فصلنامه تحقیقات غلات
سال ششم شماره 1 (بهار 1395)

The GGE (genotype main effect¡ G and genotype by environment interaction¡ GEI) biplot graphical tool was applied to analyze multi-environment trials (MET) data. In this study¡ eight improved and local rice genotypes including two rice cultivars as check were evaluated with the objective of selecting stable and high-yielding varieties by GGE biplot analysis. According to which-won-where pattern of GGE biplot the vertex genotypes were BC25¡ BC4¡ RI18446-13¡ Hassani¡ Abjiboji and RI18435-13. These genotypes were the best or the poorest genotypes in some or all of the test environments since they had the longest distance from the origin of the biplot. The performance of genotypes BC9¡ BC25¡ RI18436-46 and Saleh were highly stable and had the highest grain yield¡ while genotype BC4 was high yielding with intermediate stability. In addition¡ performance of genotype RI18446-13 was lowly stable with the high grain yield and genotype RI18435-13 was poor based on both stability and yield. But the performance of genotype Hassani was intermediate stable with low grain yield¡ while genotypes Abjiboji and RI18430-74 were highly stable with low yielding. Totally¡ the results of this research showed that BC4 line (derived from a backcross between Abjiboji cultivar as recurrent parent and Saleh cultivar as donor parent) with high grain yield (5.0-5.5 t.ha-1)¡ suitable maturity time (110-115 days)¡ intermediate amylose content (20-21 %) and desirable plant height (105-110 cm) was the superior genotype of this experiment which is recommended to cultivate in environmental conditions of the north provinces of Iran.

In this research, the expression of glutathione peroxidase (OsGpx) and proxy redoxin (OsPrx), H2O2 and Guaiacol dependent peroxidase (POD) content was measured in Iranian local (Hassani and Anbarboo) and improved (Nemat and Khazar) rice varieties with two well-known international salt tolerant (FL 478) and sensitive (IR29) varieties as checks in response to 100 mM salt stress. The results showed that the activity of peroxidase (POD) was different at different times in the studied cultivars, so that the enzyme activity in resistant cultivars was higher than susceptible ones under salt stress. Gene expression of glutathione peroxidase (OsGpx) showed the highest expression of this gene in the roots of tolerant varieties 6 hours after the stress treatment and then 12, 24, 48 and 72 hours after the stress the expression of this gene significantly decreased. In susceptible cultivars, gene expression increased gradually. The study of peroxy-redoxin (OsPrx) gene expression showed that in the first hours after the stress, tolerant varieties did not show any change in this gene expression, but in the final hours of stress (72 hours) gene expression was significantly increased. There was no consistent pattern for this gene in susceptible cultivars. The results showed there was a direct relationship between the reduction of H2O2 and increased activity of antioxidant genes and enzymes.

To evaluate and compare different rice genotypes under salinity conditions, two separate experiments under two salinity and non-salinity fields were conducted in randomized complete block design with three replications in west of Guilan province (Astara) during 2009-2010. Results of the analysis of variance showed that there were significant differences between the salinity conditions, varieties and variety × stress interaction effect for grain yield at the 1% probability level. Mean comparison of the total grain yield indicated that the varieties Gharib-Siahreihani and Hashemi had the highest and IR29 the lowest grain yield. Mean comparison of variety × salinity interaction effect showed that the highest grain yield under non-salinity condition belonged to Gharib-Siahreihani and Hasansaraei-Atashgah while under salinity condition, Hashemi produced higher grain yield. In contrast, the lower grain yield under both stress and non-stress conditions belonged to IR29 variety. Hashemi variety had the higher stress tolerance index than the other varieties. Principal component analysis based on grain yield and stress tolerance and susceptibility indices identified two principal components with eigen values greater than one explaining 99.9 % of the total variance in the studied population. Distribution of the studied cultivars based on biplot of the grain yield and these indices presented Hashemi, Tarom-Amiri, Tarom-Pakotah and Garib-Siahreihani as tolerant varieties and IR29 as sensitive variety to salinity stress. Tolerant varieties are recommended to improve salinity tolerance in the rice breeding programs.

Rice is one of the major staple foods for more than half of the world population. The effect of three rice cultivation systems and foliar application of two zinc fertilizers was investigated on yield, yield components and water consumption of rice cv. ‘Sazandegi’ in Isfahan Agricultural Research Center, Isfahan, Iran, during 2013. This experiment was carried out in split plots using randomized complete block design with three replications. Three cultivation systems including system of rice intensification (SRI), conventional rice cultivation system (CRC) and improved rice cultivation system (IRC) were considered as the main factor and four zinc foliar applications including 150 and 300 mg.L-1 nano-ZnO and 3 and 6 g.L-1 SO4Zn together with foliar application with distilled water and no-foliar application (as first and second checks, respectively) were applied as the sub-factor. The results showed that highest grain yield (9451 kg.ha-1) obtained from SRI which was 10% and 13% higher than CRC and IRC, respectively. Foliar application with both zinc fertilizers significantly increased grain yield so that nano-zinc oxide (150 mg.L-1) and zinc sulfate (6 g.L-1) produced 5% and 5.7% more grain yield than the both checks, respectively. Minimum water consumption obtained from SRI which was 17.5% and 18.2% lower than CRC and IRC systems, respectively. On the basis of the results of this research, SRI system and foliar application of zinc sulfate (6 g.L-1) or nano-zinc oxide (150 mg.L-1) is recommended.

Line × tester analysis is one of the biometrical methods for genetic analysis of quantitative traits to determine combining ability of the parents and heritability of the traits and identify the best breeding method for the studied population. In this study, three rice cultivars Hashemi, Nemat and Jelodar as the parental lines with two cultivars Sange-Jo and Deylamani as the maternal lines (tester) were crossed. The progenies and their parents (a total of 11 treatments including five parents and six progenies) were studied in a randomized complete block design with four replications in next year and plant height, tiller number, panicle length, grain number per panicle, 1000-grain weight, grain yield, grain length, grain width and grain length to width ratio were measured. Analysis of variance showed significant differences among genotypes for all of the studied traits. Evaluation of general combining ability of the parents showed that Hashemi was the good general combiner for reduction of plant height, but it also had the significant and negative combining ability for yield components including tiller number, panicle length, grain number per panicle and 1000-grain weight which lead to reduction of progeny values. Nemat had the significant and positive combining ability for all of the studied traits and was the best general combiner for tiller number, grain number per panicle and grain length. Jelodar variety was also the best general combiner for increasing panicle length and 1000-grain weight as well as reduction of grain width. Investigation of the specific combining ability of the crosses indicated that except Nemat × Sange-Jo and Nemat × Deylamani which had the significant specific combining ability for increase and decrease grain length, respectively, specific combining ability of the other crosses was not significant. Evaluation of genetic variance components showed that the additive variance had important and main role in all of the studied traits, except for grain length which the proportion of non-additive variance was more than the additive variance. It seems that the hybrid production method could be better to improve grain length in the studied population, but for other traits the selection methods will be useful.

In the present study, allelic diversity of low-molecular-weight glutenin genes was analyzed in 193 Iranian winter wheat landraces and Thatcher cultivar. Using Glu3A.2 primer pair, eight fragments with size of 315-358 bp were amplified so the fragment of 342 bp with 37.2% and the fragment of 315 bp with 0.6% showed maximum and minimum frequency, respectively. Based on Glu3A.3 primer pair, five fragments with range of 638-754 bp were amplified which the fragment of 700 bp and 742 bp with 92.1% and 0.6% showed maximum and minimum frequency, respectively. Two fragments 440 bp with frequency of 74.6% and 421 bp with frequency of 25.4% were amplified using Glu3B.2 primer pair. Glu3D.2 primer pair amplified three fragments with size of 571, 558 and 382 bp and frequency of 1.7%, 88.1% and 10.2%, respectively. Six fragments with ranging from 589 to 611 bp with frequency of 1.2-27.9% were produced using Glu3D.3 primer pair. Glu3D.4 primer pair amplified only one fragment of 700 bp in the Iranian winter wheat landraces. The PIC value ranged from 0.15 to 0.75 with an average of 0.24 and the gene diversity or expected heterozygosity varied from 0.15 to 0.78 with an average value of 0.26. Cluster analysis based on molecular data using No. of difference distance coefficient and Neighbor-Joining algorithm assigned the Iranian winter wheat varieties into two groups. Analysis of molecular variance (AMOVA) based on climatic conditions (five climatic conditions cold, mountainous,temperate, warm and dry) revealed higher within group variation (94%) compared to between group. The result of this study showed that Iranian wheat landraces could be used as valuable genetic resources in breeding programs to improve bread making quality of wheat.

To evaluate nitrogen uptake, nitrogen uptake efficiency, nitrogen use efficiency and nitrogen harvest index of wheat (Triticum aestivum L.) affected by different tillage systems and wheat residue application, an experiment was conducted as a split block experiment in a randomized complete block design with three replications at Ferdowsi University of Mashhad, Iran, during 2013-2014 growing season. Four different tillage systems (disk, mouldboard plough disk, sweep plough disk and chisel plough disk) were considered as vertical factor and five different crop residue applications (0, 25, 50, 75 and 100% wheat residue) as horizontal factor. The results showed that lowest (2.58%) and highest (2.77%) seed nitrogen percentage were obtained from disk and chisel plough disk, respectively. Also, the highest nitrogen uptake and use efficiency (60.67% and 17.25 g seed/g soil) were obtained from chisel plough disk treatment. The results indicated that seed nitrogen percentage, nitrogen uptake and use efficiency significantly increased with increasing the levels of wheat residue, so that application of 75% wheat residue increased nitrogen uptake to 62.2% compared with control treatment. Regarding to the results of this study, it seems that application of wheat residue along with reduced tillage as an ecological approach can be recommended in arid and semi-arid regions of Iran to increase nitrogen uptake and use efficiency.

To investigate yield and yield components of wheat in response to reduced nitrogen fertilizer and seed consumption under sustainable agriculture conditions, an experiment was carried out as split plot factorial based on randomized complete block design with four replications in Dezfol Agricultural Researc Center, Dezfol, Iran, in 2011-2012. Two wheat cultivars (Chamran and Behrang) in main plots and five levels of seed density (50, 100, 150, 200 and 250 kg.ha-1) together with six levels of nitrogen fertilizer from urea source (0, 50, 100, 150, 200 and 250 kg.ha-1) as factorial in sub-plots were considered. The result of analysis of variance showed that the effects of cultivar, nitrogen fertilizer and seed density were significant on grain yield and yield components at 1% probability level. Chamran with the average grain yield of 4130.70 kg./ha-1 was significantly higher than Behrang. Seed consumption more than 100 kg.ha-1 was reduced grain yield and the highest grain yield with the average of 4975 kg.ha-1 was obtained from seed density of 100 kg.ha-1. In contrast, increasing nitrogen fertilizer up to 150 kg.ha-1 significantly increased grain yield and then there was no significant change.

To study the effects of drought stress, plant growth promoting rhizobacteria (PGPR) and humic acid on yield and yield components of durum wheat, an experiment was conducted at research field of Islamic Azad University, Yadegar-e-Imam Khomeini, Shahr-e-Rey, Iran, in 2011-2012 growth season. The experiment was carried out as split-plot factorial in randomized complete block design with four replications. The experimental factors were irrigation regimes in three levels (irrigation after 80, 120 and 160 mm evaporation from class A evaporation pan) in main plots and humic acid and plant growth promoting rhizobacteria (PGPR, Azospirillum and Azotobacter pseudomonas) both in two levels, (application and non-application) as factorial in sub-plots. The results indicated that apart from the effect of humic acid on grain number and biological yield, the main effect of other factors were significant on all evaluated traits. In this case, decreasing irrigation interval to 80 mm, increased grain yield to 3655.37 kg/ha and application of PGPR increased grain and biological yield (9.4% and 4.6% respectively). The application of humic acid also increased grain yield (6.9%) compared to non-application. Among the interaction effects, only the irrigation × PGPRs were significant on peduncle length and number of spikes per m2. In this circumstance, irrigation after 80 mm evaporation from class A evaporation pan under both inoculated and non-inoculated grains by PGPRs showed the highest amounts of mentioned traits than control. The findings of this research showed that the positive effect of PGPRs on most studied traits was more than humic acid.

To investigate the effect of drought stress and phosphorus bio-fertilizer on yield and its components of maize, SC640, a split plot experiment was conducted based on randomized complete block design with three replications in Islamic Azad University, Dezful Branch, Dezful, Iran, during summer of 2013. Three levels of drought stress including full irrigation (control), drought stress at flowering stage and drought stress at grain filling stage were assigned as main plots and two levels of bio-fertilizer (non-inoculation and inoculation with phosphorus bio-fertilizer) as sub-plots. Analysis of variance showed that drought stress was significantly influenced all of the studied traits. The effect of bio-fertilizer was also significant on all of the traits except for number of rows per ear. The interaction effect of drought stress × bio-fertilizer was significant on ear length, grain phosphorus content, grain phosphorus uptake, grain protein content, grain nitrogen uptake, nitrogen harvest index, phosphorus harvest index and hectoliter weight. The application of bio-fertilizer lead to increasing of 17% in grain yield. The highest value of grain yield (11813.3 kg.ha-1) was obtained under full irrigation condition. Drought stress at the flowering stage decreased grain yield (36%), number of grain per row (16%) and number of row per ear (8%). Although, drought stress at two growth stages significantly reduced the rate of grain nitrogen uptake and hectoliter weight under both inoculated and uninoculated conditions, but phosphorus bio-fertilizer had the modifier role on these traits under drought stress conditions. Thus, results of this research showed that inoculation of seeds with phosphorus bio-fertilizer can be reduced the harmful effects of drought stress on grain yield and quality traits of corn.