نشریه روابط خاک و گیاه
پیاپی 16 (زمستان 1392)

For production of cut roses، as the most favorable and profitable crop in floriculture industry، optimization of growing conditions، especially temperature، is very important in all year round. This study was carried out to evaluate the efficiency of fan and pad cooling system of a cut rose research greenhouse with plastic tunnel structure، as a sample of arid and semiarid greenhouses of Iran. The main effective factors in efficiency of greenhouse cooling system including solar radiation، received light، and inside and outside temperature were measured from 9:00 am to 6:00 pm in 10 warmest days of summer of 2009. Then، the warmest day was selected for final analysis. Based on the past research results، the efficiency of pad–fan cooling system was calculated at different locations of the greenhouse، at different hours of the day، and the cooling efficiency at the hottest hour was considered as the final potential of the system. The results showed that efficiency of fan-pad system in Mahallat conditions was about 50-100 percent depending on the location in the greenhouse (distance to pad) and climatic conditions at data-gathering time (received light، air temperature and relative humidity inside the greenhouse). However، cooling efficiency at the warmest hour of the hottest day of the year was estimated as 75% at air entrance of the pad.

In order to investigate the effect of integrated management of phosphorus (P) fertilizer and phosphate solubilizing microorganisms on nutrients concentration and yield of two barley cultivars، a factorial greenhouse experiment was carried out based on randomized complete blocks design with three replications in 2011. Treatments consisted of two barley cultivars (Bahman and Fasih) and five types of P fertilizer management (seed inoculation with Pseudomonas fluorescens strain 103 + 100% recommended P fertilizer، seed inoculation with P. fluorescens strain 103 + 75% recommended P fertilizer، seed inoculation with P. fluorescens strain 103 + 50% recommended P fertilizer، seed inoculation with P. fluorescens strain 103 + no use of P fertilizer، and no inoculation and no use of P fertilizer as control). The results showed that increasing P fertilizer application increased significantly the plant height، main stem diameter، chlorophyll a and b and biological yield of the two barley cultivars. The highest main stem height، chlorophyll b content، nutrients concentration and plant dry weight was obtained at seed inoculation + 100% recommended P fertilizer treatment. Maximum stem diameter and chlorophyll a was observed at seed inoculation + 75% recommended P fertilizer. Also، Bahman cultivar had the highest forage production as compared to Fasih cultivar. According to the results، it can be stated that integrated management of growth promoting bacteria and improves yield and nutrients’ concentration.

In order to investigate phosphorus efficiency (PE) of the barley genotypes in the presence of phosphate-solubilizing microorganisms (PSMs)، a greenhouse factorial experiment was conducted as a completely randomized blocks design and 3 replications with 10 Iranian and foreign barley genotypes. The effects of different phosphorus (P) fertilizer treatments including control (P0)، phosphate rock (RP)، phosphate rock inoculated with phosphate solubilizing fungi (RP+F)، phosphate rock inoculated with phosphate solubilizing bacteria (RP+B)، phosphate rock inoculated with both fungi and bacteria inoculum (RP+B+F)، and soluble phosphate (PS) was studied. After 9 weeks، plants were harvested and shoot dry weight (SDW) and P concentration (PC) was measured and then PE indices were calculated. The results indicated that barley genotypes had significant differences (P<0. 01) in the SDW، PC، P content (TP)، P acquisition efficiency (PACE) and P utilization efficiency (PUTE). Gara-arpa genotype and line AltICB-98 produced the highest and Rihane-03 genotype produced the lowest shoot dry mass at the P-free treatment (P0). The inoculation with PSMs significantly increased plant growth parameters and PACE as the fungi inoculation was more effective than bacteria and mixed inoculation of fungi and bacteria. With fungi inoculation، the average PC increased from 1. 58 to 2. 9 mg/g SDW، PACE from 0. 12 to 0. 27 and PE from 0. 40 to 0. 69. Among the varieties، Yea-168 was efficient in P acquisition، Sahand was efficient in P utilization، and Gara-arpa and line AltICB-98 were efficient in both acquisition and utilization of P. Thus، it is concluded that selecting P-efficient varieties along with inoculation by phosphate-solubilizing microorganisms could decrease application of chemical fertilizers due to increasing P absorption from phosphate rock and insoluble forms of P in the soil.

Tuberose is one of the most important cut-flowers in Iran and the world. Since nutrition is an important factor in growth and quality of ornamental plants، a factorial experiment was conducted، based on completely randomized blocks design، with 12 treatments and 3 replications، in Zanjan province، in 2011، to assess the effects of nitrogen (N) fertilizer and phosphate solubilizing bacteria (PSB) on growth and quantitative traits of tuberose (Polianthes tuberose L.). N from urea fertilizer source at 4 levels (0، 50، 100 and 200 kg/ha) and PSB at 3 levels (0، 5 and 10 kg/ha microbial fertilizer) were applied to soil. Soil was inoculated with PSB before planting and N was applied in two splits (after emergence of the bulbs and 20 days after the first application). In this experiment، the plant height، length of florescence، stem and floret diameter، number of leaves and florets، and fresh and dry weights of aerial parts and roots were measured. The results of ANOVA of data showed that application of N fertilizer increased significantly all measured traits، except stem and floret diameters. All growth parameters، except dry weight of aerial parts، were increased significantly by soil inoculation with PSB. Based on the results of this study، application of 200 kg/ha N and 10 kg/ha microbial fertilizer containing PSB resulted in the highest yield and quantitative traits for tuberose.

The chemical conditions of the rhizosphere are known to considerably differ from those of the bulk soil، as a consequence of a range of processes that are induced either directly by the activity of plant roots or by the activity of rhizosphere microflora. Plant species have involved various adaptive strategies to acquire P from soil pools. Therefore، the objective of this research was to evaluate the rhizospheric effects of wheat (Triticum aestivum L.) on phosphorus availability and biological properties in 10 calcareous soils under rhizobox conditions. Thus، wheat plant was planted in rhizoboxes as a completely randomized design with three replications. After the harvest، rhizoboxes were dismantled، and dissolved organic carbon (DOC)، microbial biomass carbon (MBC)، microbial biomass phosphorus (MBP) and metabolic quotient (qCO2) were determined in the rhizosphere and bulk soils. Also، available phosphorus was measured by chemical extractants methods including Olsen، Mehlich І، Bray ІІ and calcium chloride. The results showed that DOC، MBC and MBP were strongly increased and qCO2 was strongly decreased in the most rhizosphere soils as compared with the bulk soils. Also، the amount of P extracted with different methods was lower in the rhizosphere soils as compared with the bulk soils. The correlation studies showed that dry yield and P uptake of wheat have positive relationship with extracted P by Olsen، CaCl2، Mehlich І and Bray ІІ methods and microbial biomass P in both the rhizosphere and bulk soils. The results of this research showed that Olsen، CaCl2، Mehlich І and Bray ІІ extractants could be used to estimate wheat-available P in the studied calcareous soils. Also، microbial biomass P could be used to estimate wheat-available P in the studied calcareous soils.

Rhizosphere is a micro zone with profoundly different microbiological and chemical properties compared to the bulk soil، where availability and fractionation of zinc (Zn) may also vary from the bulk soil. This greenhouse research was performed to study the available Zn and its fractions in the bean rhizosphere and bulk soils of 10 calcareous soils using rhizobox. Total organic carbon (TOC)، dissolved organic carbon (DOC)، microbial biomass carbon (MBC)، pH and available Zn using 7 chemical extraction procedures and Zn-fractions were determined in the rhizosphere and bulk soils. The results indicated that in the bean rhizosphere soils، TOC، DOC and MBC increased significantly (P<0. 01) and pH decreased significantly (P<0. 01). Extracted Zn using several chemical extractants (except Mehlich 1 and HCl) in the rhizosphere was significantly (p<0. 05) lower than the bulk soils. Also، concentrations of Zn-fractions in the rhizosphere were significantly (p<0. 05) lower than the concentrations of Zn-fractions in the bulk soils. Results indicated that significant correlation coefficients between bean indices and extracted Zn using different extractants in the rhizosphere soils were more than the bulk soils. Significant correlation (p<0. 05) was found between concentration and uptake of Zn in bean with exchangeable Zn and Zn associated with Fe and Mn in the rhizosphere soils، and with Zn associated with Fe and Mn in the bulk soils. The results of this research illustrated that availability of Zn in the rhizosphere soils are different from the bulk soils. Therefore، using rhizosphere soil would be recommended in the study of available Zn after planting.

A greenhouse experiment was conducted in order to evaluate the influence of different nitrogen (N) and zinc (Zn) levels on yield، yield components، seed quality and N and Zn contents of two cultivars of rapeseed (Brassica napus L.). In this study، two cultivars of rapeseed (Talayeh and Opera)، three N levels (100، 200 and 300 mg/kg) and three Zn levels (0، 5 and 10 mg/kg) with three replications were used. The results showed that significant differences were observed between the cultivars in the studied traits. Increasing N and Zn significantly increased plant height، number of siliques per plant، number of seeds per silique، 1000-seed weights، seed yield، oil، straw and root yields and protein content. Oil seed content was the highest in application of 100 mg/kg N rate and then decreased or increased at higher N and Zn rates، respectively. The highest grain yield، oil yield and protein percentage were obtained with 300 mg/kg N and 10 mg/kg Zn. Increase in seed yield was related to increase in the number of siliques per plant and number of seeds per silique. Application of treatments increased concentration of N and Zn in the seeds، straw، and roots of both rapeseed cultivars. The interaction of N and Zn showed significant effects on most studied traits of rapeseed.

Many efforts have been taken to increase the vase-life of cut flowers by using different methods and materials. In this research، the effect of applying citric acid and salicylic acid at pre-harvest stage on vase-life of rose (Rosa hybrida L. cv. Avalanch) was investigated. The factorial experiment was carried out as a randomized complete blocks design. Three levels of citric acid concentration (0، 2 and 4 mM) and salicylic acid (0، 1 and 2 mM) were applied as foliar spray at 5 pre-harvest stages on the leaves of roses grown under controlled conditions in greenhouse. The results showed that salicylic acid and citric acid increased longevity، water absorption، flower diameter and flower quality and delayed the effective weight loss of fresh rose flower. Maximum vase-life (with an average of 9 days) was achieved by combined foliar application of 4 mM citric acid and 1 mM salicylic acid. Also، the minimum vase-life (with an average of 7. 3 days) was obtained at the 2 mM salicylic acid treatment. The higher vase-life of rose flower was accompanied with greater fresh weight and more water absorption.

Soilless culture (hydroponic) and timely supply of plants’ essential nutrients will increase their quantitative and qualitative performance. To assess the impact of N، K and Mg on yield and fruit quality of strawberry (Fragaria×ananasa cv. Sun Rise) an experiment was performed which included control treatment (no fertilizer application)، two levels of urea (100 and 200 mg/L per pot)، two levels of potassium chloride (75 and 150 mg/L per pot) and two levels of magnesium sulfate (50 and 100 mg/L per pot)، as a randomized complete blocks design with five replications، in the controlled greenhouse conditions، as hydroponic culture، in cocopeat+ perlite (50:50 v/v) substrate. Traits such as number of florescence، number of flowers، number of fruits، fruit weight، titrable acidity، soluble solids concentration، fruit firmness، fruit yield and total anthocyanin of the fruit were measured. The results showed that high level of magnesium sulfate significantly increased number of florescence، flowers and fruits. Application of low level of urea increased fruit weight significantly. Low level of potassium chloride increased significantly the concentration of soluble solids and fruit firmness، and high level of potassium chloride increased total anthocyanin of the fruits. None of the treatments had significant effect on titrable acidity of the strawberry.

One of the important points for successful production in soilless culture system is the right fertilization timing during plant growing period for each substrate. In this respect، a factorial experiment based on completely randomized design with five replications was conducted at Sari University of Agricultural Sciences and Natural Resources. Treatments were four chemical fertilization timings (no fertilizer، fall، spring and fall + spring)، three levels of vermicompost (10، 20 and 40% v/v)، three levels of cattle manure (10، 20 and 40% v/v) and control medium (50% cocopeat: 50% perlite). The results showed that the highest strawberry yield (142. 2 g per plant) was obtained in growth medium containing 10% cattle manure with fall + spring fertilization. Moreover، the growth medium supplemented with 10% cattle manure and fall + spring fertilization produced the highest marketable fruits (10 fruits per plant) and the highest total number of fruits (18 fruits per plant). Therefore، the growth medium containing 10% cattle manure along with fall + spring fertilization provided the most suitable conditions for strawberry cultivation.