To study the effect of plant density and planting arrangement on yield and bulb size of two onion cultivars, a filed experiment was carried out as split factorial arrangement in randomized complete block design with three replications in the research field of Seed and Plant Improvement Institute, Karaj, Iran, in 2018-2019. Two onion cultivars, Morvarid and Zargan, were assigned to main plots, and inter row spacing of 10, 15, 20 cm and intra row spacing of 5, 7. 5, 10, 12. 5 cm as factorial were randomized in sub plots. Cv. Morvarid and cv. Zargan had the highest marketable yield in 15 × 7. 5 and 15 × 10 cm planting arrangements (88. 8 and 66. 7 plant m-2, respectively) with 73. 7 and 67. 6 t ha-1, respectively. In cv. Morvarid and cv. Zargan, with decreasing the plant density, the proportion of small bulbs decreased from 38. 31 to 6. 57% and from 64. 12 to 7. 77%, respectively. In cv. Morvarid, with decreasing the plant density, large bulbs, doubles and thick neck bulbs increased from 3. 19 to 19. 85% and from 7. 92 to 29. 41%, respectively. In cv. Zargan, with decreasing the plant density to 66. 7 plant m-2 (15 × 10 cm), the proportion of medium size bulbs increased from 35. 87 to 80. 15%. During the storage period, cv. Morvarid had lower percentage of bulb sprouting and decay than cv. Zargan in all planting arrangements. The results of this research showed that in cv. Morvarid and cv. Zargan, planting arrangements of 15 × 7. 5 cm and 15 × 10 cm, respectively, could be recommended to onion producers, because less seedlings are required for transplantation when compared with higher plant densities.

In order to compare the storability of short day onion populations and cultivars in non-controlled storage, this research was conducted at Behbahan Agriculture Research Station from 2013 to 2014 for two years. Seeds were sown in nursery in late September. Seedlings were transplanted at 2-3 leaf stages. Evaluation of bulb storability was performed by using split plot experiment based on RCBD with four replications. Main plot consisted of eight populations and cultivars (Behbahan, Padook, Ramhormoz, Iranshahr and Brazjan landraces, Primavera and Texas Early Grano cultivars and improved population of Behbahan onion) and six storage times (1, 2, 3, 4, 5 and 6 months) considered as sub plots. The monthly bulb loss weight percentage decreased with passing time. Improved population of Behbahan onion had the most sever weigh losses (20. 26%). Damage of black mold increased until the third month of storage and then decreased. Ramhormoz landrace was the most sensitive genotype damaging from black mold (39. 47%). The highest percentage of bulb rotting (29. 65%) was recorded for Primavera cultivar and storability of this cultivar was significantly lower than other genotypes. bulb sprouting was observed from the third month of storage. Iranshahr landrace had the highest bulb sprouting (31. 57%). Results showed that according to storability, improved population of Behbahan onion and Texas Early Grano were better than other genotypes.

A factorial experiment was conducted to determine the effects of different doses of gamma irradiation on postharvest life and quality of bulbs of four Iranian onion cultivars (White-Ghom, White-Neyshabour, Red-Ridge-Lump, Red-Ray-Corrugated) during 120 days storage at 10-15 °C and 70% relative humidity. Interactive effects of cultivar and irradiation dose significantly affected sprouting, weight loss, firmness, soluble solids content (TSS), and contents of reducing sugars and pyruvic acid (PA) of the bulbs after 120 days of storage. sprouting of the bulbs ranged between 10-100%. The untreated bulbs showed the highest sprouting and weight loss. Gamma irradiation (30-150 Gy) significantly restricted the sprouting percentage and decreased bulb weight loss. Firmness of the irradiated bulbs (90-150 Gy) was higher than the control bulbs. Weight loss of the bulbs was positively correlated with sprouting and negatively correlated with bulb firmness. The irradiation treatments increased the TSS (30-150 Gy) and a reduction in the sugar content of the bulbs (60-150 Gy). The untreated bulbs had the lowest PA content at the end of the experiment. Exposure to 90-150 Gy irradiation doses resulted in the highest PA content in the bulbs. In summary, the application of 90 to 120 Gy of gamma radiation for improving post-harvest shelf life and quality of onions can be considered as a general guideline.

In order to recognize and select Iranian onion cultivars with the best quantitative and qualitative characters such as yield, neck thickness, size, form, number of scales, storability, dry matter, total soluble solid, firmness and determine the relation of some characters on storability, this experiment was conducted at Karaj in 1999-2000. Field experiment was carried out based on Randomize Complete Block Design with four replications and five treatments Ghermez Azarshahr, Sefide Kashan, Sefide Qhom, Tarom Zanjan and Dorche Isfehan onion cultivars. For determination of the storage ability of Onion cultivars, a study was carried out in a factorial experiment based on completely randomized design with three replications in common storage conditions. Factors were cultivars with five levels and dates with eight levels. In a period of four months at 15 days interval, (8 distinct dates) losses were measured according to percentage of weight loss, sprouting and rotting. The rate of changes of some traits such as total soluble solids (T.S.S), dry matter (Dm), bulb firmness were also determined during storage. Results showed that in field experiment, the highest and lowest yields were obtained from Sefide Qum cultivar (60.82 tha-1) and Dorche Isfehan (32.03 tha-1) respectively. Sefide Qum cultivar had the lowest percentages of weight loss, sprouting and rotting during storage (15.33% and 11.72% respectively), which were not significantly different from those of Germez Azarshahr and Dorche Isfehan. Tarom zanjan cultivar had the highest weight loss, and Sefid Kashan had the highest bulb sprouting and rotting during storage period (23.06% and 55.46%, respectively). In storage period, some qualitative characters such as dry matter and total soluble solids increased slightly, but bulb firmness decreased. Sefid Qum cultivar had the highest total soluble solids, dry matter and bulb firmness (9.81%, 11.8%, 39.19 N, respectively), and Tarom Zanjan the lowest (8.37%, 9.29%, 34.3 N, respectively). A highly significant positive correlation (r =0.84) and linear regression equation (y = -2.472 + 1.424x) was found between total soluble solids and dry matter of bulbs. During storage, a significant negative correlation of (r = -0.592) and linear regression equation (y=101.515-1.863x) was found between bulb firmness and sprouting and rotting.

This experiment was conducted for two years to study post–harvest bulb losses of onion genotypes in uncontrolled storage (no heating, cooling and ventilation systems) at Behbahan Agriculture Research Station. Seeds were sown in nursery in early October and seedling transplanted at 2-3 leaf stage. bulbs were harvested when 50-80% of foliage top had fallen and collapse. The research was performed using split factorial experiment based on RCBD including 120 treatments with 3 replications. Main plot consisted of six bulbs observation in storage (one months after storage with one month interval). Sprayed and non-sprayed plots and ten onion genotypes named Behbahan, Padook, Ramhormoz, Iranshahr, Borazjan ,Dorcheh Esfahan, and Kamerei Khomain landraces, Primavera and Texas early grano cultivars and improved population of Behbahan onion were considered as factorial. Thrips increased bulb weight losses, damage of black mould and total losses. The damage of bulb rotting decreased in non- sprayed plots as compared with sprayed plats. The effect of thrips was not significant on bulb sprouting. The minimum bulb weight losses and damage of black mould were recorded in Primavera cultivar and Behbahan improved population respectively. The lowest bulb rotting was observed in Ramhormoz landrace. The highest bulb sprouting was found in Iranshahr landrace. According to results, Texas early grano cultivar and Dorche Esfahan landrace, showed the maximum and minimum bulb storability respectively.

This study was carried out to appreciate forcing and reduce the glasshouse period of Narcissus flower ‘German’ production. Experiment was performed in Faculty of Agricultural Sciences, the University of Guilan, in 2006. The experiment was conducted as a factorial in a completely randomized design.  with 8 treetments and 3 replications. Treetments include temperature (Control and 4°C) and gibberellic acid (GA3)Tat 0, 200, 400, 600 mg l-1 cincentrations. The parameters such as sprouting time, day to flower stem emergence, flowering time, flower stem length, stem diameter, leaf length,  leaf number, number of floral bud, number of vegetative bud, bulb diameter and bulb weight were measured. The results indicated that bulb exposure to low temperature accelerated sprouting, flower stem emergence and flowering. Leaf length, stem diameter and stem length were also increased. GA3 at the concentration of 600 mgl-1 had significant effects on shoot growth (leaf and stem quality) and sprouting when compared with other concentrations.

This research evaluated the effects of onion curing methods on the qualitative traits of Iranian onion cultivars (Azarshahr Red, Neishabour Red, Kashan White, Qom White). Testing was carried out in the autumn and winter of 2007. The experimental design was factorial with two factors and three replicates. The factors were traditional and sunlight curing methods at 42oC for 12 hr for 48oC for 4 hr and four onion cultivars. bulb qualitative traits of firmness, sprouting percentage, total soluble solids content, vitamin C content and pyruvic acid content (pungency index) were recorded after four months storage. Results showed that onions stored using the different curing methods showed significant differences in firmness, weight loss, sprouting, vitamin C and pungency rate. Kashan White, Neishabour Red and Qom White demonstrated higher firmness. bulbs cured at 42oC in sunlight had a higher rate of sprouting compared to those stored at 48oC. Pyruvic acid content in the sunlight method was higher than for the other method; the percentage of vitamin C was higher for onions cured at 42oC. Qom White onions cured solely in sunlight produced fewer losses and suitable quality traits, thus, this treatment is recommended.

Pre-harvest sprouting is one of the main factors that reducing the rice grain yield and quality in humid weather condition with raining at harvest time. Thirty four local and improved rice cultivars were evaluated for pre-harvest sprouting and some related characteristics to this trait at in vivo condition. Analysis of variance results indicated that the differences between rice genotypes were significant for pre-harvest sprouting and some other traits of grain. Genotypic and phenotypic correlation coefficients of pre-harvest sprouting with alpha amylase activity were positive, this result showed that the alpha amylase activity had significant effect on pre-harvest sprouting. All rice cultivars classified into three groups by cluster analysis using ward method. First group included 24 cultivars and second and third groups included 4 and 6 cultivars respectively. In total, cultivars of the first and third groups had the lowest of pre-harvest sprouting rate, so they were resistant to germination before harvest and the cultivars of second group had the highest of pre-harvest sprouting rate, so they were sensitive to germination before harvest. Results of this experiment showed some local rice cultivars such as Domsefid and Hashemi, with high resistance to pre-harvest sprouting could potentially be used in breeding programms.