg/Ca ratios on mycorrhiza colonization of Glomus sp. and vegetative traits of Sorghum bicolor was studied in a factorial greenhouse experiment، based on a completely randomized design with 3 replications. The factors were two mycorrhiza levels (control and inoculated with mycorrhiza)، three salinity levels (2، 5 and 10 dS/m) and four Mg/Ca ratios (0. 5، 1، 2 and 4). Results showed that shoot and root weight (dry and wet) and shoot length decreased with increased salinity، but the decrease in the traits of inoculated treatments with mycorrhiza was significantly lower than non-treated samples (P<0. 05). Colonization percentage in salinity level of 10 dS/m decreased from 62. 17% (control) to 30. 67%. Both dry and wet weight of root and shoot and colonization percentage increased as Mg/Ca ratio increased، and inoculated plants showed more increase in wet and dry weight. Comparison of interaction effects of Mg/Ca ratio and mycorrhiza clearly showed that colonization percentage was significantly increased. It seems that inoculation has an important role in increasing growth parameters and decreasing negative effects of salinity and magnesium in sorghum plant.

In order to investigate the effect of different levels of Cu and Zn on absorption of micronutrient (Cu، Zn، Fe and Mn) and macronutrient (P) in root and shoot Satureja hortensis، an experiment was conducted as factorial based on complete randomized design with three replications. The treatments consisted of three levels of Cu (0، 5 and 25 mg/kg CuSO4) and three levels of Zn (0، 10 and 50 mg/kg ZnSO4) and their combination. The application of adequacy levels of Zn (10 mg Zn kg-1) increased the concentration of of Zn، Cu and Mn of shoots by 85. 36 %، 53. 20% and 66. 08%، respectively. When 50 mg Zn kg-1was applied، the concentrations of Cu، Fe and Mn were decreased by 8. 38%، 12. 09% and 51. 99%، respectively. Application of adequate levels of copper (5 mg Cu. kg-1) increased the concentrations of Cu، Zn and Mn، by 118. 5%، 19. 76% and 63. 21%، respectively. The excess level of copper (25 mg Cu. kg-1) decreased the concentrations of Cu (15. 2%) and Fe (7. 99%) in the shoots، while increased Mn content (201. 89 %). Amounts of Cu and Zn were not detected in the essential oil. In general، it can be concluded that a negative interaction occurred between copper، zinc and iron، when higher Cu and Zn concentrations were applied. Also، due to negligible transport of elements into the essential oil، cultivatin of S. hortensis in the soil with moderate pollution could be considered.

Leafy vegetables play a crucial role in human dietary. Excessive application of nitrogen fertilizer leads to accumulation of high levels of nitrate in the tissues and causes further consequence. In order to evaluate the impact of zinc and harvest times on the reduction of nitrate accumulation and nitrate reductase activity، an experiment was conducted as completely randomized design with factorial arrangement and three replicates in Hoagland and Arnon nutrient solutions. Treatments were two levels of zinc (7 and 50 µg. L-1)، two harvest times (29 and 46 days) and two plants of lettuce and spinach. The results indicated that with increasing zinc concentration، nitrate concentration in lettuce shoots in both times decreased and nitrate concentration in roots decreased during the second harvest، whereas no reduction was found in roots and shoots of spinach plants. Nitrate reductase activity was increased in lettuce and spinach plants with application of high zinc levels. Reduced enzyme activity، and increased nitrate accumulation was observed over time in both experimental plants. The results of this study indicated that nitrate metabolism in plants affected by activity of nitrate reductase enzyme، the species of plant، harvest time and plant nutrients such as the zinc.

Cherry tomato، with small fruits، is one of the several varieties of tomato which is rich in vitamins such as C، A and K and antioxidant agents like lycopene. Therefore، it is very important from pharmaceutical and food perspectives. This research was carried out to optimize the best culture medium for micropropagation of this plant using single node culture technique under in vitro conditions. Results showed that the best treatment for micropropagation of cherry tomato plant، considering regeneration percentage، rooting percentage، shoot length، root length and number of internodes was basal MS medium supplemented with 1 mg/L Kin and 1 mg/L NAA، in which shoot length and number of internodes were highest among the treatments. All the plantlets that were transferred to the greenhouse survived and reached the fruiting stage. Maximum weight of fruits was obtained from explants grown in the MS medium (containing 1 mg/L Kin and 1 mg/L NAA).

Application of nitrogen sources in nutrient solution of soilless culture systems is one of the important factors in rose production. In order to investigate the effects of different ratios of nitrogen (N) source in nutrient solution on mineral concentration and vase life of rose (Rosa hybrid L. cv Dolcvita)، an experiment was conducted as a randomized complete block design in a commercial greenhouse in Yasouj city with seven ratios of NO3-: NH+4: Urea (0:100: 0، 50:50: 0، 0:0: 100، 50:0: 50، 50:25: 25، 70:15: 15 and 100:0: 0)، three replications، and two observations per replication. Results showed that by increasing ammonium and urea in nutrient solution، concentration of macro elements such as N، P، K and Ca deceases sharply. The lowest Ca concentration was observed in plants fed with 0:100: 0 NO3-: NH+4: Urea ratio. Higher ratios of nitrate in nutrient solution increased the amount of N، P، K and Ca. The amount of micro elements (Fe، Zn and Cu) showed a sharp decline by increasing ammonium and urea in nutrient solution. However، with an increase in nitrate concentration of nutrient solution، the concentration of micro elements increased. When the amount of urea increased in nutrition solution، vase life was reduced. The lowest vase life (11. 1 days) was observed in plants fed with nutrient solution containing 0:0: 100 NO3-: NH+4: Urea ratio. The highest vase life (17. 6 days) was obtained in the solution containing 50:25: 25 NO3: NH4+: Urea ratio. In general، application of 70:15: 15 or 50:25: 25 NO3-: NH+4: Urea ratio for improvement of quantity and quality of rose flower، cv. Dolcvita، is recommended in soilless culture system.

In order to study the effect of CPPU growth regulator on qualitative characteristics of cut rose (Rosa hybrida cv. Avalanche)، an experiment was performed as factorial، based on a completely randomized design، with four replications. In this experiment، the first factor included four concentrations of CPPU (0، 25، 50 and 100 mg/L) and the second factor was two application positions of CPPU (on the stem، and on the bud with a half cut ring 1 cm above the bud). The results showed that bud break، flowering time، length and diameter of flower shoot، flower diameter، number of internodes and fresh and dry weight of flowering stem were significantly (P< 0. 01) affected by CPPU treatments. The earliest bud break and flowering، longest stem، highest shoot and flower diameter and the highest stem fresh and dry weight were observed in the 50 mg/L CPPU treatment. However، application position of CPPU on the stem did not show any significant effect on the studied traits. Based on the results of this experiment، using CPPU growth regulator can increase growth of basal buds and enhance qualitative properties of the cut roses.

This experiment was conducted to evaluate the effects of different concentrations of humic acid (0، 100، 500 and 1000 mg/L) and spraying times (1، 2، 3 and 4 weeks) on growth and yield of the ‘Hanza’ stock flower (Matthiola incana). The experiment was factorial، based on a completely randomized design، with 16 treatments and 7 replications in each treatment. Results of analysis of variance revealed that there were significant differences in number of leaves، plant height and chlorophyll content in the evaluated plants in various humic acid concentrations. However، spraying intervals showed no significant differences for the measured traits. Also، time of planting to flowering was significantly shortened in plants treated with different concentrations of humic acid. The longest time from planting to flowering (139 days) belonged to control treatment، which differed significantly with plants treated by 500 and 1000 mg/L humic acid. Analysis of variance showed that the effect of concentration on maximum fluorescence (Fm) and effect of spraying intervals on minimum fluorescence (F0) and variable fluorescence (Fv) were significantly different at 5% probability level. The highest value of Fm، F0 and Fv (1453. 58، 270. 16 and 1183. 42، respectively) was found in plants treated by 500 mg/L humic acid. No significant difference was observed in photochemical-quantum yield (Fv/Fm) in response to different treatments.

The current experiment was carried out to study the effect of several media including sand، sand+cocopeat، sand+perlite، cocopeat+perlite and sand+cocopeat+perlite on rooting quality of stem cuttings in weeping bottlebrush plant (Callistemon viminalis). The study was done during the late August of 2010. Statistical design was completely randomized with three replications. After wounding the bottom section of stem cuttings، they were placed in the media، under glasshouse mist system. Cuttings were taken out of the beds 45 days later and parameters of rooting percentage، viability percentage of cuttings after transfer to pots، number of roots، highest root length، average root length، number of new branches and root dry weight were measured. Results showed that the effect of rooting media on highest root length، average root length، viability percentage of rooted transplants and number of new branches was significant. The highest average root length was observed in the sand+cocopeat medium and the highest root length was obtained in the sand، sand+cocopeat and cocopeat+perlite media. The maximum viability percentage of cuttings after transfer to pots was observed in the sand+cocopeat، sand+perlite and sand+cocopeat+perlite media. According to the obtained results، the sand+cocopeat medium could be recommended for rooting of weeping bottlebrush cuttings under mist system.