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Articles by H. Pakniyat
Total Records ( 8 ) for H. Pakniyat
  L. Nazari and H. Pakniyat
  The genetic diversity among cultivated barley with different responses to drought stress was investigated. Initial screens involved growing 16 cultivars under drought conditions in greenhouse. These tests involved 5 tolerant and 5 sensitive types. The results of RAPD analysis indicated its suitability for determination of polymorphism among the samples. Among 30 primers used with RAPD-PCR technique, primers No. 3, 26 and 28 did not assist amplification of any definite bands and primers No. 24, 25 did not produce any scoreable polymorphic bands. In all the 25 selected primers amplified a total of 275 amplicons from 16 barley genotypes were detected, among them, 65 fragments (23.6%) were monomorphic and the rest (76.4%) were polymorphic between one or more genotypes. The cultivar genotypes were clustered according to their simple matching coefficient and complete-link methods. The least similarity was observed between wild genotype (Plot 21) and Valfajr. In general, Rihane with the average of 50.6% and Kavir with the mean of 60.8% had the least and the most similarity with other genotypes, respectively. Primer No. 27 amplified a 600 base pair fragment characteristic of tolerant cultivar lines and absent in susceptible genotypes. Therefore, it is likely that this DNA band be associated with drought tolerance. Clustering on the basis of 51% similarity ranked genotypes into 5 groups. The resulting dendrogram indicated that the cross of tolerant wild genotype (Plot 21) and susceptible Sina genotype which have low genetic similarity, also grouped in distinct cluster. This may be suggested as the most suitable cross to analyze QTLs (Quantitative Trait Loci) involved in drought tolerance.
  M. Goudarzi and H. Pakniyat
  The effects of salt stress (NaCl and Na2SO4 in 1:1 ratio) on the activity of peroxidase (POD), proline accumulation, protein, Na + and K + contents and K + /Na + ratio were studied on leaves of two maize and wheat genotypes. Wheat cvs., [Kavir (tolerant) and Ghods (sensitive)] and maize cvs. [704 (tolerant) and 666 (semi-tolerant)] were grown under control (ECe = 1.26 dS m 1) and two levels of salinity (ECe = 6.8 and 13.8 dS m 1, respectively) in a greenhouse. A Completely Randomized Design (CRD) with factorial treatments with three replications was used. Salinity stress decreased K + and K + /Na + ratio and increased Na + , proline, protein and POD activity in both genotypes of wheat and maize under both salinity levels. Furthermore the results showed a lower amount of proline, protein and POD activity in wheat than maize cvs. On the other hand, the higher amounts of K + and K + /Na + ratios which were found in wheat than maize resulted in better ion homeostasis in wheat that caused this species to have a higher tolerance than maize. In wheat cvs.; salinity stress resulted in an increase in proline and protein contents, POD activity, K + and K + /Na + ratio in Kavir cultivar than Ghods. However, Ghods cultivar showed a higher Na + content than Kavir. In maize, cultivar 704 showed a higher increase in proline and protein contents, POD activity, K + and K + /Na + ratio and a lower increase in Na + than 666 cultivar. Maize cvs. showed a higher level of proline, protein and POD activity than wheat cvs., but these components may have been a reaction to salt stress in maize and not a plant response associated with tolerance. The results of this study suggest that Na + and K + contents and K + /Na + ratio in maize as a C4 plant and in wheat as a C3 plant may be considered for selecting the tolerant cultivars.
  R. Naderikharaji , H. Pakniyat and A.R. Biabani
  The aim of this research was to investigate SPAD meter readings variations of rapeseed leaves under different treatments. A pot experiment was conducted at a controlled glasshouse in College of Agriculture, Shiraz University, Shiraz, Iran in 2006. Treatments were various rapeseed cultivars (Hayola 401, Hayola 308, Option and RGS) and irrigation regimes (FC (non-stress), 75 FC, 50 FC and 25% FC). The factorial set of treatments was arranged within a randomized complete block design with three replications. The results showed that with increase in drought stress, SPAD meter readings (the relative chlorophyll concentration of leaves) were decreased. Results showed that, drought stress had a significant effect on net photosynthesis (A), stomatal conductance (gs) intercellular CO2 concentration (Ci) and leaf area (LA) of rapeseed at both vegetative and flowering stages. In general, Hayola 401, had the highest yield in both control and drought treatments, followed by Hayola 308, whereas RGS had the lowest yield among the cultivars. Hayola 401 and Hayola 308, had the highest gs in control and the lowest gs in drought treatments. Cultivars tolerance rankings in this study, was Hayola 401, Hayola 308, Option and RGS. Information obtained in this study may be useful for breeders to introduce suitable drought resistant rapeseed cultivars under arid regions.
  M. Goudarzi and H. Pakniyat
  In a pot experiment, 15 cultivars of Iranian wheat (Triticum aestivum L.) were evaluated at glasshouse for proline and protein concentrations, peroxidase (POD) activity, SSI and STI in response to salinity (NaCl and Na2SO4 in 1:1 ratio). A Completely Randomized Design (CRD) with factorial treatments in three replications was used. Using three salt treatments: 1.26 (control), 6.8 and 13.8 dS m-1. Salinity caused increase in proline and protein and POD activity in wheat genotypes in two salinity treatments. Kavir, Niknejad and Marvdasht showed high increase in some of studied traits compared with Ghods, Zarin and Cross Adl (sensitive cultivars). Based on studied traits other genotypes may be considered as semi-tolerant cultivars. Furthermore, tolerant cultivars showed higher STI and lower SSI compared with non-tolerant cultivars. Result showed that salinity tolerances are associated with higher accumulation of proline and protein concentration and higher POD activity in wheat.
  L. Nazari and H. Pakniyat
  In order to evaluate quantitative drought resistance criteria in some wild and cultivated barley, sixteen genotypes were tested under two different irrigation regimes (non-stressed and stressed). Plants were subjected to moisture stress at flowering period till maturity. Six drought tolerance indices, Stress Tolerance Index (STI), stress tolerance (TOL), Stress Susceptibility Index (SSI), Yield reduction ratio (Yr), Mean Productivity (MP) and Geometric Mean Productivity (GMP) were used. The indices were adjusted based on grain yield under stress (Ys) and non-stress (Yp) conditions. There were significant differences for all criteria among the genotypes. The significant and positive correlations of Yp with (MP, GMP and STI) and Ys with (MP, GMP and STI), as well as, significant negative correlation of SSI and TOL under stress environment, revealed that selection could be conducted for high values of MP, GMP and STI under both conditions and low values of SSI and TOL under stress condition. The correlation coefficients indicated that STI, MP and GMP are the best criteria for selection of high yielding genotypes both under stress and non-stress conditions. Results of calculated gain from indirect selection indicated that selection under moisture stress would be efficient in yield improvement compared to non-stress condition. Genotypes were significantly different for their yield under stress and non-stress conditions. Arivat (kavir), Aras, Goharjo and Afzal were the most desirable genotypes for both stress and non-stress environments.
  A.R. Biabani and H. Pakniyat
  Fifteen sesame genotypes were grown in a randomized complete block design with 3 replications during 2004, in experimental station of Agricultural College, Shiraz University in Badjgah, Iran. Many plant traits were scored in the field. Path coefficient analysis and factor analysis divided the 15 measured variables into 5 factors. The 5 factors explained 81% of the total genetic variation in the dependence structure. Factor 1 was strongly associated with number of capsules in the main stem, length of floral axis, number of capsules per plant and plant height. Other factors (2, 3, 4 and 5) explained the rest of genetic variations and may not be important in sesame breeding programs.
  H. Pakniyat and A. Namayandeh
  Randomly Amplified Polymorphic DNAs (RAPDs) were used to search for markers associated with salt tolerance in barley. Initial screens involved growing 63 cultivated and wild barley genotypes in saline conditions and testing for shoot sodium content along with other physiological traits. From these tests 5 tolerant and 5 non-tolerant genotypes were selected. DNA from the tolerant and non-tolerant genotypes were formed into two contrasting bulks and interrogated using 30 different 10-mer RAPD primers. One primer (P15) produced a 5100 bp band found only in non-tolerant genotypes and additionally produced a 1300 bp product found only in the tolerant group. Primer P10 produced a band specific to tolerant bulk and P22 produced a band specific to the non-tolerant group.
  H. Pakniyat and M. Armion
  Twenty eight sugar beet genotypes were analysed for their tolerance at 3 NaCl levels (0, 3000 and 6000 mg NaCl kg‾ 1 soil) and Na+, K+, Na+/K+ and free proline were measured from the leaf samples. Results showed that increasing salinity level caused an increase in Na+, Na+/K+ and proline, but a decrease in K+ content of leaf samples (p ≤0.01). As compared to non-tolerant genotypes, tolerant ones accumulated more Na+ and Na+/K+ and proline and less K+. It seems that Na+ and proline accumulation in shoots are effective mechanisms for osmotic pressure adjustment and plant tolerance to salinity, a mechanism commonly seen in sugar beet ancestors.
 
 
 
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