Crop breeding

339 5. Perspectives and Challenges 395 Acknowledgements 398 Appendix A. Evolution of the investment into nutrient uptake, effects on emergent functioning 398 Appendix B. Mixing group selection and individual selection in co-evolutionary models 401 Appendix C. Effects of enrichment on the control of biomass within a tri-trophic food chain when the herbivore evolves 402 Appendix D. Eco-evolutionary dynamics in a plant-herbivore-predator confronted to insecticides 407 Appendix E. Evolution of specialization rate of the pest and its ecological consequences 413 Glossary 416 References 417

The use of high yielding and resistant to drought stress cultivars in crops is one of the proper way to incorporation other water deficit management methods. This study in order to evaluate grain yield and morphological traits, an experiment was conducted with 100 genotypes of durum wheat which were planted based on lattice design with three replications under normal and drought stress conditions at the Agricultural Research Station in Varamin. The results showed that total dry matter have a highest positive direct effect on grain yield, whereas, grain yield filling period had the lowest effect and grain yield filling period via harvest index had the positive indirect effect on yield. Under stress condition, peduncle length had the highest positive direct effect on grain yield whereas, spike number, plant length, total dry matter, and date from germination to maturity had negative and direct effect. Factor analysis explained 80.5 and 83.3 of the total variation under normal and drought conditions, respectively. To estimate better grain yield, drought tolerance indices were determined and genotypes 3, 45 and 21 were identified with the lowest value of the indices MP, GMP and STI that were for drought condition while genotypes 45, 21, 71, 34, 78 had the highest value of the mentioned indices and were suitable for both conditions. Cluster analysis grouped genotypes into four clusters in both conditions which confirmed the results of stepwise regression as well as path analysis that could separate genotypes with high grain yield from others as well as traits affecting yield compared to other traits.

The nutrient components and functional properties of Discorea alata were determined. The average crude protein of D. alata was 6.7%. Carbohydrate (81.6-87.6%) was the predominant fraction of the tuber dry mater. The mineral contents of the yam tuber varieties were also evaluated with values ranging from 240-400mg/100g, k; 190-380mg/100g, Na; 180-340mg/100, P; 20.2-80.2mg/100g, C and 24.3-97.2mg/100g, Mg. Vitamin C content of the yam tubers ranged from 16.7-28.4mg/100g, fresh weight. Significant differences in the crude protein and mineral contents were observed among the varieties. Functional property levels in the yam tubers were found to be in the range of 0.64-0.76g/cm (BD); 2.90-3.65g/g (WAC); 27.0-3.5 sec 3 (wettability) and 30-50% w/v (gelation). Significant differences in the functional properties of the yam tuber varieties were also observed. The overall results are indication of good nutritional quality and functional properties of D. alata.

Black cumin (Nigella sativa L.) is one of the medicinal plants of Ranunculaceae family. Its seeds are containing oils, proteins, alkaloids (such as nigellicine and nigellidine), quinines (such as thymoquinone), sapiens and essential oil. Genetic diversity is important in breeding programs, so that selection depends on the existence of genetic diversity in traits. Therefore, an investigation was carried out to select the most successful Black cumin ecotype (s) and to assess the genetic diversity according to the morphological and agronomical traits in some of black cumin ecotypes at two locations based on randomized complete block design with 4 replications (in the research filed of Mohaghegh Ardabili University and Khalkhal city). The results of analysis of variance showed significant differences among studied traits in both locations, wich indicates the existance of genetic variation between ecotypes and the difference in location effect on yield and morphological traits of black cumin ecotypes. According to the results of correlation analysis, it can be concluded that the biological yield, leaf number, number of stem branches and number of flowers and follicle were the most important and effective traits affecting yield and considering that among genotypes, the biggest diversity were observed for these traits, therefore, selecting and breeding for these traits can ideally improve the grain yield. Comparison of means of grain yield showed that Karaj, Ardabil 1, Takestan, Hamadan, Lordegan ecotypes were superior to other ecotypes in both locations.

Drought is one of the major environmental limiting factors in the global agriculture. Exploiting of crop yield potential and increasing yield stability of them in drought and droughtprone regions can be guaranteed to feed the world's growing population. For this purpose, in order to assess the late season drought tolerance genotypes and determining of tolerant them using stress tolerance indices, 21 genotypes of barley in a Randomized Complete Block Design with three replications in two environments (stress and non-stress) in crop year 2014-2015 at the Agricultural Faculty of Tehran University in Karaj were tested. For stress creation, irrigation at first spikelet of inflorescence visible (Zadoks scale, code 50) was stopped. Genotypes yields in non-stress (Yp) and stress (Ys) measured and analysis of variance was performed on them. MP, GMP, STI and HARM indices which showed the highest correlation with yield in stress and non-stress conditions were introduced as superior indices for screening genotypes. The results of principle components analysis and biplot diagram showed that Rihan03, Yousef and Fajre30 had the highest, Rihan, Morocco-9-75 (susceptible control) and Sahra had the lowest drought tolerance genotypes respectively and D10 line had the highest yield in non-stress and was relatively tolerant. Cluster analysis based on MP, GMP, HARM, STI, TOL and SSI indices and yield under stress and non-stress conditions classified genotypes in six clusters. Most drought tolerant genotypes with high yield that their yield difference between stress and non-stress conditions was lower than the other genotypes, were located in sixth, fifth and fourth clusters and sensitive genotypes were located in first and third clusters. Based on the obtained results, Rihan03, Yousef and Fajre30 genotypes were late season drought tolerant, Nik, Kavir, Inc73 and Inc79 genotypes were relatively drought tolerant and Rihan, Morocco-9-75 (susceptible control), Sahra and Inc82 genotypes were identified as sensitive. Probably, D10 Line is also due to a very good yield in non-stress and medium in stress conditions has the potential to become a good commercial variety.

Drought and changes in weather conditions, cause damage and reduce their agricultural products. The fact that durum wheat, after common wheat or Simultaneous with that, is one of the major sources of food supplies, makes it a necessity to identify its drought tolerant species.This article reports an experiment on the impact of different levels of drought (5,10,20, 25 percent of field capacity) on activity of antioxidant enzymes, including Catalase (CAT), Poly phenol oxidase (PPO), Ascorbate peroxidase (APX), Guaiacol peroxidase (GPX), and also some photosynthetic pigments (Chlorophylls a, b, total Chlorophyll and Carotenoid), as well as some osmosic regulators include Carbohydrates and Proline in durum wheat genotypes (Shabrang, Behrang, Karkhe, Aria, Dena). This experiment was designed as a factorial randomized blocks with three repeats, conducted at the Institute for Biotechnological Research in the University of Zabol. Following planting the seeds in pots, the drought stress was introduced at the tillering stage, after which the attributes of the plants were measured. The results of analysis of variance demonstrated that the impact of genotype, drought stress, and the interaction of stress and drought were statistically significant at 1 percent and 5 percent in all the attributes under investigation. The impact of genotype and drought stress on polyphenol oxidase trait was not significant. The most significant effects observed were those of 5 percent watering level of the capacity on antioxidant activity and osmos regulator. The results of this study indicated that in the conditions of this experiment, Behrang and Karkheh genotypes determined the highest level of photosentises pigments and Shabrang genotype have most level of antioxidant activity and Karkheh genotype have highest level of proline and carbohydrate contain, identifying it as a drought tolerant species.

Ultrasound has multiple industrial, medical and biotechnological applications. Ultrasound increases membrane permeability and causes several biological effects in plant cells. In this research, the effects of ultrasound on survival and growth of the sainfoin shoot apex explants were investigated. For this, shoot apex explants were exposed to ultrasonic waves (Frequency 37 kHz) for 0, 20, 30, 40, 50, 60, 90, 120, 180, 240 and 300 seconds in a ultrasonic bath and then cultured on MS medium supplemented with 0.1 mg/l IBA and 3 mg/l BAP. Results showed that the percentage of shooting (explants with shoot growth) significantly reduced by ultrasound treatment, but percentage of multiple shoots, number of shoots per explants and percentage of callusing significantly increased. Control treatment (without ultrasound) showed the highest percentage of shooting with the lowest callus induction and percentage of explants vitrification. The highest percentage of callus induction (60.98% and 61.11%) was observed in higher sonication dosages (180 and 240 seconds). While, the highest percentage of multiple shoots, number of shoots per explants and percentage of explants vitrification were obtained in 30 seconds ultrasound treatment. Increasing ultrasound treatment duration decreased viability of plant cells and tissues, and as a result reduced shooting of explants.

Salinity is one of a major abiotic stress, specifically on arid and semi-arid areas that has influenced on crop growth and reduced grain yield. The purpose of present study was identification of agronomic traits related to wheat grain yield variation under control and salinity conditions. In order to produce a population of 272 recombinant inbred lines (RILs), a cross between two bread wheat cultivars, namely Roshan and Sabalan, was made and the resulted seeds were cultivated under control and saline conditions at a research field of Yazd during 2011-2012 cropping season. The trial was arranged in an alpha-lattice design with two replications. Grain yield, harvest index, biological yield, 1000-kernel weight, grain weight per spike, number of grain per spike, height plant was evaluated on harvest time. In order to study relationship between wheat grain yield and some agronomic traits in both control and stress conditions was used five statistical methods including simple correlation, multiple linear regression, stepwise regression, principle component analysis and factor analysis. The results were indicated that biological yield and harvest index were the most important variable explained grain yield under both sets of conditions. Therefore, grain yield can be increased with biological yield and harvest index enhancement under control and stress conditions.

Abiotic stresses are the most important factors that reduce the yield of crops. In this case, Bioinformatics analysis plays an important role to study genes, and their relatedness as well as prediction their function in response to abiotic stresses. Among all domains, ARID-PHD domain has been identified in plants and animals and has a very significant role in growth regulation, cell cycle, and expression of specific genes in each tissue. In this study, we looked for the conserved sequences of the ARID family in various plant species from the NCBI database to evaluate its expression in Aeluropus littoralis. Based on the result, 10 plants that had protein containing the ARID-PHD domain were identified. Then, sequences alignment, designing phylogenetic tree, protein characterization and relative expression assessment of ARID gene in Aeluropus littoralis were done. The results showed that in addition to the similarity of amino acid sequences, proteins were divided into two groups of monocotyledons and di-cotyledons plants. Protein characteristics and structure investigation indicated a high degree of conserved sequences in proteins from different plant species. Regarding gene expression analysis, the maximum level of transcripts belongs to this gene expressed in plant aerial tissue after 6 hours of salinity stress and did not show a significant decrease until 24 hours, which probably suggested the probable role of this protein in plant tolerance to various stresses. Also, in the root, the gene expression was not significantly different from control treatment. This study was the first report to investigate protein characteristics and changing in ARID gene expression in halophyte plant (Aeluropus littoralis) under salt stress conditions and could be used as a useful reference to make plants tolerable specifically to salinity in using this gene family to modify plants to tolerate abiotic stresses especially salinity.

To investigate some quantitative and qualitative traits of genotypes a field study was performed as augmented experiment consisting four checks (Sadri, Koosha, KS21676 and KS21682) and138 genotypes. Vegetative, morphological and agronomical characteristics as well as traits related to pod and seed were studied. Statistical analysis showed that number of seeds per plant and plant height had the greatest variations. Genotypes had significant differences in all growth stages, yield and yield components. Correlation analysis revealed that five traits including days to emergence of the first trifoliate leaf (V 3), plant height, plant type, seeds per pod and grain marketing were significantly correlated with grain yield. Five traits entered into the model based on stepwise regression analysis that were plant type, seeds per pod, grain filling duration (GFD), V 3 and grain marketing. Path analysis results indicated a high direct effect of plant type on grain yield. Due to available direct effects, it was recommended seeds per pod, GFD, V 3 and grain marketing for breeding programs. Overall, due to path analysis results, can be said that the characteristics plant type, seeds per pod and GFD were the most effective direct factors in grain yield variations. Factor analysis using principal component method showed that seven main factors explained more than 76% of the total variation.

Water stress tolerance was assessed in three cultivars and seven lines of cammon bean (Phaseolus vulgaris L.) belonging to the commercial black and carioca groups. Two independent experiments, one for each group, were set up in Londrina in the year 2000 wet season. A randomized complete block design was used with splitplots and three replications. The plots consisted of treatments with and without water stress and the splitplots of cultivars and lines. Grain yield and grain yield components were assessed. There was genetic variability among the cultivars and lines, as detected by the estimates of the genetic, environmental variation coefficients and B index. Water stress reduced grain yield by, approximately, 50%, but the IPR88 Uirapuru cultivar, from the black commercial group, and the LP 97-13 and LP 97-4 lines from the carioca commercial group stood out as drought tolerant and showed with high yield potential.

Genotype-environment interaction for plant breeders has been important as it is a complex issue in breeding for high yield varieties and releasing new genotypes. In order to assess adaptability and stability of sunflower varieties in different climate conditions, twelve cultivars were investigated in Karaj, Shiraz, Birjand, Kashmar and Arak in randomized complete block designs with three replications. To study genotype by environment interaction, additive main effects and multiplicative interaction (AMMI) model was used. Analysis of additive main effects (analysis of variance) and multiplicative interaction effects (principal components analysis) revealed that the effect of environment at 1% probability level and effect of genotypeenvironment interaction at 5% probability level were significant and tow first interaction principal components explained 84% of the interaction sum squares. Biplot of first interaction principle and mean yield revealed that Progress genotype had adequate yield and lowest value for first principle component. Therefore this genotype selected as a high yield and stable genotype; Record and Gabur genotypes were stable and high yield following Progress genotype. AMMI2 graph indicated that Progress, Master and Zargol in Arak and Karaj, Favorit, Record and Azargol in Shiraz, Gabur and SHF81-90 in Kashmar and Armaverski, Lakomka, Zaria and Sor in Birjand had specific adaptability. Among all genotypes, Zaria, Lakomka, SHF81-90, Gabur and Zargol had the highest general adaptability.

In order to estimate the effects of general (GCA) and specific (SCA) combining ability, heterosis and genetic control of different traits in rapeseed including yield and seed oil content, six lines of spring type and three testers Opera, Parade and Licord of winter type were crossed in 2014-2015. The 18 progenies and their parents were evaluated in a randomized complete block design at the Dryland Agricultural Research Institute (Sararood) under water-stressed (WS) and well-watered (WW) conditions in 2015-2016 cropping season.The results of line × tester analysis revealed that the GCA due to lines in all traits except for pod length in WW and the SCA due to line × tester in all of the traits except for seeds per pod and oil content in WS, and pod length in WW were significant for both environments.The genetic control of the traits was different in both conditions indicating that the gene effects were influenced by the environment for most studied traits. For seed yield, additive and non-additive effects were more important in WS and WW environments, respectively. Seed oil content had relatively low narrow sence heritability in both conditions. The most heterosis for seed yield was belonged to Comet × Opera (168%, WS) and Amica × Licord (171%, WW) hybrids The highest heterosis for seed oil content was observed in Shiralee × Opera hybrid in both environments (12.6% in WS and 6.4% in WW). The testers Opera and Licord were suitable to improve yield in WS and WW environments, respectively. The lines Comet and Dalgan had the highest GCA and the Dalgan × Licord hybrid had the highest SCA (Top cross) for seed yield in both conditions.

Licorice is a medicinal and aromatic plant that is taken into consideration for its valuable compounds such as glycyrrhizin. Salinity is a major environmental stress that affects the crops productivity. In the present study, the effect of salinity stress (using irrigation treatment with different salt concentrations; 0, 150 and 300 mM) on fresh weight of root and total plant, concentration of pigments, total antioxidant, phenol content, ascorbate peroxide enzyme activity and glycyrrhizin content was investigated. The experiment was performed as a factorial under complete randomized block design with three replications in field assay in Agricultural Biotechnology Research Institute of Iran-Isfahan. This experiments showed that, the irrigation treatmentswith150 and 300 mM resulted in increased necrotic leaves, phenol and glycyrrhizin in licorice, i.e. the plants increased their phenolics and glycyrrhizin content, as a part of the mechanism to resist under stress. Increasing the activity of ascorbate peroxide enzyme in plants exposed to salinity stress, indicating the activation of antioxidative and protective systems, and reduction of oxidative damage in these plants. In salinity tolerant genotypes such as Ilam growth parameters, photosynthetic pigments and glycyrrhizin content were higher than sensitive genotypes. The present study has shown that introduction of tolerant genotypes in filed condition can reduce successfully the adverse effects of salinity stress. Therefore, the results of this research can be useful for cultivation of licorice in saline fields and breeding the tolerant genotypes.

The purpose of this study was to quantify the genetic diversity among popcorn genotypes on the market and in the final test phase, suitable for three environments in Brazil, based on 11 agronomic traits and ISSR markers. In the environment Campos dos Goytacazes a more reliable group formation was observed than in the other environments. The molecular data indicated the presence of cultivars recommended in the same group, as in the case of UFVM2 Barão de Viçosa, IAC 125, Zélia and Jade. This result is an appeal to the few popcorn breeders in Brazil to pay particular attention to increase the genetic diversity among breeding programs conducted by public and private institutions in the country. There was virtually no correlation between the distance matrix obtained by the ISSR marker and the matrices obtained by the agronomic data.

This experiment was conducted to investigate of drought effect on some physiological parameters and amino acids accumulation in two canola cultivars (SLM046 and Cooper; tolerance and sensitive to water stress, respectively). The experiment was carried out during two growth phase (stem elongation and flowering stage) using irrigation levels consisting of irrigation after 80 mm evaporation from class "A" pan as control, no irrigation from stem elongation stage and flowering stage. The results showed that water stress significantly diminished seed yield, stomata conductance, chlorophyll a and b, carotenoid content and soluble protein content in leaves of both cultivars. Also antioxidant enzyme activity (catalase, peroxidase and ascorbate peroxidase) were enhanced with drought stress at stem elongation stage, but peroxidase and ascorbate peroxidase activity were decreased at flowering stage. The amino acids of Tryptophane, serine, glutamine and α-amino butyric acid showed highest abundance of total amino acids at stem elongation stage, also glutamine, isoleucine, serine and histidine revealed highest amount of total amino acids at flowering stage. An increase in contains most of amino acids in response to drought stress at flowering stage was observed. The significant accumulation of aspartic acid, asparagines, glutamine, lysine, cysteine, tryptophan and phenylalanine under drought at elongation stage, and significant accumulation of glutamine, glycine, thyrosine, methionine, phenylalanine and isoleucine under drought at flowering stage were observed in the drought-tolerant SLM046, whereas no were showed the significant accumulation of amino acids in the drought-sensitive Cooper under drought. Thus it can conclude that tolerance of genotypes to drought stress is closely associated with their accumulation of free amino acids.

Water deficient stress is one of the major limiting factors of wheat production in arid and semiarid areas of the world such as Iran. Under water deficient stress photosynthesis is limited and remobilization of assimilates stored in stems is more important to grain filling. In order to molecular analysis of fructan remobilization in wheat stem (penultimate) under terminal water deficit stress, T-65-7-1 mutant line (M 7 , the results of gamma irradiation) along with its wild type (cv. Tabasi), in terms of relative gene expression involved in biosynthesis and hydrolysis of fructan and transport of sucrose were studied. Water deficit treatment (30-40% field capacity) initiated at full heading stage (Zadoks 60) and sampling was conducted at two stages (7 and 21 days post anthesis). In the T-65-7-1 mutant line, a significant increase was observed in expression levels of genes involved in fructan biosynthesis (1-SST and 6-SFT), fructan biosynthesis (6-FEH) as well as sucrose transport (SUT1 and SUT2) compared to the wild type (cv. Tabasi). This event is due to more remobilization in T-65-7-1 mutant compared to the wild type. In T-65-7-1 mutant, during early grain filling period, 1-SST and 6-SFT produces more storage of fructan in the stem. Also, during rapid grain filling stage, 6-FEH produces more sucrose and finally, SUT1 and SUT2 transports more sucrose from stem to grain. In wheat breeding programs, 1-SST, 6-SFT, 6-FEH, SUT1 and SUT2 can be used as indicators for selecting genotypes with high fructan content and more remobilization.

Cytogenetic and pollen viability (PV) studies were performed in pepper accessions, Capsicum chinense and Capsicum baccatum. Irregularities such as laggard and univalent chromosomes, bridges, problems in the spindle fibers and cytomixis were observed, especially in C. baccatum which was the most unstable genotype. In the post-meiotic products, irregularities were observed, on average, at 20 % of the microspores in C. baccatum and 17 % in C. chinense. PV in C. baccatum was below 70 %, while in C. chinense, it was above 80 %. Meiotic irregularities in Capsicum, mainly in C. baccatum, considering the low PV estimated, were significant but not impeditive for fertilization.

Spot blotch disease of barley caused by Cochliobolus sativus, is an important barley disease which causes extensive grain yield losses. In order to understand the inheritance of resistance to the disease, an experiment was conducted using seven barley genotypes in partial diallel crosses. Parents and F 1 crosses were planted in a randomized complete block design (RCBD) with three replicates. The severity of disease was recorded as the first signs of disease and then AUDPC was calculated. D and H components showed that both additive and dominance effects are effective in controlling the traits. Dominant alleles led to a reduction in the severity of disease and increased resistance to spot blotch disease. 67/110 and sahra genotypes have negative GCA and can take advantage of them as promising parents in breeding programs for resistance to the disease.

Barley (Hordeum vulgare L.) as one of the main crops is important economically for Iran. Genetic diversity and it`s evaluation is foundation of plant breeding projects. Awareness about genetic variation is effective in selection of parental lines for future breeding programs. This study was aimed to evaluate both morphological and physiological characteristics followed by classification of 18 barley inbred lines based on RCBD design with four replications. Results of descriptive statistics revealed vast range of variation for most of studied traits. Among studied traits, seed yield with standard deviation of 614.06 possessed maximum divergent. Also, hectoliter weight and grain yield had the lowest and the highest coefficients of variation values of 0.58 and 8.88, respectively. Univariate and multivariate analysis of variance depicted remarkable genetic variation among studied genotypes based on morphological and physiological traits. Classification of studied barley genotypes using both types of inspected traits could classify them in 3 separate groups. In this research, there was not any coincidence between two types of classifications. This is resulted that line number 3 with high pedanclean length (7.18 cm), 1000 kernel weight (42.2 gr), yield (5172.5 kgh-1), dry matter percentage (31.3 %), fresh weight (0.463 gr), turgusens weight (0.717 gr), relative water content (58.82 %) and also another moderate characteristics could considerable as promising one for arid and semi-arid region after regional field trials.

The objective of this study was to estimate genetic parameters and predict genotypic values in sugarcane clones (series RB96) by the Reml/Blup methodology. The trial was installed in an unbalanced block design to evaluate the yield at three locations in the state of Paraná. The ranking of the clones regarding yield differed from one location to the other, due to the genotypic correlation of intermediate magnitude (0.62) across the locations. The two best clones presented a mean superiority of 28% (RB955466) and 19% (RB965518) over the general mean of the three locations. A comparison of the methods Mhprvg (harmonic mean of the relative performance of genetic values, according to Resende 2004) and showed that both selected practically the same clones but the Mhprvg method presented the advantage of providing results in the measurement scale of the evaluated trait.

The genotype by environment interaction is a major challenge in the study of quantitative characters because it complicates the interpretation of genetic experiments and do predictions difficult, also it reduces grain seed yield stability in different environments. In order to determine the yield stability, adaptability and analysis of the genotype × environment interaction of oily sunflower inbred lines under normal and salt stress conditions, 100 genotypes coming from different geographical regions were evaluated using a randomized complete block design with three replications for two successive years (2006 to 2007). In stability analysis using statistics such as environmental variance and coefficient of variation, lines 71 and 33 showed minimum variations compared to other lines. Based on Eberhart and Russell regression method, lines 71, 45, 40 and 25 was the most stable genotypes. AMMI statistics revealed lines with code numbers of 71, 77, 93 and 51 as the most stable genotypes. Biplot technique was used to identify the appropriate genotypes for special environments. Based on this method, lines 71, 61 and 17 showed the lowest interaction and considered as the most stable genotypes. However, line 71 showed highest seed yield compared two other lines. The line with code number of 50 showed special stability and high yield under normal conditions whereas lines 90, 48 showed special stability and high yield under salt stress conditions. In conclusion, based on different stability analysis statistics and AMMI analysis the line 71 are introduced as most stable line under normal and salt stress conditions.

Nowadays, the root characteristics as one of secondary traits along with grain yield are used to response evaluation of rice genotypes under deficit irrigation. Thus, to evaluate the root traits of 40 irrigated rice genotypes to water limited condition a pot experiment was performed in 2014 at Rice Research Institute (Rasht), Iran. Irrigation treatment was applied in two levels include control (traditional irrigation) and deficit irrigation (withholding irrigation at the booting stage). The results showed that deficit irrigation reduced root length from closely 45 to 28 cm, root area from 190 to 117 cm 2 and root area density from closely 6 to 4 cm 2 cm-3. Under deficit irrigation, average of paddy yield and panicle weight decreased 25% and 18.5%, respectively. In this condition, root dry weight decreased, in other hand the shoot dry weight increased from 42.7 to 49.4 g. Genotypes classification carried out based on studied traits by the Ward's Minimum Variance test in both conditions (control and deficit irrigation) that separated the genotypes into four and three groups, respectively. In both situations, groups with lower amount for root traits had the higher paddy yield. Accordingly in deficit irrigation conditions, group III include 19 genotypes such as Gohar, Shiroudi and Khazar with low amount for root characteristics, had paddy yield higher than other groups. Comparison of groups showed that significant variation of root dry weight, shoot dry weight, panicle weight and paddy yield (about +21, +14,-19 and-14%, respectively) in local genotypes compare with improved genotypes. Therefore, it seems that although priorities of crop improvement in studied genotypes were to allocate more dry matter from the root to the shoot, but considerable diversity existed in terms of dry matter partitioning to different organs under deficit irrigation.

Water deficit is one of the most important abiotic factors limiting growth, which adversely affect growth and crop production. In order to study the relationship between kernel size and phenological characteristics on grain yield, local bread wheat genotypes along with four varieties were evaluated in randomized complete block design with three replications under irrigation and water deficit stress conditions. Phenological characteristics including day to heading, day to flowering, day to maturity and grain filling duration, and kernel size traits including kernel length, kernel width, kernel thickness and kernel length/width ratio were measured. Analysis of variance revealed significant differences among genotypes for the studied traits. Results showed drought led to decreased grain yield (.), thousand grain weight (.), spike weight (.), peduncle weight (.), grain filling duration (.), kernel width (.) and increased kernel length/width ratio as compared with irrigated condition. Stepwise regression analysis revealed that under irrigated condition, spike weight, spike length and plant height justified the majority of grain yield variation, whiles under drought stressed condition grain filling duration and kernel width showed the highest impact on grain yield variation. Factors analysis identified four factors which explained. of the total variation. On the basis of these results, it is concluded that criteria such as grain filling duration, kernel width, peduncle weight and thousand grain weight could be considered as effective criteria for selecting to improve grain yield in water-limited environments.