Salinity threshold value of Quinoa (Chenopodium Quinoa ‎Willd.) at ‎various growth stages and the appropriate ‎irrigation method by saline ‎water

Salinity is one of the major agricultural problems in arid and ?semi-arid regions. Considering the variation of plant’s ?sensitivity to salinity during growth, a greenhouse study with completely randomized design? was conducted to determine the relative salinity tolerance of Quinoa (Chenopodium quinoa Willd.) at different growth stages from seedling establishment to maturity (establishment, flowering and seed filling) by evaluating the Salinity Threshold Value (STV). Eight levels of EC_i (i.e., Non-saline, 2, 4, 8, 12, 15, 20, 25 dSm^?1) with four replications and five levels (i.e., Non-saline, 10, 15, 20, 25 dSm^?1) with three triplications were applied at first and two last growth stages, respectively. A ?comparison was performed on some growth and yield parameters of plants irrigated by considering STV (T) and ?plants irrigated permanently by mentioned salinity levels regardless of STV (P) to choose ?which method (P or T) is better at each salinity level. The STV was ?evaluated 8, 20 and 15 dSm^?1 at each growth stage, respectively. Seedling of Quinoa was more sensitive to salinity than the mature plant. Therefore, after establishment Quinoa has the ?feasibility of irrigation by high-saline waters. The (P) ?method was suitable only if the freshwater was available during all growth period of the plant; otherwise at higher salinities irrigation should be performed by considering STV (T method) to minimize the intensity of growth and yield reduction and to prevent yield loss at very high salinities. To achieve this, if high-saline water is available it’s possible to ?use plant propagation techniques or cultivating Quinoa simultaneously with seasonal rainfall.?     

Egyptian broomrape (Phelipanche aegyptiaca) response to silicon nutrition in tomato (Solanum lycopersicum L.)

Egyptian broomrape is a root holoparasitic plant that causes severe damage to tomato in Iran. Experiments were conducted in 2013 to investigate the effect of silicon (Si) nutrition on broomrape response in tomato. Si concentration significantly delayed first appearance of broomrape and decreased number of tubercles in both cultivars, although the magnitude of reduction varied with cultivar and Si concentration. Broomrape infection significantly decreased root and shoot dry weights of tomato cultivars. However, Si nutrition at high concentration considerably reduced damage severity of broomrape compared to the treatment that received no Si. Infection of tomato with broomrape resulted in significant increase in peroxidase and catalase activity in the roots of resistant cultivar which led to enhanced crop resistance to oxidative stress and improved growth in this cultivar.     

Least limiting water range for different soil management practices in dryland farming in Iran

Integrated evaluation of soil physical properties using the least limiting water range (LLWR) approach may allow a better knowledge of soil water availability. We determined the LLWR for four tillage practices consisted of conventional tillage (CT), reduced tillage (RT), no-tillage (NT) and fallow no-tillage (NT_f). In addition, LLWR was determined for abandoned soils (i.e. control), compacted soils, ploughed compacted soils and abandoned soils with super absorbent polymers (SAPs) application. Soil water retention, penetration resistance (PR), air-filled porosity and bulk density were determined for the 0–5 and 0–25-cm depths. Mean LLWR (0.07–0.08 cm³ cm^?3) was lower in compacted soils than the soils under CT, NT, NT_f, RT, tilled, abandoned and SAP practices but it was not different among tillage practices. The values of LLWR were 0.12 cm³ cm^?3 for NT and CT. LLWR for tilled plots (0.12 cm³ cm^?3) became greater than compacted soils by 1.3 times. Analysis of the lower and upper limits of the LLWR further indicated that PR was the only limiting factor for soil water content, but aeration was not a limiting factor. The LLWR was more dependent on soil water content at permanent wilting point and at PR.     

Genotypic Variation for Water-Deficit Tolerance in Cotton (Gossypiumhirsutum L.) Germination in Southern Iran

To determine the effect of water deficit on growth characteristics of 27 cotton cultivars (Gossypiumhirsutum L.), two separate experiments were performed in laboratory and glasshouse in Fars Province, Zarin-Dasht city (28° 36′ N, 54° 41′ E) in August 2015. In both experiments, which last for 10 days, a completely randomized block design with three replications was used. The main factor was water-deficit levels ((0, ?4, and ?12 MPa in laboratory and (0 and ?8 MPa) in glasshouse experiments), and the subsidiary factor was different cotton cultivars. The sensitivity to water deficit was compared based on factors such as germination rate, shoot and root lengths, fresh and dry weights, seed energy, and seed vigor. The results of both experiments indicated that Oltan, Opal, Pak, Armaghan, Super-Elit Golestan, Super-Elit Bakhteghan, SB-35, Super-Elit Arian, Khandagh, Tabela-18, and Sahel cultivars are more resistant and therefore are suitable candidates to increase plant density and uniformity in the farm.