نشریه روابط خاک و گیاه
پیاپی 13 (بهار 1392)

To alleviate water scarcity problem in arid and semiarid regions of Iran, different irrigation methods such as deficit irrigation, pressurized irrigation and partial rootzone drying (PRD) method have been suggested. In PRD method, half of the rootzone is watered and the other half is kept dry intermittently. The objective of this research was to study yield, yield components and water use efficiency (WUE) of tomato, using PRD irrigation method and a growth stabilizer in two soil textures, under greenhouse conditions. The factorial experiment, based on complete randomizal design and three replications, included three irrigation managements (T1, full irrigation; T2, 50% of full irrigation, with PRD method and barrier; T3, 50% of full irrigation, with PRD method and no barrier), two levels of stabilizer (B1, spraying sodium salicylate and B2, without spraying sodium salicylate) and two soil textures (S1, clay loam and S2, sandy loam). Results showed that the highest plants (176.2 cm) were in T1 treatment and the shortest plants (131.3 cm) were in T3 treatment. With 50% reduction of water in T2 compared to T1 treatment, number of flower stems was decreased by 15.2%. The highest and the least biomass and fruit yield were measured in T1 (506.8 and 342.5 g per plant) and T3 (126.2 and 54.8 g per plant) treatments, respectively. WUE was increased by 9.9% (changing from T1 to T2) and was decreased by 71.4% (changing from T2 to T3). The highest and the least fruit yield (216.7 and 174.4 g per plant) were obtained in S2 and S1 soils, respectively. Sandy loam soil with production of 7.22 kg/m3 had higher WUE than clay loam soil, which produced 5.38 kg/m3. Application of stabilizer increased fruit yield by 16% and WUE by 16.86%. In general, the effect of PRD irrigation method (with barrier) and spraying sodium salicylate on reducing water use and increasing productivity in greenhouse production of tomato was positive and recommendable.

Aloe vera is a perennial liliaceous plant with succulent green leaves joined at the stem in a whorled pattern. It is highly appreciated due to its short growth period and high economic value among all the aloe species, and is used in pharmaceuticals, cosmetic products and food products. In order to improve Aloe vera cultivation in soilless culture, an experiment was conducted in 2011 in greenhouse of College of Agriculture, University of Guilan, Rasht, Iran, as a split plot bi-factorial in completely randomized design with four replications. Four nutrient solutions containing different levels of nitrate and potassium were the main plot, which were sampled at six different periods. Results revealed that the nutrient solutions affect measured traits after 5-6 months. In other words, in research programs for this plant, it is better to record the data for at least 5-6 months. In general, the nutrient solution containing 9.8 mM nitrate and 5.8 mM potassium lead to the best results in all sampling periods. In fact, Aloe vera plants respond positively to high levels of nutrients and in solutions containing the highest level of nitrate and potassium show the highest amount of measured traits.

In order to investigate the effect of form of nitrogen (N) [ammonium (NH4) and nitrate (NO3)] and calcium (Ca) levels of nutrition solution on quantitative and qualitative yield of cut rose flower (Rosa hybrida L.), cv. Vendentta, in soilless culture condition, an experiment was conducted in greenhouse of the National Ornamental Plants Research Station of Mahallat. The experiment was factorial, with completely randomized blocks design, and two factors including NH4 at three levels (0, 2.5 and 5.0 mM from 10 mM total N and the rest as NO3), and Ca at two levels (1.6 and 4.8 mM). Results showed that increasing NH4 concentration of nutrition solution from 0 to 2.5 mM, increased the number of cut flowers, peduncle length and fresh stem weight; whereas, 5 mM NH4 concentration decreased significantly the number of cut flowers, flower diameter, peduncle length, vaselife and fresh weight of stem. Increasing Ca concentration of nutrition solution enhanced significantly flower diameter and fresh weight of cut flowers. With application of NH4 in nutrition solution (increasing NH4 to NO3 ratio), Ca and K concentration of leaves was reduced, and P, Zn, Mn, Fe and B concentration was enhanced significantly. Increasing Ca concentration in nutrition solution enhanced N, Ca, Mn and B and reduced K, Zn and Cu in rose leaves significantly. According to the results of this experiment, application of 2.5 mM NH4 (25% total N of nutrition solution) along with 4.8 mM Ca, improved growth and some qualitative indices of rose flower (cv. Vendentta).

Gerbera (Gerbera jamesonii L.) is one of the most important cut flowers in the world and nutrient solutions are the most important elements that increase quality and quantity of gerbera flowers. In this study, the effect of adding silicon, as an important mineral, from two sources of potassium silicate and nano silica, was investigated on physiological traits of gerbera flower, cv. Yanara. In this experiment, various concentrations of potassium silicate and nano silica were applied in different treatments including spray of nano silica in two concentrations of 12.5 and 25 mg/L (based on SiO2), drench of nano silica in two concentrations of 12.5 and 25 mg/L (based on SiO2), drench of potassium silicate in two concentrations of 25 and 50 mg/L (based on SiO2) and control (with no treatment), in three replications. The results showed that nano silica in both forms and concentrations decreased fresh weight of the flowers, but increased under-stomatal carbon dioxide. Number of flowers was increased under the 25 mg/L nano silica treatment, compared to control. Although there was no significant difference between treatments in dry weight of flowers and all photosynthetic parameters such as transpiration, photosynthesis, water use efficiency, and stomatal conductance, but in general, nano silica increased number of gerbera flowers; while, potassium silicate could not improve the studied traits.

To investigate the effects of humic acid and mycorrhiza fungi on visual quality, some characteristics of roots and chlorophyll changes of ryegrass, an experiment was carried out in Research Greenhouses of Department of Horticultural Science, University of Tehran, in spring and summer of 2009. The ryegrass was “Speedy green” perennial ryegrass, which is composed of three lolium (Lolium perenne L.) cultivars. After autoclave of the soil, addition of inoculums of mycorrhiza fungi (Glomus mosseae and Glomus intraradices) to pots and sowing of the seeds, plants were given enough time to grow. After establishment, humic acid was sprayed on leaves at concentrations of 0 (as control), 100, 400 and 1000 mg/L, and the above-mentioned characteristics were measured until the 9th week after starting the treatments. The results showed that humic acid was significantly effective on chlorophyll a, b, and total chlorophyll content, root length and fresh and dry weights of roots; but had no effect on visual quality, root volume and colonization percentage. Mycorrhiza fungi were effective on all characteristics. Among the mycorrhiza fungi, G. mosseae was better than G. intraradices on root factors, while had no positive effect on aerial parts. Colonization percentage was almost equal in both fungi. The effect of mycorrhiza fungi on the above-mentioned characteristics, with respect to the inoculums solution, was probably due to the production of hormone-like effects and enhanced hypha density in soil.

Phosphorus (P) and nitrogen (N) are the most essential nutrients for plant growth. Deficiency of these elements causes a considerable loss of crop yield. Nowadays, using of biofertilizers in cultivation of strategic crops, such as greenhouse crops, is very important because of resolving the P and N deficiency. This research was carried out to evaluate the potential of rhizobacteria of valerian (as a medicinal plant) in phosphate solubilization, N fixation, as well as salinity tolerance in the root zone, in laboratory conditions. To do so, 40 bacteria were isolated from the rhizosphere of valerian, and their mineral-phosphate solubilizing activities were measured on solid and liquid Sperber media. Besides, N-fixation ability of the isolates in symbiosis with wheat was evaluated under greenhouse conditions. Results showed that 77.5% of the isolates had the ability to solubilize mineral phosphate. Two isolates belonging to Pseudomonas and Xanthomonas genera and two isolates belonging to Pseudomonas genus had the maximum ability for phosphate solubilization in solid and liquid media, respectively. Among the isolated bacteria, one isolate belonging to Pseudomonas genus, showed the highest symbiosis efficiency (132%). Furthermore, results of the salinity-tolerance test of the bacteria revealed that all of the isolated bacteria could tolerate 500 mM NaCl concentration and two isolates (belonging to Pseudomonas genus) were able to tolerate salinity of 1000 mM NaCl. Overall, it can be concluded that rhizobacteria of valerian have high potential to be used as biofertilizer.

Titanium (Ti) has beneficial effects on growth, physiology and metabolism of plants. On the other hand, there is a high concern to use the nano-fertilizers with technological progress. In this respect, a hydroponic experiment, was designed in which Ti and nano-titanium (N-Ti) were added to the nutrient solution (NS) in two concentrations of 1 and 2 mg/L; the NS without adding treatments was considered as control. The experiment had completely randomized design with four replicates, and the growth changes and photosynthesis attributes of tomato were studied. The results showed that the effect of N-Ti in NS on root growth was more than shoot and had more positive effect on dry and fresh weight of the roots in 1 mg/L treatment. Ti and N-Ti increased transpiration, photosynthesis and inter-stomata CO2 content. N-Ti showed more effectiveness than Ti on transpiration and photosynthesis and this effect was more pronounced at higher concentrations. The chlorophyll content, root volume, fresh and dry weight of shoot, and time to the emergence of the first flower did not change significantly by Ti and N-Ti treatments. Conclusively, Ti at higher levels and N-Ti, due to its tiny size and easiness of penetration into the roots, can be effective on some growth and photosynthetic characteristics of tomato.

To evaluate the effect of salinity (S) and vermicompost (V) on yield and concentration of nitrogen (N), phosphorus (P), potassium (K), iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), calcium (Ca), magnesium (Mg), sodium (Na) and chlorine (Cl) of spinach shoots cv. Virofly, a pot experiment was conducted in greenhouse, and arranged as factorial in a completely randomized design with three replications. Treatments included three V levels (0, 1 and 2%, w/w) and four S levels (0, 1, 2 and 3 g NaCl per kg soil). Electrical conductivity of the soil for these four S levels was 0.7, 4.5, 8 and 11.5 dS/m, respectively. Results showed that the highest yield of spinach shoots was obtained in 10% V treatment. Application of sodium chloride (NaCl) had no significant effect on shoot yield. Therefore, under the present experimental conditions, S threshold level for "Viroflay" cultivar was at least 11.5 dS/m, which is much higher than the level reported in literature for spinach (2 dS/m). Application of V increased concentration of N, P, K, Fe and Mg in spinach shoots, but decreased concentration of Mn, Zn, Cu, Ca, Na and Cl. Application of NaCl had no significant effect on the concentration of P, Fe, Mn, Ca and Mg. But, with the addition of NaCl, concentration of N, Zn, Cu, Na and Cl was increased in spinach shoots. In the absence of NaCl, application of V had no significant effect on Na concentration, but increased Cl concentration. Whereas, at 3 g NaCl level, application of V significantly decreased Na and Cl concentrations of shoots, compared to the application of NaCl alone. Therefore, application of V not only can increase plant growth, but also could be an effective solution to mitigate the negative effects of high concentrations of Na and Cl on growth of spinach, cv. Virofly, in saline soils.

Petunia is one of the most popular flowers in the urban greeneries. The effects of zeolite and vermicompost media on some quantitative and qualitative characteristics of petunia were studied in a greenhouse experiment. Treatments consisted of three levels of zeolite (2.5, 5 and 10 % w/w) and three levels of vermicompost (2.5, 5 and 10 % w/w). In control treatment, no zeolite and vermicompost was added to soil. The experiment was carried out as a completely randomized design with 3 replications. Plants grew for two months in the greenhouse. Then, they were cut from collar and leaves and shoots were separated. The measured characteristics were dry weight of shoots, dry weight of roots, number of flowers, number of leaves, flower diameter, plant height, and concentrations of total nitrogen, phosphorus, potassium and calcium in shoots. Results showed that application of vermicompost and zeolite increased dry weight of shoots, dry weight of roots, number of flowers, number of leaves, flower diameter, plant height, and concentrations of total nitrogen, phosphorus, potassium and calcium in plants. Vermicompost at the rate of 10% produced maximum amount of plant-growth parameters. Therefore, it is recommended to consider the zeolite and vermicompost for cultivation of petunia.

One of the main factors of an aggregate hydroponic system is to use a suitable plant media with local origin. Thus the objective of this research was to study the possibility of replacement of cocopeat as an imported material with local materials and the effects of such media on the growth and flowering characteristics of Rosa hybrida cv. Maroussia. A randomized complete blocks design experiment with four replications was conducted. The treatments were nine growing media: cocopeat (100%), perlite (100%), leca (100%), cocopeat (75%) + zeolite (25%), perlite (75%) + zeolite (25%), leca (75%) + zeolite (25%), cocopeat (50%) + perlite (50%), cocopeat (50%) + leca (50%) and perlite (50%) + leca (50%). Results indicated that plants grown in cocopeat and cocopeat + zeolite showed high vegetative and reproductive growth. The highest number of flowers per plant was observed in in cocopeat (8.31) and cocopeat + perlite (7.81) substrates, which had no significant difference with cocopeat + zeolite medium (6.87). Adding zeolite to cocopeat, perlite and leca improved length of flower bud and number of flowers per plant over their pure medium. Also, adding cocopeat to perlite increased fresh and dry weight of cut flowers and number of flowers per plant. Based on the results and availability of zeolite in Iran, mixture of cocopeat (75%) + zeolite (25%) is recommended.