Abstract This study reports an induced physical mutation by gamma irradiation on a local sweet orange variety in order to develop new seedless varieties. Mature autumn shoots of seedy ‘Kozan’ common orange (Citrus sinensis (L.) Osb.) trees were irradiated with gamma rays from 60Co. The survival rate was 65 % for the dose of 60 Gy irradiation treatment of ‘Kozan’ common orange. In order to stabilize the mutation, mV3 plants were developed by re-budding and plants at mV3 generation were transplanted in the orchard in 2016. Observations in the present study were recorded for three consecutive years and trees which produced a sufficient number of fruits were evaluated for 19 fruit quality characters such as seed number, fruit diameter and maturity index. The seed number varied from 0 to 11, 0–10.82, and 0–10 per fruit in 2018, 2019 and 2020, respectively. Besides, high variations were observed in the mV3 population in terms of fruit weight and rind thickness. Through investigation of three years, two clones were completely seedless and selected as promising types. Vitamin C, total phenolic content and antioxidant activity in the fruit juice of the selected types were similar control. Furthermore, ploidy levels of the selections were investigated in order to explain the cause of seedlessness. Selected types were determined as diploid with the aid of flow cytometry. The selected lines were propagated in the field to confirm their stability and new commercial field trials have been conducted to evaluate the performances of the selections on different rootstocks.

中文翻译：

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柑橘突变育种研究：伽马辐照法改良“科山”柑橘无核型

摘要 本研究报告了伽马辐射对当地甜橙品种的诱导物理突变，以开发新的无籽品种。用来自 60Co 的伽马射线辐照有种子的 'Kozan' 普通橙 (Citrus sinensis (L.) Osb.) 树的成熟秋梢。'Kozan'普通橙的60 Gy辐照剂量的存活率为65％。为了稳定突变，2016年通过重芽培育mV3植株，将mV3代植株移栽到果园。本研究连续三年记录观察结果，并评估结出足够数量果实的树木种子数、果径、成熟度等19个果实品质性状。2018 年、2019 年和 2020 年每个果实的种子数从 0 到 11、0-10.82 和 0-10 不等，分别。此外，在 mV3 种群中观察到果实重量和果皮厚度的高度变化。经过三年的考察，有两个克隆是完全无籽的，被选为有前途的品种。所选类型果汁中的维生素 C、总酚含量和抗氧化活性与对照相似。此外，研究了选择的倍性水平以解释无籽的原因。在流式细胞术的帮助下，选定的类型被确定为二倍体。所选品系在田间繁殖以确认其稳定性，并进行了新的商业田间试验以评估所选品种在不同砧木上的性能。经过三年的考察，有两个克隆是完全无籽的，被选为有前途的品种。所选类型果汁中的维生素 C、总酚含量和抗氧化活性与对照相似。此外，研究了选择的倍性水平以解释无籽的原因。在流式细胞术的帮助下，选定的类型被确定为二倍体。所选品系在田间繁殖以确认其稳定性，并进行了新的商业田间试验以评估所选品种在不同砧木上的性能。经过三年的考察，有两个克隆是完全无籽的，被选为有前途的品种。所选类型果汁中的维生素 C、总酚含量和抗氧化活性与对照相似。此外，研究了选择的倍性水平以解释无籽的原因。在流式细胞术的帮助下，选定的类型被确定为二倍体。所选品系在田间繁殖以确认其稳定性，并进行了新的商业田间试验以评估所选品种在不同砧木上的性能。研究了选择的倍性水平以解释无籽的原因。在流式细胞术的帮助下，选定的类型被确定为二倍体。所选品系在田间繁殖以确认其稳定性，并进行了新的商业田间试验以评估所选品种在不同砧木上的性能。研究了选择的倍性水平以解释无籽的原因。在流式细胞术的帮助下，选定的类型被确定为二倍体。所选品系在田间繁殖以确认其稳定性，并进行了新的商业田间试验以评估所选品种在不同砧木上的性能。