فهرست مطالب ramin rafezi

The main aim of the present research was to evaluate the growth performance and genetic variation in diallel crosses of melon.

To investigate general and specific combining abilities and how genes act in eight melon populations, one-way diallel crosses were performed at Zahak Agricultural Research Station in 2019. Then, parental seeds and hybrids were planted in the spring of 2020 in a randomized complete block design with three replications. Fruit length, fruit width, number of fruits per plant, cavity diameter, fruit weight, total soluble solids, plant length, durability (number of days to crushing), flesh thickness, and yield were examined.

The results of the analysis of variance showed significant differences among the population for all traits. The results of diallel based on method 2 model 1 of a Griffing showed that general and specific combining abilities for the traits are statistically significant at the 5% level of statistical probability. The additive effects of genes on cavity diameter, total soluble solids, and shelf life were observed, expressing the possibility of selection in early generations for these traits. Research limitations: No limitations were founded.

Originality/value: 

The additive effects of genes on cavity diameter, total soluble solids, and shelf life were observed, expressing the possibility of selection in early generations for these traits also durability or shelf life is the most important trait in vegetables especially in melon so, based on these results cross Sefidak × Yellow ivaneki was the best cross for improvement of this trait.

In order to estimate the genetic parameters of resistance against the race 1.2y of Fusarium oxysporum f. sp. melonis, a complete 7 × 7 diallel mating design was conducted with three replications by the use of Iranian native melons including Jalali, Chapalizi, Sooski, Magasi, Khaghani, Semsoori and Shadegani. Moreover two inbred lines including Charentais-T and Isabelle were entered as susceptible and resistant controls in the experiment respectively while they were not involved in diallel mating. Plants were inoculated by root dip method with 106 conidia ml-1 concentration of Maharloo isolate.The traits, including area under disease progress curve (AUDPC), disease severity index (DSI), standardized AUDPC (SAUDPC), and latent period (LP), were all measured. The results revealed significant additive, dominance, and reciprocal variance for all traits followed by significant estimates in broad-sense and narrow-sense heritabilities. The highest narrow-sense heritability was calculated for SAUDPC (0.47). General combining ability (GCA), special combining ability (SCA), and the reciprocal effects were significant for AUDPC, SAUDPC, and LP. Results stand for the significant role of both additive and non-additive effects in the control of the traits. In combining ability studies, Magasi, Chapalizi, and Jalali showed the lowest significant GCA effect for AUDPC and SAUDPC followed by high significant GCA for LP. These populations can be considered as resistant parents in corresponding breeding programs. The F1 of Chapalizi × Sooski showed the lowest significant SCA for DSI, AUDPC, and the highest significant SCA was for LP. Therefore it can be considered as the best resistant ‘hybrid’ against FOM-1.2y.

Plants survive in salinity stress by different mechanisms (Mustafa et al., 2020). Melon is grown in arid and semi-arid regions worldwide especially in where the salinity is a threat. Iran is known as one of major centers of diversity for melon in the world (Pitrat, 2008). There is a wide genetic variation among Iranian native melon landraces. This wide range of diversity can be exploited for increasing drought tolerance in breeding programs. Iran ranks fifth in global melon production (FAOSTAT, 2019). Cultivation of native melons in Iran is offten implemented in the margins of desert areas which have degrees of drought and salinity. Therefore salinity tolerance is known as important factor in melon cropping in Iran. Melon is known as a semi-salt-tolerant plant. Salinity stress causes numerous damages such as irregular growth and developement, metabolic disorders, yield loss and poor flesh quality of Melon. Tolerance of melon genotypes to salinity stress depends on the genetic tolerance of genotypes, environmental factoers like of salinity, and plant growth stage. The most marketable Iranian Melon genotypes are produced in warm and dry weather. According to the classification, Iranian Melon, is one of the plants adapted for semi-saline area (Sobhani & Hamidi, 2014).

This study was carried out in 2019 cropping season in Vegetable Research Center (VRC) of Horticulture Science Research Institute of Iran (HSRI) in factorial were administered in three replications design based on completely randomized block design with six melon genotypes including Durango, Shadegani, Shahabadi, Dargzi, Atashi and Khatouni and five salinity levels including 0, 30, 60, 90 and 120 mmol Sodium Chloride. Melon genotypes was planted in the sand in the greenhouse. The sand was washed three times with tap water and sterilized in 120 °C and 1 bar for 30 minutes. Seeds were sown in about 10 L of sterilized sand in plastic pots. Wet weight of oots and shoots were measured and then placed in the oven at 70 °C for 48 hours to measure the dry weight. Genotypes tolerance to salinity was evaluated by the Van-Hoffman index (Mangal & Hooda, 1988). Germination percentage and relative growth in traits in both wet and dry plant organs were analyzed in factorial statistical method using SAS 9.4. Comparing means of the traits were laied out with Duncan’s Multiple Range Test. All graphs were drawn using Excel 2013 software.

In 30 mmol of salinity, Dorango, Shadegani, Shahabadi, Dargzi, Atashi and Khatouni genotypes, respectively, and in 60, 90 and 120 mmol salinity Dorango, Shahabadi, Shadegani, Dargzi, Atashi and Khatuni genotypes, have the highest germination percentage respectively. Compared to the control (No salinity). Studying salinity tolerance of studied genotypes in vegetative growth stage showed that in 30 mmol salinity Shadegani, Dorango, Shahabadi, Khatouni, Atashi, Dargzi genotypes, respectively, in 60 mmol salinity Shadegani, Durango, Shahabadi, Khatouni, Dargazi genotypes, respectively. Atashi, at 90 mmol salinity, Shadegani, Durango, Khatouni, Dargzi, Shahabadi, Atashi genotypes, respectively, and at 120 mmol salinity, Shadegani, Durango, Shahabadi, Khatouni, Dargzi, and Atashi genotyopes, respectively. Germination was significantly different in the studied genotypes and decreased with increasing salinity level.

This result confirms the results of the similar researchs. Therefore, it is suggested that the salinity level and the proper genotype for that salinity level must be determined for a high yielding marketable fruit production.