Evaluation of seed yield-related characters in sesame (Sesamum indicum L.) using factor and path analysis.

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.

Sodium and proline accumulation as osmoregulators in tolerance of sugar beet genotypes to salinity.

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 < or = 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.

Salt tolerance associations with RAPD markers in Hordeum vulgare L. and H. spontaneum C. Koch.

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.

Evaluation of some drought resistance criteria at seedling stage in wheat (Triticum aestivum L.) cultivars.

This research was conducted to evaluate some of the drought resistance criteria at seedling stage in wheat. A factorial experiment in a Completely Randomized Design (CRD) was used with two factors consisted of stress levels (0, -5 and -8 bar) using PEG 6000 and genotypes (10 genotypes of bread wheat; Azar 2, Gahar, Koohdasht, Bow, Zagros, Cham, Niknejad, E1 Neilairi, Bohoih and Giza 164) in three replications in a hydroponic condition. Stress Tolerance Index (STI), Water Use Efficiency (WUE), Biological Yield (BY), Shoot Dry Weight (SDW), Root Dry Weight (RDW), Root/Shoot weight ratio (R/S), Root Length (RL), Relative Water Content (RWC), Wilting Percentage (WP) and first and 2nd Leaves Extention Rate (LER1 and LER2) were measured at seedling stage. Increasing stress levels caused reduction in BY, SDW, RDW, RL, RWC, LER1 and LER2, but an increase in WUE, DWR, R/S and WP. Azar2, Gahar, Koohdasht, Zagros and Bow were in favorite condition in regard to STI, WUE and other criteria. Therefore, they are drought tolerant and might be suitable genotypes at water deficit conditions. Niknejad, E1 Neilairi and Cham were moderate and Giza 164 and Bohoih were sensitive genotypes to drought conditions. This research revealed that at -5 bar, WUE, BY, SDW, R/S and LER2 and at -8 bar, WUE, BY and WP were suitable criteria for selection of drought resistant genotypes at seedling stage.

Genetic evaluation of several physiological traits for screening of suitable spring safflower (Carthamus tinctorius L.) genotypes under stress and non-stress irrigation regimes.

Seven cultivars and one line of spring safflower (Carthamus tinctorius L.) were used to estimate genetic variation, heritability, genetic gain and genetic factor analysis for several physiological traits. Each experiment was conducted in a randomized complete block design with three replications. Factor loadings in first factor were used for determination of important physiological traits for suitable genotype screening under each irrigation regimes. Under non-stress conditions, factor analysis technique extracted six factors which exploited about 93% of the total genetic variation, while 30% of the total genetic variance was associated by the first factor. Under stress conditions factor analysis extracted four factors and they totally explained 100% of the total genetic variation, while, the first factor accounted for 38% of the total genetic variation. Ultimate, leaf area index (at stem-elongation and flowering), leaf osmotic potential (at stem-elongation) and rate of water loss from excised leaves (at flowering) under non-stress conditions and also leaf area index (at flowering and grain filling) and rate of water loss from excised leaves (at grain filling) under stress conditions were the best criteria for screening of suitable genotype under explicated conditions.

RAPD markers associated with drought tolerance in bread wheat (Triticum aestivum L.).

Randomly Amplified Polymorphic DNAs (RAPDs) were used to search genetic diversity and markers associated with drought tolerance in 20 bread wheat cultivars. These cultivars are extensively being used by farmers in Iran, 6 of them are known as drought tolerant. Initial screens involved growing 10 cultivars at seedling stage under drought conditions (-5 and -8 bar) exerted by PEG 6000 in a hydroponic experiment. These tests confirmed the tolerance of the 6 above mentioned cultivars. Thirty 10-mer RAPD primers were used for fingerprinting of the cultivars of which primers P6 (TCGGCGGTTC) and P7 (CTGCATCGTG) produced respectively a 920 and a 750 bp band present in drought tolerant (absent in others) cultivars. These bands may be associated with drought tolerance in bread wheat.

AFLP variation in wild barley (Hordeum spontaneum C. Koch) with reference to salt tolerance and associated ecogeography.

Thirty-nine genotypes of Hordeum spontaneum were selected from three geographically separated areas (southwestern, northern, and southeastern) of the Fertile Crescent. The lines were subject to AFLP (amplified fragment length polymorphism) analysis from which a similarity matrix was produced. A dendrogram of the data showed, with two exceptions, that the genotypes grouped together according to area of origin. This was confirmed by principal coordinate analysis in which the first principal coordinate separated the genotypes of the southwestern area from the other two areas, which in turn could be separated by the second principal coordinate. While genotypes from the same site of origin can exhibit very similar AFLP profiles, sharp genetic differences were detected between genotypes separated by relatively short distances. Thirty of the 39 genotypes were subjected to hydroculture salt tolerance tests. These were analysed for shoot Na+ content and carbon isotope composition (δ13C) after 4 weeks of treatment (100 mol∙m−3 NaCl). Shoot Na+ content and δ13C were highly correlated. Twelve AFLP markers were found to be associated with both shoot Na+ content and shoot δ13C and were also associated with site of origin ecogeographic data, particularly longitude. The most salt tolerant genotype came from Ilam in the southeastern area and the most salt sensitive genotype originated in the southwestern area. The 12 markers were partitioned into groups that showed significant associations within groups but no significant association between groups. In a multiple regression analysis, three AFLP markers, from separate groups, accounted for more than 60% of the variation for shoot Na+ content and δ13C. The results demonstrate the effectiveness of AFLP fingerprinting in genetic studies of complex traits at the wild species and (or) population level.