Kim Misun, Park Yosup, Yun Seok Kyu, Kim Sang Suk, Joa Jaeho, Moon Young-Eel, Do Gyung-Ran
Citrus Research Institute, National Institute of Horticultural & Herbal Science, Rural Development Administration, Seogwipo-si 63607, Jeju-do, Korea.
Planning and Coordination Division, National Institute of Horticultural & Herbal Science, Rural Development Administration, Wanju-gun 55365, Jeollabuk-do, Korea.
Plants (Basel). 2022 Jul 7;11(14):1801. doi: 10.3390/plants11141801.
Sunburn causes fruit browning and other physiological symptoms, reducing fruit production and quality. Therefore, we aimed to investigate the anatomical differences and abiotic stress responses in 'Nichinan 1 gou' satsuma mandarin ( Marc.) according to the severity of sunburn damage (five grades: control, no sunburn; I to IV, increasing severity of sunburn). Additionally, the quality of sunburned and non-sunburned fruits was compared, and the sunburn-inducing temperature was estimated. Anatomical observations confirmed that with increased severity of symptoms, the damage to fruit rind surface and oil glands was increased. In the analysis of peel pigments, chlorophyll content in the rind gradually decreased compared with IV, whereas the carotenoid content gradually increased up to III. The flavonoid content in the peel and pulp was the highest in III. In the 1,1-diphenyl-2-picrylhydrazyl and 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) radical analyses, the IC50 (the concentration of compound at which the percentage of inhibition is 50%) value was the lowest in grade III in peel or IV in pulp, indicating a high free radical scavenging ability. The fruit quality analysis between sunburned and non-sunburned fruits showed differences in total soluble solid content, total acidity, firmness, coloration, and free sugar and organic acid contents, indicating a significant effect on fruit quality. In the heat tolerance tests on fruit rind in the laboratory and field, the damage was confirmed at temperatures above 47 °C.
日灼会导致果实褐变及其他生理症状，降低果实产量和品质。因此，我们旨在根据日灼伤害的严重程度（五个等级：对照，无日灼；I至IV，日灼严重程度递增），研究“日南1号”温州蜜柑（Marc.）的解剖学差异和非生物胁迫响应。此外，比较了日灼果实和未日灼果实的品质，并估算了诱导日灼的温度。解剖学观察证实，随着症状严重程度的增加，果实表皮和油胞的损伤加剧。在果皮色素分析中，与IV级相比，果皮中的叶绿素含量逐渐降低，而类胡萝卜素含量在III级之前逐渐增加。III级果皮和果肉中的黄酮含量最高。在1,1-二苯基-2-苦基肼和2,2'-联氮双（3-乙基苯并噻唑啉-6-磺酸）自由基分析中，果皮III级或果肉IV级的IC50（抑制率为50%时的化合物浓度）值最低，表明自由基清除能力较高。日灼果实和未日灼果实的果实品质分析表明，在总可溶性固形物含量、总酸度、硬度、色泽以及游离糖和有机酸含量方面存在差异，表明对日灼果实品质有显著影响。在实验室和田间对果皮进行的耐热性测试中，证实温度高于47°C时会造成损伤。
