BIODIVERSITAS ISSN: 1412-033X Volume 23, Number 4, April 2022 E-ISSN: 2085-4722 Pages: 1813-1821 DOI: 10.13057/biodiv/d230413 Half diallel of F1 tomato hybrid and its double cross-compatibility MUH FARID ♥ , MUHAMMAD FUAD ANHSORI ♥♥ , IFAYANTI RIDWAN, NOVATY ENY DUNGGA, IRNA ERMIYANTI Department of Agronomy, Faculty of Agriculture, Universitas Hasanuddin. Jl. Perintis Kemerdekaan Km. 10, Makassar 90245, South Sulawesi, Indonesia. Tel.: +62-411-586014, ♥ email: farid_deni@yahoo.co.id; ♥♥ email: fuad.pbt15@gmail.com Manuscript received: 19 November 2021. Revision accepted: 17 March 2022. Abstract. Farid M, Anhsori MF, Ridwan I, Dungga NE, Ermiyanti I. 2022. Half diallel of F1 tomato hybrid and its double cross- compatibility. Biodiversitas 23: 1813-1821. Breeding program for improvement of tomato fruit can be done through diallelic crosses genetic combinations. Therefore, genetic evaluation is needed to meet the breeding objective. This process can be combined with crosses between F1 to produce high diversity. However, evaluating the crosses' compatibility is required to increase the effectiveness of the assembly process. This study aimed to assess the half-diallel crosses of F1 tomatoes in the field and determine the most compatible pair cross combinations in forming double and three-way F1 populations. This study was carried out in the Experimental Farm of the Faculty of Agriculture, Hasanuddin University. The field evaluation was arranged in a randomized complete block design with ten genotypes, while the compatibility evaluation was carried out using 6 F1 half diallel as the parents. The results showed that the Mawar and Chung varieties were better parents in the crossings. Furthermore, the results showed that F1 K/M (the best yield component), M/C (the best TDS and Lycopene traits), and BC/K (the genotype has good traits of yield component, TDS and Lycopene) were the best single F1 crosses that could be inherited to the F2 generation. In contrast, F1 K/M and F1 K/C crosses were the best male and female parents, respectively. The recommended double-crosses include K/C//BC/M, and BC/C//K/M, while for the F1 unbalanced three-way cross was K/C//K/M. Keywords: Compatible ability, diallel mating, double-cross, hybrid tomato, Solanum lycopersicum Abbreviations: BC: Blackcherry, C: Chung, K: Karina, M: Rose, FD: fruit diameter, FL: fruit length, TDS: total dissolved solids, FW: fruit weight, L: lycopene, NBP: number of bunches per plant, NFB: number of flowers per bunch, NFpB: number of fruits per bunch, SD: stem diameter INTRODUCTION Tomato (Lycopersicum esculentum Mill) is one of the food products that are rich in natural antioxidants. It has good antioxidant content, specifically lycopene, which improves the immunity of the human body (Elbadrawy and Sello 2016; Fraser et al. 2020; Przybylska 2020). The antioxidant content in tomatoes has a variety of health benefits and diverse nutritional content such as fiber, carbohydrates, vitamins, minerals, and protein and fat (Raiola et al. 2015; Leiva-Brondo et al. 2016; Campestrini et al. 2019). These benefits have made the fruits highly demanded by the public (Fentik 2017; Chaudhary et al. 2019). However, the growth of tomatoes production is considered slow. According to the statistics of Indonesia (2021), the average growth increase of this fruit is 5.13%. Therefore, developing the productivity and quality of tomatoes in line with the population rate is one of the keys to stabilizing the rate of production and demand. One of the main problems of tomato cultivation in Indonesia is the lack of high-yielding superior varieties with good fruit quality and resistance to pests and diseases (Suyadi and Rosfiansyah 2017; Schreinemachers et al. 2018; Piosik et al. 2019; Oliveira et al. 2020; Afifah et al. 2021). Therefore, efforts to obtain superior varieties need to be carried out, both with conventional and breeding methods such as crosses (Holme et al. 2019; Campanelli et al. 2019; Avdikos et al. 2021), mutation breeding, and genetic engineering (Ayenan et al. 2019; Chaudhary et al. 2019; Cappetta et al. 2020; Afifah et al. 2021; Breitel et al. 2021; Salava et al. 2021). In addition, due to the various benefits of tomatoes, more improvement needs to be carried out on the plant in terms of productivity, fruit quality, resistance to plant pest organisms, and tolerance to various environmental stresses (Acquaah 2012). Therefore, the plant crosses are required to obtain adaptive and high- quality tomatoes that meet consumers' preferences. Furthermore, according to Mustafa et al. (2019), the assembly of different varieties through crossing can induce the dominant and overdominant gene action based on the desired traits. This gene action would be able to create lines that are better than their parents and be effective in improving the crop. The crossing methods strongly influence the formation of tomato diversity. Examples include single, double, three- way, multiple, backcrosses, and diallel mating. Diallel mating is a crossing technique that creates a high diversity of crosses (Olfati et al. 2012; Zeinab and Helal 2014; Murtadha et al. 2018; Mat et al. 2020). This high diversity serves as an equal opportunity for each parent to be crossed with each other; hence, the number of possible crosses can be the combinatorics of all the parents involved (Olfati et