نشریه نهال و بذر
سال سی و هفتم شماره 3 (پاییز 1400)

Bread wheat is one of the most important food crops that is grown in different climatic conditions across the world. One of the important factors for this wide adaptability is the role of vernalization genes in different wheat genotypes. Therefore, identification of allelic variations of these genes provides an opportunity to determine growth habit, prediction of cold tolerance and adaptability of bread wheat genotypes to different climatic conditions. In this study, growth habit of 40 promising bread wheat genotypes was evaluated in the field and glasshouse during two and one cropping seasons, respectively. Allelic variation in VRN-1 and VRN-3 loci was also determined using nine locus-specific primer pairs. In VRN-A1 locus; Vrn-A1a, Vrn-A1b, Vrn-A1c and vrn-A1 alleles had frequencies of 7.5%, 7.5%, 10% and 67.5%, respectively. In this locus, three genotypes did not produce any band. In VRN-B1 locus; dominant and recessive alleles had frequencies of 52.5% and 47.5%, respectively, and in VRN-D1 locus; dominant and recessive alleles had frequencies of 60%, 40%, respectively. In VRN-3 locus; the majority of genotypes (97.5%) had recessive allele (vrn-B3). Results of this study indicated that different alleles of VRN-A1 locus had more influence on field growth habit as compared to VRN-B1 and VRN-D1 loci, and different combinations of these alleles resulted in range of various field growth habits from true spring to true winter. The results of this study can be used in the national bread wheat breeding programs for pyramiding favorite alleles of vernalization genes to improve adaptability of bread wheat genotypes for different target agro-climatic zones of Iran.

To identify and select superior walnut genotypes with lateral bearing, a portion of walnut germplasm of Urmia region was priminarily evaluated in 2018 and 2019. Eleven superior genotypes were selected and along with Chandler cultivar, as control, were evaluated for pomological, biochemical and fatty acids properties. Some to nut and kernel related traits, total phenol and flavonoid contents and antioxidant activity, oil content and fatty acid profile were studied. Nut and kernel weight varied from 9.1 g (PG7) to 15.36 g (PG6), and 5.03 g (PG5) to 6.73 g (PG6), respectively. The highest kernel percentage with the lowest thickness of hard shell was observed in PG7 which was significantly higher than cv. Chandler. The highest total flavonoid content and antioxidant activity observed in cv. Chandler. For all studied genotypes, except PG2, fat content was higher than 55%. Eight fatty acid compounds were identified in walnut oil of which the highest content belonged to linoleic acid, oleic acid and linolenic acid, respectively. The highest linoleic acid (47.78%) and linolenic acid (21.73%) content was observed in PG6 genotype. The results showed that there were very desirable genotypes among the selected walnut genotypes which were competitive to cv. Chandler in respect of some quantitative charcteristics and quality properties of nut and kernel.

Androgenesis has great potential in plant breeding due to its high efficiency and applicability in many plant species. Anther culture is one of the most common technique to induce haploids in plant breeding programs. In this study, to optimize anther culture of bell pepper, the effects of four darkness periods and five concentration levels of silver nitrate were studied in four commercial hybrids; Kamelot, Inspiration, Plato and Californium. The results showed that increasing dark treatment from six to ten days, increased the percentage of embryogenic anthers and the percentage of regenerated plantlets. The highest percentages of embryogenic anthers and regenerated plantlets were obtained using 10 mg l-1 of silver nitrate and incubating anthers cultured in CP medium for 10 days in darkness. The results also showed that the highest percentage of embryogenic anthers (16.66%) was observed in the interaction effect between 10 mg l-1 of silver nitrate and cv. Plato. Also, among the studied concentrations of silver nitrates, the highest percentage of regenerated plantlets (11.71%) was obtained using 10 mg l-1 of silver nitrate.

This study was conducted to investigate the effect of sowing date on grain yield and agronomic charcteristics and to determine the optimum sowing date for new bread wheat cultivars in the warm and dry agro-climatic conditions of Fars provienc. The experiment was carried out as split plot arrangements in randomized complete block with three replications at Darab agricultural research station in 2018- 19 and 2019-20 cropping seasons. The main plots consisted of five sowing dates; 27 October, 11 November, 26 November, 11 December and 26 December, and the sub-plots included five bread wheat cultivars; Mehergan, Barat, Khalil, Sarang and Setareh. The highest and lowest mean grain yield obtained from 11 November (6930 kg ha-1) and 26 December (5770 kg ha-1), respectively. The relatively late cultivar; Khalil had higher grain yield than other cultivars in early sowing dates. The early cultivars; Setareh and Mehregan had higher grain yield in latest planting date (26 December) compared to the earliest planting date (27 October). Sarang cultivar with a mean grain yield of 6650 kg ha-1 had the lowest yield variation in the studied sowing dates. The recommended sowing date window and the optimum sowing date were different for each cultivar and varied from November 16 to December 16. These results indicate that the selection of early cultivars is very effective factor in integrated crop management for reducing grain yield losses due to delay in sowing date in warm and dry regions of Fars province and similar agro-climatic conditions in Iran.

In recent years shortage of water and necessity of forage production have led to a tendency towards low-input plants such as Kochia. Kochia, that plant that, in addition to drought and salinity tolerance, have the potential to produce forage in less favorable environmental conditions. To evaluate forage yield and quality of Kochia as affected by drought stress, plant density and harvesting stage a field experiment was conducted in 2020 and 2021 at the Jupar agricultural research rtation of Kerman. The experiment was carried out as split plot factorial arrangements in randomized complete block design with three replications. Drought stress at three levels; irrigation at 50%, 70% and 90% depletion of soil available moisture were assigned to main plots and two planting density; 33.3 and 16.6 plant m-2 and two harvesting stages; vegetative growth stage (55 days after emergence) and flowering stage as factorial were randomized in sub plots. In irrigation at 50% and 90% soil available moisture depletion dry forage yield was 7.15 and 6.45 ton ha-1, respectively, however, this difference was not significant. Harvesting at the flowering stage with production of 31.30 ton ha-1 of fresh forage and 8.96 ton ha-1 of dry forage was significantly superior in comparison with other treatments. The highest amount of forage protein (10.94%), and the lowest amount of NDF (%50.6) and ADF (%33.8) were obtained in the severe drought stress (90% depletion of soil available moisture). Harvesting at the flowering stage had lower protein and higher NDF than vegetative growth stage. The results of this study indicated that it is possible to produce 4.5 ton ha-1 of dry forage by harvesting at vegetative growth stage and 8.5 t ha-1 of dry forage at the flowering stage by application of irrigation at 70% to 90% soil available moisture depletion.

To estimate general and specific combining abilities and heritability in potato genotypes diallel analysis based on Griffing method was used. Reciprocal crosses were made between four commercial potato cultivars; Savalan, Luca, Satina and Caeser parents. For crosses and preliminary tuber seed increase carried out at greenhouse, and main gentypic evaluation trial was performed in field at Alarouq research field station during 2016-2019. There were significant differences between genotypes for tuber yield, tuber number and weight plant-1, main stem number plant-1, plant height, mean of main stem diameter, and tuber dry matter content. General and specific combining ability of tuber yield, tuber weight per plant and plant height were significant. The highest positive and significant general combining abilities for tuber yield, tuber weight plant-1 and main stem number plant-1 belonged to cv. Luca and cv. Savalan. The highest positive and significant specific combining ability for tuber yield was observed for ♂Savalan×♀Luca, ♂Satina×♀Luca, ♂Caeser×♀Luca, ♂Caeser×♀Savalan, ♂Luca×♀Caeser and ♂Savalan×♀Caeser. Tuber yield, tuber weight plant-1, plant height, main stem number plant-1 and tuber dry matter content had higher general heritability.