فصلنامه تحقیقات غلات
سال سوم شماره 3 (پاییز 1392)

To investigate salinity tolerance at seedling stage, seventeen landrace and improved genotypes of rice (Oryza sativa L.) were assessed in a factorial experiment based on randomized complete block design with three replicates. Four salinity levels (1.19, 4, 8 and 12 ds.m-1) was applied in the early stage of vegetative growth. Results showed that the genotypes were significantly different for salinity tolerance score. Morphological characteristics such as stem (SL) and root (RL) length, dry weight of stem (SDW) and root (RDW), root to shoot length (RL/SL) ratio and vegetative biomass (Bi) were measured. Significant differences (P< 0.01) among genotypes were observed on all studied traits, indicating genetic variation among the genotypes. Mean comparisons among genotypes showed that root and shoot length decreased with increasing salinity levels. The highest and lowest shoot length belonged to Shahpasand and Hasansaraei varieties, respectively. Salinity tolerance indices showed that the highest value of STI, MP, GMP and HM belonged to Shahpasand, Sangjo and Line 4. Results of correlation coefficients among the indices and principle component analysis showed that STI, GMP and HM indices were the most suitable resistance indices. Also, results of principle component analysis and cluster analysis for clustering the studied genotypes by using of these indices exhibited that Shahpasand and Line 416 were most tolerant to salinity stress at seedling stage among the studied genotypes.

Plant lodging is one of the major problems that may occur depending on the time to 50 reduction in yield of rice crop. Identification of plant characteristics related to lodging resistance considered as the prerequisite for reduction of losses in rice cultivation. In order to evaluate the morphological characteristics and lodging related traits in native and improved rice cultivars, a field experiment was laid out in randomized complete block design with three replications in 2012 at the Rice Research Institute of Iran, Rasht. Rice genotypes including three native rice cultivars (Hashemi, Sangjo and Alikazemi) and three improved (Kadous, Gohar and Khazar). Results showed correlation between thickness of internode whit breaking resistance of third internode (r=0.914**) and thickness of fourth internode whit breaking resistance of fourth internode (r=0.846**), thickness of third and fourth internode whit pushing resistance (r= 0.935** and r= 0.926**, respectively). Also significant positive correlation between fresh weight/length of internode whit breaking resistance in third internode (r= 0.967**) and pushing resistance (r= 0.870**), fresh weight/length of internode whit breaking resistance in fourth internode (r= 0.922**) and pushing resistance (r= 0.835**) were observed. Stepwise regression analysis showed that thickness of internode was the lone trait that significantly affected the pushing resistance. fresh weight/length of internode and dry weight/length of internode had highly significant effect on breaking resistance that was in correspondence with the results of correlation analysis. It seems that the thickness and weight/length of internode, have major roles in rice plant resistance to lodging and could be considered as indirect indices in selection for higher resistant rice cultivars.

Yellow (stripe) rust caused by Puccinia striiformis f. sp. tritici is one of the most damaging diseases of wheat in Iran. Host resistance, especially race- nonspecific resistance, is the most economical way to manage wheat stripe rust. Although the life of effective race –specific resistance genes can be prolonged by using gene combinations, an alternative approach is to deploy varieties that possess race- nonspecific resistance based on combinations minor, slow rusting genes. In order to evaluate race-nonspecific resistance, seedling and adult plant reactions of 22 promising wheat lines along with susceptible check were evaluated to yellow rust. The seedling reaction was evaluated in greenhouse by using race 6E150A+, Yr27. Adult plant resistance was also evaluated by measuring of final rust severity (FRS) and coefficient of infection (CI) under natural infection conditions with two times artificial inoculations. Artificial inoculation was carried out by yellow rust inoculum having virulent genes against Yr2, Yr6, Yr7, Yr9, Yr22, Yr23, Yr24, Yr25, Yr26, Yr27, YrA, and YrSU. Field evaluation was conducted based on randomized complete block design with three replications during 2011-2012 cropping season at Ardabil Agricultural Research Station (Iran). Results showed that lines S-90-1, S-90-14, S-90-16, S-90-17, S-90-20, S-90-21 and S-90-22 along with susceptible check (Bolani) had the highest values of FRS and CI. The lines S-90-2, S-90-3, S-90-4, S-90-9, S 90-11, S- 90-13 and S-90-18 were susceptible at the seedling stage and had low values of FRS and CI at the adult plant stage. Consequently, these lines have different levels of slow rusting resistance (racenonspecific or durable resistance) based on the results of this investigation and their pedigree information. The remaining lines that had low level infection at the seedling and adult plant stages were selected as moderately resistant or resistant lines.

To study the response of yield and yield components of wheat to mycorrhiza and mycorrhiza-like fungi at different levels of organic matters and to determine the relationship between the effective characteristics on yield, a pot experiment was conducted in 2010, at Dryland Agricultural Research Institute using randomized completely design with four replications. Treatments were considered organic matter from spent mushroom compost at three levels (0, 25 and 50 Mg ha-1) and fungi symbiosis in four levels [non-inoculation mycorrhiza (Glomus mosseae), mycorrhiza-like (Piriformospora indica) and co-inoculation of two fungi]. The measured characteristics included plant yield, yield components and characteristics such as peduncle length, extrusion length, plant height and spike length. Results indicated that compost had a positive and significant effect in all studied characteristics except 1000-grain weight. Although P. indica in low levels and Glomus mosseae in moderate and high levels of organic matter produced more grain and biological yield, overall, coinoculation of two fungi showed the best performance. Stepwise regression and path analysis were conducted separately for each levels of organic matter. The results indicated that grain number per plant and 1000-grain weight in the without compost treatment, biologic yield, harvest index and spikelet fertility percentage in the 25 Mg ha-1 of compost and biologic yield and harvest index in the 50 Mg ha-1 of compost were entered in the final model. In general, grain number per plant in without compost and biological yield in 25 and 50 Mg ha-1 of compost had the most direct effect on grain yield.

Heavy metals particularly cadmium (Cd) enter in food chain through soil and plants. Therefore, determining spatial variability of Cd concentration in soil and crops is important to manage adverse effects of Cd on environment. This research was conducted to assess the spatial variability of soil and wheat grain Cd in large farms. A number of 255 farms in Khuzestan province (355000 ha) at wheat maturity stage were sampled, using an irregular weighting sampling scheme. In each region, the density of samples was chosen according to the area and spatial distribution of the wheat farms. Pair compound soil (0-20 cm) and grain samples were taken from each wheat farm. The Cd concentrations in soil (total and DTPA-extractable) and grain samples were then measured. Also, the spatial variability of soil and grain Cd were obtained by normal Kriging method. The results indicated that the total Cd concentrations in 95 percent of samples exceed 0.8 mg kg-1. However, the DTPA-Cd concentrations in 25 percent of soil samples were more than 0.1 mg kg-1. In addition, grain Cd concentrations in 95 percent of the samples were exceeded the threshold of 0.2 mg kg 1 grain. The semivariograms of soil (total and DTPA-extractable) and grain Cd were well fitted with a spherical model. The spatial distribution of total Cd using normal Kriging, revealed two most contaminated zones, one at south and the other at west. Also, for DTPA-Cd, the east and south were the most contaminated regions in the study area. The spatial distribution of grain Cd indicated high Cd concentrations at the east, west and some parts of south area.

To evaluate the reaction of some sweet corn varieties to new urea sulfonyl and mixture herbicides, an experimental research based on a randomized complete block factorial design with three replications was conducted. The first and second factor were sweet corn variety and chemical control included nicosulfuron (Cruz), nicosulfuron (Cruz) + bromoxinyl+MCPA (brimicide MA), foramsulfuron (equip), Rimsulfuron + Nicosulfuron (Ultima), Mesotrion+ S-Metolacholor+ Terbuthlazine (Lumax 537.5 SE), with three cultivars of sweet corn including golden (KS 403su), Merit and Chase, weed free, weed infested with three replication in each block. Assessment rate included injury sweet corn on EWRC, sweet corn varieties and weeds biomass at 4 weeks after spraying. Merit variety was ruined by nicosulfuron, nicosulfuron+ bromoxinyl+MCPA, rimsulfuron and foramsulfuron + nicosulfuron application as susceptible cultivar, and Golden and Chase with minimum injury by these herbicides usage known as tolerance varieties. Mesotrion+ S Metolacholor+ Terbuthlazine was only herbicide which applicable on Merit variety. The herbicides effect was significant on stem diameter, leaf number, plant dry weight, plant height, ear length, ear diameter, cob weight and grain weight per ear. The highest and lowest grain yield related to Chase and Merit varieties, respectively. Golden variety had medium grain yield between two varieties. Also, the result showed that red root pigweed, common purslane, binweed, common lambsquarter, purple nutsedge, black nightshad density and dry weight reduced by all of the herbicides compared control treatment, significantly. Totally, Mesotrion+ S-Metolacholor+ Terbuthlazine were only herbicide that applicable in all of sweet corn varieties without any injury to crop and high effect to all weeds control.

To evaluate and select the best system of rice production among traditional, semi mechanized and mechanized systems, in Guilan province, the Analytical Hierarchy Process (AHP) was used. Hence the data obtained in 2012 from 25 agricultural experts and 18 pioneer farmers was used for analysis. For this method of evaluation, five main criteria considered were 1- Agronomic criteria 2- Energy criteria 3 - Economic criteria 4 - Social criteria 5- Ergonomic criteria (pollution and ease of cultivation). This technique determined and ranked the importance of criteria affecting on selection of best rice production system based on attributing relative weights to factors with respect to comments provided in the questionnaires. By using of software (Expert Choice) Analytical Hierarchy Process was done. The result of this survey by AHP techniques showed that Ergonomic criteria had the most and Energy criteria had the least importance for expert and farmer in rice production section. Between rice production systems, the mechanized system to 0.347 weighted average was the best rice production system and semi-mechanized system to 0.329 weighted average and traditional system to 0.324 weighted average was later respectively. However the result of AHP techniques showed that the mechanized system based on Social criteria was weak. It shows that rice production in the province of Guilan need to Authorities try for better management and if possible to establish cultural appropriate to increase the use of mechanized system be considered.