Chilling and forcing requirement of five international fig cultivars grown in Southeastern Brazil

ABSTRACT Chill hours availability influence break dormancy, sprouting and production of temperate fruits trees in different regions. However, there are few reports on the subject for fig tree. This study aimed to evaluate the effects of the accumulated chilling hours on the physiology and dormancy release of fig cultivars. Stem cuttings of five fig cultivars were collected at the end of winter over two crop cycles and exposed to 0, 40, 80, 120 and 160 accumulated chilling hours (CH) in a cold chamber (8±0.5 ºC). Physiology of fig buds was then evaluated with regards to antioxidant enzymes activity, carbohydrate and nitrogen contents. The exposure of fig stem cuttings with two buds to different accumulated CH presented physiological changes for antioxidant enzymes activity, carbohydrates and nitrogen contents and confirming that the cultivars responded differently to the climatic conditions of each crop cycle. Results detected that the lowest accumulated CH in field in 2018 (2.7 CH) enabled a greater effect of the artificial CH when compared to 2017 (19.5 CH). Each fig cultivar had a critical accumulation point. The cultivars Roxo de Valinhos and Pingo de Mel require less CH to break dormancy, while Troyano requires more CH to finish this vegetative rest period.

摘要：低温累积时数（Chill hours）对不同产区温带果树的休眠打破、萌芽及产量具有关键调控作用。然而，目前针对无花果的相关研究报道较为匮乏。本研究旨在探究累积低温时数对无花果品种生理特性及休眠解除的影响。本研究于两个栽培周期的冬末采集5个无花果品种的茎插条，将其置于温度为8±0.5℃的冷藏箱中，分别施加0、40、80、120及160累积低温时数（CH）处理。随后对无花果芽的生理特性进行测定，测定指标涵盖抗氧化酶活性、碳水化合物与氮含量。结果显示，携带双芽的无花果茎插条经不同累积CH处理后，其抗氧化酶活性、碳水化合物及氮含量均发生显著生理变化，同时证实不同无花果品种对各栽培周期的气候条件响应存在差异。研究发现，与2017年田间自然累积CH为19.5的情况相比，2018年田间自然累积CH仅为2.7时，人工施加的CH处理效果更为显著。每个无花果品种均存在临界累积低温时数阈值：其中Roxo de Valinhos与Pingo de Mel两个品种打破休眠所需的CH更少，而Troyano则需要更多CH才能完成其营养休眠阶段。