فصلنامه تحقیقات غلات
سال نهم شماره 4 (زمستان 1398)

To investigate the effect of osmotic stress induced by polyethylene glycol 6000 on seed germination components and identifying drought tolerant and susceptible genotypes, 21 rice genotypes were studied at three levels of osmotic stress (0, -7.5 and -15 MPa) with factorial arrangement in a completely randomized design with three replications. The results indicate that there were significant differences among genotypes in different levels of osmotic stress for all studied traits including radicle length, shoot length, radicle to shoot length ratio, radicle fresh weight, radicle dry weight, shoot fresh weight and shoot dry weight. The effect of genotype and genotype osmotic stress interaction were significant in all studied components. Based on measured traits, the genotypes IR28 and Line 416 were selected as susceptible and tolerant genotypes to osmotic stress, respectively. After RNA extraction and cDNA synthesis, the expression pattern of four drought responsive genes (SOD, FNR, APX and NDH) in two genotypes, IR28 and 416, at seedling stage under treatments of 0, 4, 8, 10 and 24 hours of the dehydration stress were studied using real time PCR technique. The results of this study showed that drought responsive genes had higher expression in the tolerant Line 416 than the sensitive genotype IR28 and the expression of all genes except FNR increased with increasing osmotic stress. Also, APX gene didn’t show the significant expression in either genotype, but showed the highest expression at 24 hours after stress in the sensitive genotype IR28.

Salinity is one of the limiting factors in many crops including rice production. The objective of this study was to investigate the response of 89 recombinant inbred lines derived from a cross between two Iranian rice cultivars, Tarom-Mahalli (indica) and Khazar (indica), under non-stress and 8 dS.m-1 salinity stress at vegetative stage conditions. The experiment was carried out as pod experiment under open air conditions in a completely randomized design with four replications. The results of combined analysis of variance under non-stress and salinity stress conditions showed that the the effect of line and line×stress interaction for all the studied traits was significant, indicating different reaction of the lines under two conditions. The results of simple analysis of variance also showed that the difference between lines in both conditions was significant for all traits at 1% probability level. Correlation coefficients among traits indicated that the highest correlation coefficient was observed between biomass and stem dry weight under both conditions. Stepwise regression analysis for biomass under non-stress conditions showed that root length, root to shoot dry weight ratio, number of tillers per plant at 120 th day and plant height at 120th day were the most important traits influencing biomass, respectively, while under salinity stress conditions, root area and root volume in addition to these four traits, were also identified as effective traits on biomass. Factor analysis also showed that three and five independent factors explained the correlation between biomass and the other traits in the studied lines under non-stress and salinity stress conditions, respectively. Cluster analysis using Ward’s minimum variance method under non-stress conditions divided the lines into four groups which the fourth group was consisted the lines with higher values than total average for most traits. Under salinity conditions, the lines were divided into three groups and the lines into first group had the highest biomass and the lowest genotypic score and were tolerant to salinity stress. In total, the results of current study showed that the lines 6, 9, 13, 14, 17, 18, 23, 24, 34, 39, 44, 45, 68, 79 and 80 had the higher values for most the studied traits than the other lines, in addition to higher biomass, and could therefore be considered as salinity tolerant lines in future researchs.

To evaluate the efficacy of bispyribac sodium SC42% herbicide (Rissin) on rice weeds control in transplanting method and comparing it with some registered herbicides, an experiment was carried out in two regions, Guilan (Rasht) and Mazandaran (Sari), Iran, in 2019. Treatments consisted as bispyribac sodium SC42% at four doses (50, 54, 58 and 62 ml.ha-1), bispyribac sodium OF10% at 250 ml.ha-1, bispyribac sodium SC40% at 65 ml.ha-1, oxadiargyl EC30% at 3.5 L.ha-1, triafamon + ethoxysulfuron WG30% at 150 g.ha-1, pertilachlor EC50% at 2  L.ha-1, together with two check treatments (weed free and unweeded treatment). The experiment was performed in randomized complete block design with three replications. The results showed that Rissin had good efficacy on weed control and did not cause rice damage even at the highest used dose. The efficacy of Rissin for weed control at three doses of 54, 58 and 62 ml.ha-1 was 85-91% for barnyardgrass (Echinochloa crus galli L.), 66-90% for nutsedges (Cyperus difformis L.) and 95-97% for crowngrass (Paspalum distichum L.) in Sari and 60-93% for barnyardgrass, 60-100% for nutsedges and 30-77% for crowngrass in Rasht. Weed biomass in the experimental field in Sari was lower than in Rasht, which explains the reason of the different control results. Rissin at the three higher doses had similar efficacy to commercial doses of the registered herbicides for weed control and in term of rice yield components (such as tiller and panicle number, biological yield and grain yield), the best result was obtained at 62 ml.ha-1 of Ressin and was similar to weed free treatment.

Heavy metal associated (HMA) proteins are involved in zinc (Zn) uptake from soil and its transport in plants. To study the expression pattern of HMA1, HMA2 and HMA9 genes in Zn-efficient and Zn-inefficient bread wheat cultivars under zinc deficiency conditions, a factorial experiment in completely randomized design (CRD) with three replications was carried out in greenhouse. Two Zn-efficient (Hamoon) and -inefficient (Hirmand) cultivars were grown under Zn deficient and sufficient (5 mg Zn per kg soil) conditions and relative expression of the studied genes in root and leaf at two growth stages, one month after cultivation (vegetative stage) and 30 % flowering (reproductive stage) were measured by real time PCR technique. The results revealed that the highest increase in the expression of HMA1 (30.9 fold more than check) and HMA2 (13.65 fold more than check) genes were observed at reproductive stage in the leaf and root of Hamoon cultivar under Zn deficiency conditions, respectively. In contrast, the highest increase in the expression of HMA9 gene (48.83 fold more than check) was found in the root of Hamoon cultivar at vegetative stage. Also, there was not a significant difference between Zn-efficient and -inefficient cultivars in term of expression of this gene in the root at reproductive stage. In conclusion, the results of the current study showed that the expression of HMA1, HMA2 and HMA9 genes are involved in soil Zn deficiency tolerance in Zn-efficient bread wheat cultivars.

To identify markers associated with drought tolerance related traits under two different moisture conditions including rainfed (drought stress) and supplementary irrigation, an experiment was conducted in two consecutive years (2013-2015). Among the AFLP primers used in this study, eight EcoRI/MseI primer combinations produced a total of 119 polymorphic bands with an average of 14.88 bands per marker. The average polymorphic information content (PIC) for all markers was calculated 0.298. Based on PIC, Shannon's index (I), expected heterozygosity (He) and effective allele (EA), the combination of E-ACT/M-CTT was identified as the best primer combination in distinguish of the studied genotypes. The relationship between agro-physiological traits as dependent variables and molecular data as independent variables was investigated using stepwise multiple regression analysis method and 76 and 98 markers associated with traits were identified under rainfed and supplementary irrigation conditions, respectively. Under supplementary irrigation conditions, the highest coefficient of determination (R2) was allocated for E-ACT/M-CTC-11 marker with more than 60% explanation of variations in peduncle weight, peduncle length, spike dry weight and grain weight per spike and E-ACT/M-CTT-8 with explanation of 62% variation of 1000 grain weight. Under rainfed conditions, the markers E-ACT/M-CTT-8 with 70%, E-ACG/M-CTG-2 with 57% and E-ACG/M-CAA-2 with 51%, explained the highest variation of 1000 grain weight, relative water lose and relative water content, respectively. The markers E-ACT/M-CTC-11 and E-ACG/M-CAA-20 explained 32% and 41% of the grain yield variance under supplemental irrigation and rainfed conditions, respectively. In this study, the marker E-ACT/M-CTT-8 explained more than 60% of the variation in 1000 grain weight under both experimental conditions. The results of this study can be useful in providing basic information for indirect selection of wheat traits using associated markers under rainfed conditions.

To evaluate the role of different levels of exploitation on economic and energy indices of irrigated wheat production in Dehloran city, Ilam province, Iran, this study was conducted and the farms with areas of 1-5, 5-10 and 10-15 ha were surveyed. The sampling method was simple classification and the energy indices including energy ratio, energy efficiency, energy intensity and net energy as well as the economic indices including production cost, gross production value, net income and profit to cost ratio were evaluated. Data analysis of variance and the economic calculations was performed usin SPSS and Excel softwares, respectively. The results of analysis of variance showed that there was a significant difference between the treatments at the 1% probability level in term of energy and economic indices. Evaluating the energy indices indicated that for farms with an area of 1-5, 5-10 and 10-15 ha, the energy ratio index was 4.12, 5.20 and 5.77, respectively, while the energy productivity was determined 0.17, 0.21 and 0.23 kg.MJ-1 and the energy intensity was 5.98, 4.81 and 4.44 MJ.kg-1, respectively. The proportion of renewable energies from the total input energy for the studied areas of 1-5, 5-10 and 10-15 ha was stimated to be 17%, 18% and 19% and the proportion of non-renewable energies was 83%, 82% and 81% , respectively. The profit to cost ratio was also evaluated to be 2.16, 2.60 and 2.95, respectively. The results of this study showed that with increasing cultivation area, energy ratio, energy productivity and profit to cost ratio increased and energy intensity and production cost per ha decreased. The best treatment was also determined 10-15 ha. Therefore, it seems that the development and implementation of necessary programs for land consolidation will improve the energy and economic indices and increase the efficiency and productivity in agriculture.

After nitrogen, phosphorus is the most important and essential nutrient for plants, and plays the most important role in the process of energy production and transmission. In this sttudy, the efficiency of phosphorus adsorption and consumption in 93 maize inbred lines were assessed based on a potted experiment in a completely randomized design with three replications under phosphorus sufficient (optimum) and deficient conditions. The results of analysis of variance revealed that there was a significant difference among maize lines in terms of shoot dry weight, total phosphorus content and concentration, fertilizer response index, phosphorus adsorption efficiency index, phosphorus consumption efficiency index and calculated phosphorus efficiency index. The fertilizer response index of maize lines varied from 13 to 223.67 g with an average of 70.39 g. The phosphorus adsorption efficiency index in the studied lines ranged from 0.11 to 0.85 and its average was 0.41 mg/kg. The phosphorus consumption efficiency index varied from 1.10 to 4.65 g dry matter per mg phosphorus and its average under sufficient (optimum) and deficient conditions were calculated 0.97 and 1.89 g, respectively. The phosphorus efficiency index ranged from 0.40% to 0.95% with an average of 0.71%. Based on the evaluated indices under soil phosphorus deficiency conditions, the maize lines 1, 9, 10, and 26 are introduced as phosphorus-efficient genotypes and the lines 65, 46, 49 and 79 as phosphorus-inefficient genotypes. The phosphorous-efficient lines introduced in this research can be potentially used to produce phosphorus-efficient maize varieties in the future breeding programs.