Breeding of Nutty Watermelon (Citrullus lanatus (Thund) Matsum and Nakai) Evaluation and Selection from among the Populations of some Landraces

Document Type : Research Article

Authors

• K. Hokmabadi ¹
• S.H. Nemati ¹
• R. Tavakkol Afshari ²

¹ Department of Horticultural Science and Landscape, Ferdowsi University of Mashhad, Mashhad, Iran

² Department of Agrotechnology, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran

https://doi.org/10.22067/jhs.2025.90646.1390

Abstract

Introduction
The success of breeding programs depends on the existence of diversity in germplasms in terms of the desired trait or traits. Collecting superior watermelons and examining their characteristics provides valuable resources to researchers for breeding programs. Watermelon (Citrullus lanatus (Thund) Matsum and Nakai) (Citrullus lanatus) has great diversity in terms of shape, fruit size, fruit skin pattern, fruit flesh color, seed length and width, and number, the seed in the fruit as well as the quality of the fruit is among its cultivars and varieties, therefore it seems that by examining the native cultivars it is possible to find desirable traits and use them in future commercial cultivars for breeding processes. Iran is the most important producer of watermelon seeds. These nuts not only meet the needs of the domestic market, but are also one of the export items, especially to Arab countries. Limited breeding efforts have been made globally on nutty watermelons. However, developing high-yielding and high-quality cultivars can improve water use efficiency and enhance export potential and foreign exchange earnings. In many central and eastern provinces of the country, nutty watermelons are commonly cultivated as a second or dry-season crop. Unlike edible watermelons, the yield in nutty watermelon cultivation is measured by the quantity of dry seeds produced, rather than the fresh weight of the fruit, as the seeds are harvested for use as snacks. The primary breeding objective for nutty watermelons is seed yield. Other key traits targeted for improvement include larger seed size, a higher kernel-to-hull ratio, and softer seed texture.  Therefore, due to the fact that it is necessary to investigate the cultivated landraces in each region, the genetic diversity and capabilities of each for genetic modification and improvement should be determined. This research investigates the genetic diversity of the indigenous s of Iran through the investigation of morpho-physiological traits.
 
Materials and Methods
In order to evaluate genetic diversity and eliminate weak and low-quality landraces in the first generation and to investigate genetic improvement in the second generation of 10 Iranian watermelon (Citrullus lanatus (Thund) Matsum and Nakai) landraces by examining growth and seed-related traits, a two-year study was conducted in Farouj County. Seeds of the landraces Jabani (4 lanrace), Sanbak (4 landrace), and Kalaleh (2 landrace) from Jovin, Kashan, and Gorgan were separated and collected based on fruit skin color and seed-related traits. Direct seed sowing was carried out in Farouj County lands using drip irrigation with a tape. Evaluation of 10 local breeds was carried out in the first year (first generation) in a randomized complete block design with 3 replications and 10 samples per experimental unit. Then, inter-cultivar and intra-cultivar selection was carried out among the 10 local breeds with regard to uniformity and especially data on key seed-related traits, including seed yield and kernel-to-seed percentage. The 4 selected landraces from the first year were evaluated again in the second year (second generation) in a randomized complete block design with 3 replications and 10 samples in the experimental unit.
 
Results and Discussion
Data analysis of the selected landraces  in the first and second years was performed as a split plot analysis of variance. The study of morpho-physiological and functional changes of different watermelon s in the first generation showed that the s of Stigma 1 and 2 and Jabani 1 and 3 were superior to the other landraces in terms of growth traits and fruit yield, but in the second generation, Jabani 1 had the best fruit yield in terms of weight and fruit flesh percentage and can be used as mother s for the improvement of nut watermelon. Also, in the first generation, the study of traits determining seed quality and quantity such as thousand-seed weight, percentage of kernel weight to seed, length, width and diameter, and seed coat thickness showed that Jabani 1 and 3 were the most desirable landraces. In the second year, the Jabani 1 and 3 landraces had the highest seed quantity and quality and were suitable for cultivation as nut watermelons. Comparison of the two generations of each of the selected landraces showed that most of the fruit and seed traits improved under the influence of generation, and the second generation produced heavier fruits with higher seed yield. Also, this improvement in fruit traits in Jabani 1 and improvement in seed traits in Kalaleh 1 was more significant than in others.
 
 
Conclusion
The evaluation of morpho-physiological and functional traits in the first generation of various watermelon cultivars revealed that Kalaleh 1 and 2, along with Jabani 1 and 3, outperformed the others in terms of growth performance and fruit yield. However, in the second generation, Jabani 1 demonstrated the highest fruit yield, particularly in terms of fruit weight and flesh percentage, making it a strong candidate for use as a maternal parent in nutty watermelon breeding programs. Additionally, the assessment of seed quality and quantity traits—such as thousand-seed weight, kernel-to-seed ratio, seed length, width, diameter, and shell thickness—in the first generation indicated that Jabani 1 and 3 were the most desirable cultivars. In the second year, Jabani 1 and 3 exhibited the highest seed quantity and quality, making them well-suited for cultivation as nutty watermelons. A comparison between the two generations of each selected cultivar revealed that most fruit and seed traits improved in the second generation, which produced heavier fruits with enhanced seed yield. Notably, improvements in fruit-related traits were most significant in Jabani 1, while enhancements in seed-related traits were more pronounced in Kalaleh 1 compared to the other cultivars.

Keywords

• Fruit
• Genetic diversity
• Genetic improvement
• Seed
• Yield

Main Subjects

• Growing vegetables

©2025 The author(s). This is an open access article distributed under Creative Commons Attribution 4.0 International License (CC BY 4.0).

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