نشریه نهال و بذر
سال شانزدهم شماره 3 (پاییز 1379)

In order to study the effects of agronomic traits on grain yield of wheat and determine the best criteria for selection of high yielding and adaptable genotypes in cold dryland areas, 385 advanced wheat genotypes were evaluated in Dryland Agricultural Research Institute (DARI) at Maragheh in 1997-98 cropping season. Nine experiments, each with 24 lines in RCBD with four replications and one preliminary yield trial in simple lattice design with two replications were conducted. Results showed highly significant differences for grain yield, days to heading, days to maturity, plant height and 1000 kernel weight among the lines. The classification of genotypes for days to heading indicated that the highest grain yield was obtained from the early heading group with average grain yield of 1790 k ha-1, and the lowest grain yield was harvested from the very late heading group with 710 k ha-1. The classification of genotypes for plant height indicated that tall and early heading genotypes produced higher yield than the short and late heading genotypes in rainfed areas. The results also showed that correlation coefficient between days to heading and plant height was negative and significant (r=-0.30*) in the late heading groups. In early heading group, plant height had positive and highly significant correlation (r=0.57**) with grain yield which indicated the importance of selection for earliness and tallness in dryland areas. Meanwhile, high and low 1000 kernel weight were obtained from early and late heading group, respectively. The classification of genotypes for growth habit, indicated that winter types had higher yield, higher plant height, higher 1000 kernel weight, and also had more tolerance to cold than facultative and spring types. Overall, the results of this study revealed that, the selection of earliness, winter type and high plant height could increase grain yield in wheat improvement program in cold dryland areas.

Iranian onions have good characteristics, but in some of them the yield is lower than F1 cultivars. For this reason, production of hybrid seeds is important. There are many ways for producing inbred lines, but gynogenesis offers the possibility to produce homozygous plant in very short time whereas traditional method takes long time. The aim of this research was to study the responses of six Iranian onion populations, Ghermez-e-Azarshahr, Sefid-e-Kashan, Sefid-e-Kamare-e-Khomain, Sefid-e-Qom, Dorcheh-e-Esfahan, Gholigheseh-e-Zanjan, and two Italian cultivars, Borettana and KLR (used as control) to in vitro gynogenesis on two F6 and JAP media with two replications. The results showed significant differences (P < 0.05) between the two media on percentage of embryo rate, percentage of callus formation and percentage of hyper hydrated flowers and a high interaction (P < 0.05) between media and cultivars. F6medium in comparison with JAP medium had more embryo and callus formation and hyper hydrated flowers. The highest percentage of embryo was produced by Gholigheseh-e-Zanjan onion, while the lowest by Sefid-e-Kamare-e-Khomain.

In order to study the effects of Vesicular Arbuscular Mycorrhizae (VAM) fungi, phosphorus and drought stress on nutrient uptake efficiency in wheat, 3 factors of Mycorrhizae (with and without application), phosphorus (0, 6 and 12 g P2O5 per m2), and irrigation (10.5, 24.8, 36.1, 46.2 and 55.1mm water for each irrigation interval) were investigated on wheat (Mahdavi cultivar) with 3 replications based on Hanks et al. (1980). Application of fungus caused a significant increase in phosphorus and potassium uptake efficiency. The effect of phosphorus on above character was also significant at the 1% level of probability. There was not significant difference between application and non-application of fungus in nitrogen uptake efficiency, whereas application of different levels of phosphorus caused a significant difference at the 1% level on this character. Mean comparison of effects of fungus x phosphorus x irrigation on phosphorus uptake efficiency showed that symbiosis of phosphorus, had most phosphorus uptake efficiency (428.7gkg-1). The highest phosphorus uptake efficiency (295 gkg-1) without application of VAM fungi was obtained by use of 55.1 mm water for each irrigation interval and application of 6g P2O5 per m2.Therefore VAM fungi caused a significant increase for phosphorus uptake efficiency in low phosphorus levels.

An experiment was conducted in order to study the effective components on grain weight and effects of some physiological parameters on grain yield of spring wheat genotypes under optimum and post - anthesis drought stress conditions. Sixteen genotypes were studied in eight replications. Four replications were irrigated regularly but in other four replications no irrigtion was applied from anthesis to physiological maturity. Grain yield (GY) as well as the amount, percentage and contribution of remobilization, retranslocation, and redistribution were determined in different treatments. The contribution of current photosynthesis was calculated based on main sources which provide grain weight. Photosynthesis to redistribution ratio, biological yield (BY), harvest index (HI), grain growth rate (GGR), effective grain filling period (EFP) and stress tolerance index (STI) were also determined. Results showed that correlations of grain weight with BY and GGR were positive and highly significant, while correlation between GGR and EFP was negative and highly significant. Under optimum and stress conditions, correlation between remobilization and current photosynthesis and under stress condition, correlation between remobilization and retranslocation were negative and highly significant. Only HI was significantly correlated with STI in stress condition2. Stepwise regression analysis revealed that BY and HI were the most Important components of grain weight. Correlation analysis based on all data showed that current photosynthesis and remobilization were the most effective physiological parameters of grain weight.

Tomato is the most important agricultural crops in Bushehr province. This experiment was conducted on a Randomized Complete Block Design (R.C.B.D.) with 15 treatments cultivars and 4 replications in the Borazjan Research Station during two consecutive cropping seasons (1995-97) to find tomato cultivars with high yield and quality and suitable for the region. Cultivars had been selected among 60 cultivars and lines from the previous years preliminary yield trails carried out in 1993-94. Cultivars were planted in the furrows with spacing 110 x 50 cm. Highest yields (Table 1 in Farsi text) were obtained from Sp.99 (40.15 tha-1), L-519 (Calj hyb 579, 36.42 tha-1) and L-81 (Koral, 35.97 tha-1) so they are recommonded for Bushehr province.

Yekta was created in 1981 from crossing between B5 ? M7 and an early maturing Palistinian line, in Oil Seed Crops Research Department of Seed and Plant Improvement Institute (SPII) at Karaj. The pure line of the cross was obtained after five years of selection with pedigree method. Preliminary evaluation of the line along with other 31 selected lines was done in 1989 and Yekta together with other 13 advanced lines were selected and further evaluated for two more years started in 1990.Results showed that Yekta with average yield of 1955 kgha-1 was superior to the check cultivar and other lines in the trial. In advanced yield trial which was conducted in Karaj, Sari and Moghan from 1990 to 1992, Yekta with average yield of 1331 kgha-1 was found as a superior and stable line. This cultivar is early in maturity and recommended for northern parts of Iran with altitude of more than 1000 meter abave the sea level and for the areas with short growing season that the late maturing cultivars of sesame usually do not perform well.