Mehmet Arslan

Estimates of relative yield potential and genetic improvement of wheat cultivars in the Mediterranean region.

Information about changes associated with advances in crop productivity is essential for under- standing yield-limiting factors and developing new strategies for future breeding programmes. National bread wheat (Triticum aestivum L.) yields in Turkey have risen by an average of 20·8 kg/ha/ year from 1925 to 2006. Annual gain in yield attributable to agronomic and genetic improvement averaged c. 11·6 kg/ha/year prior to 1975, but is now averaging c. 15·1 kg/ha/year. In the Mediterranean region, however, the wheat yield trend line (10·9 kg/ha/year) is c. 0·38 lower than that of Turkey. In order to understand whether such a trend was due to the cultivars released over the years, 16 bread wheat cultivars, commonly grown in the region and representing 23 years of breeding, introduction and selection (from 1976 to 1999), were grown in a randomized complete block design with three replicates across 2 years. Data were collected on maturation time, plant height, spike length, spikelet number/spike, grain number/spike, grain weight/spike, 1000 seed weight, harvest index and grain yield. None of the measured plant traits showed any historical cultivar patterns; therefore, the increase in grain yield could not be attributed to a single yield component. Several physiological traits changed during two decades of cultivar releases in the Mediterranean region that led to a genetic gain in grain yield of about 0·5% per year. Years of data and the present field study in the Mediterranean region suggested that the genetic improvement in wheat seemed inadequate and should be reinforced with modern agricultural management practices as well as technological innovations.

Effects of Genotype and Picloram Concentrations on Callus Induction and Plant Regeneration from Immature Inflorescence of Spring Barley Cultivars (Hordeum Vulgare L.)

ABSTRACT The effects of different picloram (4-amino-3,5,6-trichloropicolinic acid) concentrations (2.5, 5, 7.5 and 10 mg. l−ι) in the LS (Linsmaier and Skoog, 8) medium of immature inflorescences taken from four barley (Hordeum vulgare L.) cultivars were investigated. The result of the study showed that callus induction rate, shoot induction rate, callus weight and plant regeneration from the immature inflorescence were significantly affected by the genotypes. There was a significant interaction between genotype and picloram concentrations. Depending on the genotypes, mean callus induction rate, mean shoot induction, mean callus weight (mg/petri dishes) and number of regenerates (per inflorescence segment) varied from 0.0–39.1%, 12.5–29.7%, 0.0–150.3 mg and 0.2–1.5 respectively. Mean callus and mean shoot induction rates, mean callus weight and mean regeneration rate were also significantly influenced by the picloram concentrations. The segments cultured on the LS medium containing 7.5 mg. l−ι of picloram gave the highest values of callus induction rate (31.3 %), shoot induction rate (40.6%) and plant regeneration (1.2 regenerates per segment). In this study, only albino plantlets were obtained.

Greenways and the Urban form: City of Ankara, Turkey

ABSTRACT Greenways can be roughly considered as linear open spaces with connection functions. They are planned along with either natural corridors or other routes designed for multi-functional uses, and differentiated from the remainder of the landscape with its unusual potential and natural character and can be considered as linked parks or greenways. In this paper, greenway concept and the definitions offered for it were discussed. The characteristics of greenways, the benefits and liabilities, goals, landscape context and its sustainability and planning approaches were given. Then, Ankara city, the metropolitan area, was criticized. The existing potential of the urban environment, the possibilities of forming such a greenway system for Ankara, along with the valley systems of the city and their suitability for ecological and recreational purpose, were evaluated. Besides, the vitality of greenways for metropolitan areas/urban development and its positive effects on human health was emphasized.

Growth and development of Virginia type groundnut cultivars under Mediterranean conditions

Abstract The growth and development of groundnut (Arachis hypogaea L.) are under the influence of complex environmental factors. Understanding of the growth responses of the groundnut to environmental factors may improve the application of better management practices and develop better cultivars to overcome the problems causing reductions in yield. A two-year field experiment was conducted to determine the growth and development response of groundnut genotypes to environmental factors in the eastern Mediterranean region of Turkey in 2001 and 2002. Time from sowing to physiological maturity (R8) ranged from 2513°Cd to 2588°Cd in 2001 and from 2514°Cd to 2573°Cd in 2002 while total calendar days varied between 147 and 153 and between 156 and 161 depending on genotypes in 2001 and 2002, respectively. Dry matter accumulation in each part of the plants continued until maturity although accumulation rate differed depending on plant age. Combination of suitable temperature and photoperiod during the reproductive stages resulted in continuous and abundant reproductive plant parts, which led to delayed harvest and increased unmarketable pods. The slower growth rate due to the cooler conditions during early stages caused slower biomass accumulation in successive stages indicating the importance of initial crop growth for final yield. Therefore, the genotypes having high initial growth rate, less reproductive organs, and shorter growing period should be developed for the Mediterranean conditions by breeders. The management studies should also deal with increased initial growth rate and reduced number of flowers, pegs or pods per plant. Based on our results, groundnut has a great yield potential under the Mediterranean conditions. However, further breeding and management studies are needed to improve the yield and profitability and reduce the complications arisen from the Mediterranean climate.

The Cadmium Phytoextraction Efficiency of ScMTII Gene Bearing Transgenic Tobacco Plant

ABSTRACT Cadmium pollution is a serious world-wide problem affecting the human health and the environmental quality. Phytoremediation, the use of green plants to remove, sequester or detoxify pollutants offers an environmentally-friendly alternative to engineering-based methods for remediation. The T2 generations of the ScMTII gene bearing transgenic and non-transgenic tobacco plants were grown hydroponically in Hoagland nutrition solution containing 0, 5 and 10 mg/L Cd in controlled growth room to determine their ability to uptake and accumulate Cd within the shoots and roots. There were no significant shoot and root dry weight differences between transgenic and non-transgenic tobacco plants. The ScMTII gene bearing transgenic tobacco plant accumulated 19.8% higher Cd than the non-transgenic tobacco plant in the above ground parts of the plant during the two weeks exposure period in hydroponic culture. In non-transgenic plant, however, Cd is accumulated mainly in the roots. The results of current study indicate that the use of the ScMTII gene bearing transgenic tobacco plant for Cd phytoremediation is limited. Further studies are needed to test the effectiveness of the ScMTII gene for phytoextraction of other heavy metal ions.

The critical period of weed control in double-cropped soybean

Double-cropped soybean after winter cereals is the most common soybean production system in the eastern Mediterranean region of Turkey. Weeds are among the main obstacles to double-cropped soybean. A study was conducted in 2002 and 2003 to determine the critical period of weed control (CPWC) for double-cropped soybean. The treatments consisted of either allowing weeds to infest the crop for increasing durations after sowing, or maintaining plots weed-free for increasing durations after sowing. The Gompertz and logistic equations were fitted to relative yields representing the critical weed-free period and the critical time of weed removal, respectively. Johnsongrass (Sorghum halepense), common cocklebur (Xanthium strumarium) and field bindweed (Convolvulus arvensis) were the dominant weeds. For 5% crop loss level, the CPWC was almost all season long, whereas it was from V1 to R6-R7 growth stages for 10% yield loss level. These findings indicate that pre-sowing or pre-emergence control methods should be applied in the region to avoid greater crop losses.

Effects of cultivar maturity on growth and yield of double cropped soybean

Abstract Maintaining yield potential or reducing yield losses is very important for soybean [Glycine max (L.) Merr.] double cropping to be profitable. Our objectives were to study the effects of cultivar maturity on yield, yield components and to determine adaptation and yielding potential of 18 soybean cultivars (six cultivars in each of the maturity groups II, III and IV) in the eastern Mediterranean region of Turkey in 2000 and 2001. The experimental design was randomized complete block with three replications. Effects of maturity group (MG) on seed yield, yield components, and key phenological stages were significant. Cultivars in MG IV had significantly higher seed yield, plant height, lowest pod height and number of nodes/plant than cultivars in MG II and III. Among cultivars, the highest seed yield was obtained from KS4895 (MG IV) with 3.75 t/ha and the lowest was obtained from Dwight (MG II) with 1.18 t/ha. Except for the number of seeds/pod, all of the measured yield components and key phenological stages were significantly and positively correlated with seed yield. Based on the path analysis of the combined data, it was found that the number of seed/m2, the period from VE to R1 and from R1 to R7 had greatest positive direct effect on seed yield. The results of the current study showed that cultivars in MG IV were best adapted and best suited for a wheat-soybean double cropping system in the eastern Mediterrenean region of Turkey.

Analysis of genetic diversity of Sclerotinia sclerotiorum from eggplant by mycelial compatibility, random amplification of polymorphic DNA (RAPD) and simple sequence repeat (SSR) analyses

ABSTRACT The genetic diversity and pathogenicity/virulence among 60 eggplant Sclerotinia sclerotiorum isolates collected from six different geographic regions of Turkey were analysed using mycelial compatibility groupings (MCGs), random amplified polymorphic DNA (RAPD) and simple sequence repeat (SSR) polymorphism. By MCG tests, the isolates were classified into 22 groups. Out of 22 MCGs, 36% were represented each by a single isolate. The isolates showed great variability for virulence regardless of MCG and geographic origin. Based on the results of RAPD and SSR analyses, 60 S. sclerotiorum isolates representing 22 MCGs were grouped in 2 and 3 distinct clusters, respectively. Analyses using RAPD and SSR markers illustrated that cluster groupings or genetic distance of S. sclerotiorum populations from eggplant were not distinctly relative to the MCG, geographical origin and virulence diversity. The patterns obtained revealed a high heterogeneity of genetic composition and suggested the occurrence of clonal and sexual reproduction of S. sclerotiorum on eggplant in the areas surveyed.

EVALUATION OF GENETIC SIMILARITY AND AGRONOMIC TRAITS OF CASTOR BEAN POPULATIONS NATURALLY GROWN IN THE EASTERN MEDITERRANEAN REGION OF TURKEY

ABSTRACT Genetic characterization of wild castor bean genotypes collected from the eastern Mediterranean region of Turkey was evaluated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of seed storage proteins. Five distinct groups were identified from the cluster analysis of the castor bean genotypes studied at 0.80 coefficient level. Cluster analysis showed that some of the genotypes from the same location were grouped separately. Genetic similarity coefficients ranged from 0.36 to 0.95 among genotypes. The highest similarity (95%) was obtained between Iskenderun-1 and Iskenderun-2; Adana-4 and Iskenderun-2; Iskenderun-4 and Mersin-1. In addition to genetic diversity, plant characteristics such as stem color, seed color, days to maturity, plant height, main spike length, 100-seed weight and seed yield per plant were recorded. The results of both genetic similarity and agronomic analysis of castor bean genotypes would help in planning breeding programs for improving high yielding cultivars.

Fatty acid characteristics of grass pea (Lathyrus sativus) in an East Mediterranean environment

Abstract Lathyrus sativus L., (grass pea) is an annual plant widely grown as a pulse crop and its dried seeds are harvested and consumed as human food since ancient times. This plant is also commonly grown for animal feed and forage. Grass pea seeds may represent a potential source of several important nutrients for human and animal nutrition. Fatty acid compositions of 173 different grass pea accessions have been studied. Present results indicate that total saturated fatty acids, total monounsaturated fatty acids, total polyunsaturated fatty acids, and total fatty acids ranged from 295.72 to 436.94, 113.19 to 170.78, 127.39 to 179.39, 538.04 to 778.98 mg 100 g−1, respectively. In addition, unsaturated fatty acids, oleic acid, linoleic acid, γ-linolenic acid, and α-linolenic acid that are the main components of fatty acids ranged from 109.22 to 163.95,59.57 to 82.98, 16.18 to 30.38, and 45.56 to 71.59 mg 100 g−1, respectively.