Cereal Research
Year:2018 | Volume:8 | Issue:2|Papers Count:10

The formation of grain yield depends on fators such as available radiation and the genetic characteristics of plant like radiation interception rate, radiation use efficiency and biomass contribution. In regard to climatic changes, for studying the effect of environmental conditions on this characteristics, a factorial experiment in randomized complete block design with three replications was conducted at Haraz Extension and Technology Development Center, Iran, in two crop seasons, 2013 and 2014. Three transplanting dates were used to encounter rice varieties under different environmental conditions. Treatments included rice cultivars (Tarom Samadi, Tarom Hashemi, Local Tarom, Shiroudi, Keshvari and Gohar) and transplanting dates (5th may, 20th may and 10th June). Results showed that grain yield, biomass, LAI at heading and 20 days after heading, harvest index, accumulated intercepted photosynthesis active radiation (PAR), radiation use efficiency, grain filling rate, grain filling period and panicle number. m2 varied significantly between rice varieties. Transplanting date had significant effect on all traits, except radiation use efficiency. Highest grain yield, biomass, harvest index, accumulated incident PAR, accumulated intercepted PAR, grain filling period and growth duration were obtained in transplanting on 5th may ( 7204 kg. ha-1, 17229 kg. ha-1, 41. 9%, 1050 MJ. m-2, 827 MJ. m-2, 20. 6 and 105 days, respectively) and lowest in transplanting on 10th June. Results of this experiment showed that changing in transplanting date of rice varieties caused changing in mean temperature during growth period, accumulated incident PAR and accumulated intercepted PAR as fallow, but had non significant effect on radiation use efficiency.

To investigate the relationships among effective traits on grain yield and determination of and the relationships among them, 137 rice recombinant lines from F6 population along with four control cultivars (Tarom Deilamani, Hashemi, Saleh and Ali Kazmi) were evaluated for nine important agronomic traits and two crop seasons (2015-2016) in a augment design with four blocks. The results of analysis of variance indicated a significant difference among the lines for all evaluated traits. Also, the differences among control varieties were significant for all traits except for leaf length and width. Simple correlation coefficients were calculated for each year separately and showed that 100 seed weight, number of fertile tillers, number of filled grains, panicle length, leaf length and leaf width had a positive correlation with grain yield. Multiple regression analysis by stepwise method was calculated for each year separately and the results showed that for the first year, 100-grain weight and number of filled grain per panicle traits were entered into model, respectively, that explained 62 percent of grain yield variations. For the second year, 100-grain weight, number of filled grain per panicle and number of panicles traits were entered into model, respectively, that explained 73 percent of grain yield variations. Also based on path analysis results, after 100-grain weight (0. 926), the number of tiller (0. 739) and number of filled grain per panicle (0. 682) traits have the most and positive direct effect with grain yield and thus, these traits could be considered as selection criteria for grain yield improvement in rice. The lines include 9, 132, 133, 24, 52, 83, 5, 40, 78 and 19 were selected as elite lines based on the above criteria. Due to the fact that these traits had a great effect on yield, the selected genotypes can effectively be used as high yielding lines for future studies based on these indices.

To evaluate rice genotypes to drought stress and determine the effective traits on grain yield, 18 rice genotypes (14 M5 mutant lines and four drought sensitive cultivars) were studied in two separately experiments under normal irrigation and drought stress conditions in reproductive stage based on randomized complete block design with three replications at Rice Research Institute of Iran (RRII), Rasht, Iran, during 2014-2015 growing season. Genotype by trait (GT) biplot analysis indicated positive correlations between grain yield and tiller number, grain productivity and width of grains in normal irrigation condition and width and length of grains, number of tillers, grain productivity and number of filled grains in drought stress condition. Stress tolerance index (STI), mean productivity (MP), geometric mean productivity (GMP) and harmonic mean (HM) indices were as suitable indices to select the high-yielding genotypes under drought stress condition. Based on drought stress tolerance indices and overall performance of traits under drought condition, Khazar, Hashemi, Tarom and Gilaneh were as the most sensitive genotypes and mutant lines G1, G2, G3, G4 (derived from Tarom) and G7 (derived from Hashemi) with 2788. 33, 2163. 00, 2178. 33, 2194. 00 and 2375. 00 kg. ha-1 grain yield in drought stress condition, were the tolerant genotypes. Stress tolerance score (STS) were also introduced the above genotypes as tolerant genotypes. Therefore, it is seems that use of mutations has been able to increase drought tolerance on the progenies. The above mutant lines in addition to use as parents in crosses, could also be used in the introduction of drought tolerant cultivars.

Interference interaction of two rice cultivars (Hashemi and Khazar) with Bolboschoenus planiculmis in planting ratios of 4: 0, 3: 1, 2: 2, 1: 3 and 0: 4, rice seedling: weed tuber were investigated in a replacement series studies. The results showed higher height for Hashemi cultivar than Khazar and B. planiculmis and less tiller number and total dry weight for both rice cultivars comparing to B. planiculmis. Stem multiplication and dry matter production of B. planiculmis decreased more in competition with Hashemi than that with Khazar. Total production of rice tillers and weed stems per pot increased with raising the ratio of weed at the planting proportion. Multiplication of one tuber of weed comparing to three plant of rice was four times more and produced equal dry weight. Relative yield, rice aggressivity index and relative crowding coefficient showed more competitive ability for weed against both rice varieties. As the ratio of rice at the planting proportion raised, biological yield, grain yield, panicle number, and total, filled and unfilled seed number increased. At the competition condition, lower biological yield and panicle length, while higher harvest index, panicle number and 100-seeds weight for Hashemi than khazar. In general, this experiment indicated greater competitiveness for B. planiculmis than the rice cultivars, and Hashemi cultivar showed more interference interactions on the weed than Khazar.

Biplot related to the effects of genotype and genotype × environment is called GGE biplot. This method is used to assess the stability of genotypes. In this methodology, selection of sustainable varieties is based on genotype and genotype by environment interaction effects. In this research, the stability of 18 bread wheat genotypes was investigated in six environments (three years and two environmental conditions, irrigated and rainfed). The experiment was carried out in randomized complete block design with three replications under both conditions in experimental field of Faculty of Agriculture, Razi University, Kermanshah, Iran, during three years (2010-2012 and 2014-2015). The results of combined analysis of variance showed that the environment, genotype and genotype by environment interaction effects were 75%, 5. 9% and 14. 9% of total variance, respectively. Pishtaz and WC-4530 genotypes were the nearest genotypes to ideal genotype. Due to the high correlation between E1 (rainfed condition, 2010-2011) and E2 (irrigated condition, 2010-2011) and among E5 (rainfed condition, 2014-2015), E3 (rainfed condition, 2011-2012) and E4 (irrigated condition, 2011-2012), these environments were identified as similar environments. Simultaneous evalution of stability and yield of the studied genotypes showed that WC-4530 is stable and high yielding genotype. View of polygon graph revealed five superior genotypes and three mega-environments, and the compatible genotypes were determined for each mega-environment. All experimental environments had good differentiation ability.

To determine drought tolerance of bread wheat genotypes, nineteen commercial varieties along with nine promising lines were studied in research field of Darab Agricultural and Natural Resources Research Center, Fars province, Iran, for two cropping seasons (2015 – 2017). The experiments were conducted in a randomized complete block design (RCBD) with two replications under water stress at flowering stage and non-stress (normal irrigation) conditions. Thirteen selection indices including stress susceptibility index (SSI), stress tolerance index (STI), tolerance index (TOL), yield index (YI), yield stability index (YSI), mean productivity (MP), geometric mean productivity (GMP), abiotic-stress tolerance index (ATI), stress susceptibility percentage index (SSPI), stress non-stress production index (SNPI), relative drought index (RDI), harmonic mean (HM) and percentage of yield decrease (R%) were evaluated based on grain yield under drought-stressed and irrigated conditions. Also, selection index of ideal genotype (SIIG) based on all tolerance indices was defined and calculated. The results of grouping these indices based on the principal component analysis (PCA) classified them into three groups and the second group indices (HM, GMP and STI) showed the highest positive correlation with grain yield in both non-stress and drought stress conditions. Based on the results of SIIG index, the S-92-13 and Baharan genotypes with the highest SIIG (0. 709 and 0. 701, respectively) were the most ideal genotypes and Narin with the lowest SIIG (0. 324) was the most susceptible genotype to drought stress. Three dimensional diagram of principal component analysis showed that the genotypes G5 (Sirvan), G22 (S-91-15) and G27 (M-92-20) with the higher grain yield than total average and high SIIG were most tolerant genotypes to drought stress. The results of this research showed that SIIG index could be used as a suitable method for identifying drought tolerant genotypes with the help of other drought tolerance indices.

Wheat take-all disease caused by Gaeumannomyces graminis var. tritici is one of the serious wheat diseases in our country, Iran. The Pseudomonas fluorescens bacteria by root colonization and antibiotic production ability are an important biologic control agent of soil born disease. In this study, presence of the phenazine 1-carboxylic acid synthase gene was tracked in 21 Pseudomonas fluorescens isolates via PCR using specific primers of PCA2a and PCA3b. Also, the ability of antimicrobial metabolites production by all of these bacterial isolates such as siderophore and hydrogen cyanide and influences on the growth of pathogenic fungi was investigated via in vitro culture. Ability of the selected bacterial isolates for controlling wheat take-all disease were tested in a greenhouse experiment using a completely randomized design with three replications. The results showed that bacterial isolates were able to produce siderophore and hydrogen cyanide under in vitro conditions. The results of the greenhouse experiment showed that wt_20، eq1_3، wt1_65، eq1_4، 2_79، whm_ و 3 wbo2_7 isolates had positive effects on a number of wheat growth factors such as root/shoot length, root and shoot dry/fresh weight and also reduce in the pathogenicity index was effective in controlling take-all disease in effected plant. In total, the results of this research showed that P. fluorescens bacteria can be used to biologic control of the take-all disease.

A successful hybrid maize (Zea mays L. ) seed production program depends on conformity and synchrony of growth and developmental stages of the parental inbred lines with environmental conditions. Crop simulation models plays a key role in managing such synchrony by providing the simulation of the growth stages occurrence time. To evaluate the power of the DSSAT-CSM-CERESMaize model to simulate the growth and developmental stages of B73 maize inbred line, an experiment was performed as split plot in randomized complete block design with four replications in Karaj, Iran, in 2013. The experimental factors were including planting date and plant densities in five and four levels, respectively. Time to reach any of the developmental stages of B73 maize inbred line including emergence (VE), tassel initiation (TI), silk appearance as the crop flowering (R1), completion of fertilization or beginning of the seed filling (R2) and physiological maturity (R6) were recorded. Then, the genetic coefficients used in the model including P1, P2, P5 and PHINT were determined based on generalized likelihood uncertainty estimation using GLUE software. These genetic coefficients were 307, 0. 33, 970 and 70, respectively. The normalized root of error mean square (nRMSE) values for the recorded five growth stages were calculated as 7. 857, 14. 0, 7. 141, 3, 607 2. 687, respectively, which show the model can simulate the growth stages of B73 maize inbred line using the new specific genetic coefficients. Overall, the results of current research showed that the CERES-Maize model which already developed to simulate the growth and development of maize hybrid cultivars can be efficient and accurate to simulate the production of maize hybrid seed only if the specific genetic coefficient of each parental inbred line is used.

To evaluate the general and specific combining ability of maize lines, five S7 maize lines and their offsprings were evaluated in randomized complete block design with two replications under normal and water deficit conditions at the research field of Graduate University of Advanced Technology, Kerman, Iran, in 2017 and grain yield and its components were measured. The results of analysis of variance indicated that there was a significant difference between lines as well as general and specific combining ability of parents and hybrids. Based on the results of the diallel analysis by second Griffing’ s method, number of grain per row, number of grain rows, number of grain per ear, ear length and 100 grain weight were more influenced by the additive effects than the non-additive gene effects, while the number of ear was more controlled by the non-additive gene effects and grain yield per plant was approximately controlled by equal portion of the additive and non-additive gene effects. The line KSC704-S7-1 showed significant and positive general combining ability for grain yield and more related traits under both water deficit stress and non-stress conditions, so this line can be used to improve grain yield in breeding programs. In addition, P1×P3 and P2×P5 hybrids showed significant and positive specific combining ability for grain yield and most related traits under water deficit stress and normal conditions, respectively, which are introduced as the best hybrids for improving maize grain yield under water deficit stress and normal conditions, respectively.

To investigate the effect of Piriformospora indica fungus on absorption and radiation use efficiency of millet under water stress, an experiment was carried out as a split plot in randomized complete block design with three replications in research field of Faculty of Agriculture, University of Bu-Ali Sina, Hamedan, Iran, during 2014 and 2015. The main factor was irrigation in three levels (irrigation after 60, 90 and 120 mm evaporation from pan class A) and sub factor was in two levels of fungus P. indica (inoculated and non-inoculated). In the both years, water stress decreased leaf area and dry matter accumulation of millet. Inoculation with fungus, increased leaf area and dry matter of millet plants in different irrigation levels. The highest radiation use efficiency (2. 31 and 2. 53 g. MJ-1 in 1st and 2nd years, respectively) was obtained in inoculated millet plants under well-watered, and the lowest (1. 96 and 2. 08 g. MJ-1 in 1st and 2nd years, respectively) was observed in non-inoculated plants under severe water stress. Severe water stress significantly decreased grain yield of millet in both 1st and 2nd years about 57. 53 and 46. 91 percent, respectively. Under severe water stress, inoculating increased grain yield by 35. 34 and 32. 50 percent in 1st and 2nd years, respectively, compared to control (non-inoculated). The results showed P. indica fungus, had a positive effect on absorption and radiation use efficiency of millet in different irrigation levels, so that the application of fungus mitigated the effects of water stress and improved the yield of millet under water stress.