Journal of Plant Physiology and Breeding
Volume:2 Issue: 1, Winter-Spring 2012

The main reasons for the fixation of some elements and consequently nutrient deficiencies, especially phosphorus, iron and zinc, are high levels of calcium (calcareous soils) and soil pH. Two sulfur fertilizers (sulfur alone and sulfur + organic material + Thiobacillus spp.) with two rates (2 and 4 kg sulfur/tree) were used to decrease soil pH and availability of P, Fe and Zn in apple trees during the growing season. A control treatment with no sulfur was also included in the experiment. The experiment was based on randomized complete blocks design with three replications and was carried out in the apple orchards of the West Azarbaijan province. Results showed that the sulfur treatments had significant effects on soil pH, chlorophyll content of leaves and phosphorus, iron and zinc concentrations of leaves and fruits in apple. On the average, applying sulfur decreased pH of soil and increased the chlorophyll content of leaves, and iron, zinc and phosphorus concentration of fruits in apple by17.09%, 4.8%, 30.24%, 11.61% and 18.76%, respectively, as compared to the control. Regarding the soil pH and other criteria about the nutrients availability and concentration, it seems that the application of 2 kg/tree sulfur fertilizer would be beneficial for apple orchards located in the highly alkaline soils of the area under study.

The effect of salinity was assessed on the activity of some major antioxidant enzymes i.e., superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), in the seedlings’ roots or shoots of three winter canola (Brassica napus L.) cultivars, Colvert (tolerant), Symbol (semi tolerant) and Agat (susceptible). Seedlings were treated with 0 (control), 50, 100 and 150 mM NaCl for 24 h in hydropoic conditions. The data were analyzed, using two-factorial balanced analysis of variance on the basis of completely randomized design with three replications. The results showed significant differences among cultivars and among salt treatments. With increasing level of salt treatment, the fresh and dry weight of roots and shoots were reduced in the cultivars under study; Colvert was influenced less than the other two canola cultivars. Salt stress enhanced the activity of SOD, POD and CAT. Almost, the maximum activity of these enzymes was detected in Colvert, the salt tolerant cultivar, followed by the other two cultivars.

In order to evaluate crop water stress index (CWSI) and canopy temperature of wheat cultivars under terminal drought stress, a field experiment was conducted at the Agricultural Research Station of Shiraz University, Shiraz, during 2009 growing season. Five wheat cultivars including Shiraz, Bahar, Pishtaz, Sistan and Yavaros and four levels of water regime including well watering [Irrigation according to 100% field capacity (FC)], excess watering (125% FC), and mild (75% FC) and severe drought (50% FC) stress were used in a split plot design experiment with three replicates. Results showed that Yavaros and Shiraz cultivars with 7.36 and 6.81°C had the highest canopy-air temperature differences (Tc-Ta), respectively, while in Bahar this difference was 3.9°C. In all cultivars, slope (a) and intercept (b) of lower base line equation between Tc-Ta and vapour pressure deficit (VPD) were increased significantly due to more limitation in water and increasing VPD. Yavaros and Shiraz cultivars with higher a value were found to be more sensitive to increasing VPD. Shiraz and Yavaros cultivars with 0.73 and 0.71 had the highest seasonal mean CWSI, respectively, while CWSI in Bahar, Pishtaz and Sistan ranged from 0.61 to 0.64 under severe drought. A negative relationship was found between CWSI and amount of water supply and net photosynthesis of flag leaf. Maximum grain yield was obtained in Shiraz and Yavaros under well and excess watering and CWSI in these cultivars ranged from 0.31 to 0.36, whereas by decreasing water supply and increasing CWSI, grain yield in these cultivars decreased significantly. Bahar, Pishtaz and Sistan cultivars with lower Tc-Ta, water supply and CWSI had better performance than Shiraz and Yavaros cultivars, especially when exposed to water stress conditions. The role of these traits should be further investigated as potential indirect selection criteria for grain yield of wheat cultivars in semi-arid conditions.

Pistacia atlantica is the most important tree species for the economy of many rural areas in west of Iran, but no effort has been made for the genetic improvement of this species. The aim of this investigation was to study the genetic variation and inheritance of early growth traits in P. atlantica. For this purpose, three wild pistachio populations comprising 60 randomly selected adult trees from northwest of Iran were sampled and half-sib seeds were sown in a forest nursery using randomized complete block design with three replications. During the growing season, plant height, collar diameter, number of leaves and sprout length were measured on the seedlings in 2009 and 2010. Analysis of variance based on split plot in time was carried out for the two-year data and squared phenotypic coefficient of variation (PCV2) were calculated for the above mentioned traits. Furthermore, additive genetic variance, narrow sense heritability and expected genetic gain were estimated among the half-sib families under study. In addition, phenotypic correlation coefficients of the traits from 30 two-year old seedlings with several characters of mother plants were calculated. Analysis of variance showed significant differences among trees for all of the seedling traits indicating the existence of enough genetic diversity within this species that can be utilized in breeding programs. Plant height and number of leaves had the highest PCV2 among the measured traits. Narrow sense heritability estimates were moderate for collar diameter (0.53), number of leaves (0.46) and sprout length (0.43) and high for plant height (0.71). Considerable genetic gain was also expected for plant height. In addition, plant height of half-sib progenies was significantly correlated with tree height, stem diameter and maximum seed diameter of mother plants. Therefore, plant height could be regarded as a reliable early selection index because of its high heritability and genetic gain and also, significant correlation with the characteristics of parental trees.

The AMMI and SREG GGE are among the models that effectively capture the additive and multiplicative components of genotype × environment interaction (GEI) and provide meaningful interpretation of multi-environment trials’ data set in the breeding programs. The objective of this study was to assess the effect of GEI on grain yield of barely advanced lines and exploit the positive GEI effect using AMMI and SREG GGE biplot analysis. Therefore, 18 lines were evaluated at four research stations (Gorgan, Mogan, Lorestan and Gachsaran) of Dryland Agricultural Research Institute (DARI), located in the semi-warm regions in Iran, in 2004, 2005 and 2006 cropping seasons under rain-fed conditions. Analysis of variance showed that grain yield variation due to environments, genotypes and GEI were highly significant (p<0.01), which accounted for 70.4%, 6.8% and 22.8% of treatment combination sum of squares, respectively. To determine the effects of GEI on yields, the data were subjected to AMMI and GGE biplot analysis. The first four AMMI model terms were highly significant (p<0.01) and of which the first two terms explained 48% of the GEI. There were two mega-environments according to the SREG GGE model. The best genotype in one location was not always the best in other test locations. According to AMMI1 biplot, the ideal-genotype biplot and by visualizing the mean yield and stability of the genotypes, lines G2 and G11 were better than all other lines across environments. G11 was the ideal genotype to plant in Gachsaran and Lorestan and G2 was the best for Gorgon and Mogan.

To study the effect of water stress in rapeseed cultivars at the seedling stage, 10 rapeseed cultivars were evaluated at three irrigation levels [normal irrigation (control) and irrigation after depletion of 60 and 85% of available soil water]. Analysis of variance showed considerable variation among cultivars. Water stress reduced all of the studied morphological characteristics, especially shoot and root dry weight, root volume and increased chlorophyll content and chlorophyll fluorescence. Cluster analysis at three levels of irrigation regime, assigned cultivars in different groups. Cultivars Licord, Opera and SLM043 were grouped together and showed higher average for all traits compared with other cultivars at all of the irrigation conditions. ISSR analysis using 11 primers produced 54 polymorphic bands in the studied cultivars. Mean PIC and MI of all primers were 0.21 and 1.03, respectively. Cluster analysis based on molecular data using Nei's genetic distance assigned the cultivars into three clusters. Associations between molecular markers and morpho-physiological traits, were assessed by stepwise multiple regression analysis at different stress levels. The highest amount of variation contributed by ISSR markers belonged to relative leaf water content (78%) at non-stress condition, to root/shoot index (66%) at moderate stress condition and to root length (53%) at severe stress condition.