وزن تر اندام هوایی

Symbiosis with arbuscular mycorrhizal (AM) fungi often increases the tolerance of host plants against various stresses. Among abiotic stresses, salinity causes considerable loss in crop productivity. Comprehensive study of plant genotypes response to symbiosis with AM fungi and potential role of this relationship in improving the adverse effects of salinity and increasing plant tolerance would be effective in increasing crop yield. The present study aimed to investigate response of commercial barley varieties to mycorrhizal colonization under salinity stress.

In this experiment, six commercial barley varieties including Khatam, Golshan, Afzal, Aras, Makoui and Dasht were evaluated at two salinity levels of NaCl (0 and 150 mM) and two symbiosis levels including inoculated and non-inoculated with Funneliformis mosseae. A factorial design in a randomized complete block design with three replications was conducted under greenhouse conditions in Zanjan University, Zanjan, Iran. Five weeks after cultivation, barley plants were harvested and the traits related to fungal structures including total colonization rate, and the frequency of hyphae, arbuscule and vesicle were measured. Also, some physiological traits including shoot fresh weight, leaf relative water content (RWC), shoot Na+ concentration, shoot K+ concentration, and Na+/K+ ratio were measured.

The results of this experiment showed that there was a significant variation between barley varieties in terms of colonization rate and hyphae, arbuscule and vesicle frequencies of AM fungus. Also, salinity stress reduced the colonization rate, and hyphae and arbuscule frequencies of the fungus, but increased the vesicle frequency, which this reduction was more considerable in salt-tolerant varieties, Khatam and Afzal, especially in Afzal. The increase in vesicle frequency was also significant only in Makoui, Aras and Dasht varieties. The results showed that salinity stress reduced shoot fresh weight and leaf relative water content, and increased Na+ concentration and Na+/K+ ratio in all barley varieties, but these changes in Makoui, Aras and Dasht varieties especially in Aras were more than other varieties. On the other hand, colonized plants exhibit lower shoot fresh weight and leaf RWC compared to non-colonized ones. However, symbiosis enhanced leaf RWC in Khatam and Golshan varieties under non-stress conditions.

The results of this study showed that there was a significant difference between barley commercial varieties in terms of response to symbiosis with mycorrhizal fungus and response to salinity stress. Although the reduction of colonization rate may help barley plants to prevent the consumption of carbohydrate resources, the expected results of symbiosis in terms of improving barley plant growth or reducing the adverse effects of salinity stress on the plant was not observed in the present study. This indicates the complexity of the symbiotic relationship between plant and fungus, and environmental conditions especially stress conditions can increase this complexity.

Lead as a heavy metal and permanent chemical contaminant threat the health of environment and alive creatures through different artificial and natural sources. In order to investigate the effect of methyl jasmonate and lead stress on growth characteristics, the adsorption and accumulation of lead and hazardous index in basil, a pot factorial experiment was carried out based on completely randomized design in research greenhouse of Ferdowsi University of Mashhad. The treatments consisted of three levels of lead nitrate (0, 200 and 400 mg/kg soil), and methyl jasmonate spraying in three concentrations (0, 0.5 and 1 mM). The mean comparison of data represented the reduction in all the studied morphological traits and increasing the amount of lead in the leave and root of the plant and hazardous index with increasing lead stress levels and spraying with methyl jasmonate could partly improve some of these traits. So that spraying with 1 mM methyl jasmonate cause to increase 6.01% inflorescence length and cause to decrease lead amount of the eave 96.56, 79.31 and 99.20%, respectively and hazardous index, however, at o.5 mM methyl jasmonate cause to increase the number of branches and aerial fresh weight, 27.66 and 9.84%, respectively. Therefore, it seems that application of methyl jasmnate on stress conditions could improve partly the traits and so in some cases 1 mM methyl jasmonate concentration cause to decrease some morphological traits. Therefore, application of o.5 mM methyl jasmonate on lead stress is recommendable.

This research was carried out with the aim of studding the effect of chelate and nanochelate of potassium foliar application on some growth and physiological characteristics of basil (Ocimum basilicum L.) under deficit irrigation stress. The study was conducted as a factorial experiment in a randomized complete block design with three replications in the greenhouse of Agriculture Faculty of Bushehr University in 2016-2017. Plants were subjected to four deficit irrigation stress levels (100, 80, 60 and 40% of field capacity moisture). Four different rates of chelate and nanochelate of potassium (0, 1, 3 and 5 g/L) were applied through foliar spray. The results indicated that deficit irrigation stress significantly (p