Seed and Plant
Year:2000 | Volume:16 | Issue:3|Papers Count:11

Ten maize single cross hybrids were studied for their stability in grain yield, 1000 kernel weight, kernel depth, kernel numbers per row and rows number per ear using regression coefficient (bi), deviation from regression (S2di), stability variance (σ2i), ecovalence(Wi), coefficient of determination (R2), coefficient of variation (C.V.) and simultaneous selection method for grain yield and stability (YSi) indices. The experiments were conducted in Randomized Complete Block Design with four replications at 14 locations for 2 years(1998/99). According to the results, using all stability indices, S2di, σ2i, Wi, R2, C.Y. and YSi, hybrids No. 6(KL17/2-5 x MO17) and No. 10(KSC704) were determined as stable hybrids. The highest grain yield belonged to hybrids No. 6 and ten with 10.346 and 10.362 t ha-1 respectively. The heterogeneity of regression coefficients were significant only for kernel depth and kernel rows number per ear. Grain yield showed positive and highly significant correlation with 1000 kernel weight (r=0.45**), kernel depth (r=0.40**) and kernel numbers per row (r=0.64**). According to the regression coefficients, hybrids No. 6 and No. 10 did not show good response to environmental improvement in term of kernel depth and kernel rows number per ear.  

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.

Formation of reproductive buds, time of flower induction, morphological 0" differentiation and development of the inflorescence and organogenesis of buds in Golden delicious apple trees were studied in the climatic conditions of Khalat Poushan Research Station Tabriz University in East Azarbayejan province. About 50 to 60 spur buds were collected from late June 1993 to mid April 1994 every 10 days. Bud scales and bract primordia were eliminated and then buds were fixed in FAA fixative. After the stages of dehydration and parafin in filteration, embedding, microscopic sections of buds were made stained and studied by the microscope. Results of investigation and study of microscopic sections showed that flower induction in bud meristems occurred during mid July to early August, and first morphological development was observed in induced meristems in mid August. Subsequently organogenesis occurred in terminal bud flower of florescence. Sepal primordia was formed in late August, petal primordia in early September, and eventually stamen primordia developed in mid September. The organs developed gradually. The carpel primordia of the terminal flower was formed late in winter (March). Organogenesis stages in lateral flowers of inflorescence occurred few days after formation of later than terminal flower. Final development of these organs accrued rapidly in early spring and a complete inflorescence was observed in mid April.

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

Wheat yellow rust (Puccinia striiformis) is one of the most important fungal diseases of wheat in Iran. Identification of resistance genes and their mode of action is important in utilization of resistance sources and the breeding strategy adopted in a breeding program. In this study, four resistant parents and one susceptible cultivar were used in a diallel fashion excluding reciprocals. Parents and the Fl progenies were inoculated at seedling stage (First leaf) with pathotype 230E245A+ of Puccinia striiformis. Latent period, defined as days from inoculation to first pustule appearance was daily recorded from the first appearance of pustules up to 25 days after inoculation. Entries without pustule formations were given a score of 25. Results of inheritance studies using Hayman and Griffing methods indicated that addative components and complete dominance played major roles in conditioning latent period in these ten crosses. Broad-sense and narrow-sense heritability estimates for latent period were 0.99 and 0.88, respectively. The results suggested that considerable progress may be expected for latent period in a breeding program.

In order to study the effects of salinity and nitrogen nutrition on rate of free- praline in the leaves, and effect of salinity on seed oil content of common pumpkin (Cucurbita pepo subsp pepo var. styriaca), the field and greenhouse studies were conducted in Tarbiat Modarres University in 1998 and 1999 cropping seasons. For salinity and nitrogen nutrition effects on rate of free-proline in the leaves, the experimental design was split-plot with RCBD arrangement in three replications in which salinity treatments at four levels (0,2.5,5 and 10 grl-1 of NaCl) were considered as main plots and nitrogen treatments at five levels (0, 75, 150, 225 and 300 kg ha-1 of NH4 N03) as sub-plots. However, for salinity effect on oil content of seed, the experimental design was RCB with three replications. Salinity stress was applied at two stages i.e. by soaking the seeds in the solution for 36 h before planting, and during stage from four leaves until flowering. Meanwhile, nitrogen fertilizer was applied to the plants at three stages (planting, four leaves stage and t1owering). Results indicated that in both years of the experiment, salinity stress increased the amount of free-proline in the leaves compared to the check. The highest rate of proline was obtained when salinity and nitrogen levels were at 2.5 grl-1 and 225 Kgha-1, respectively. The highest oil content in seed was also obtained at salinity of 2.5 grl-1 of NaCl.

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 δ 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.