Table_1_Late-Season Sweet Orange Selections Under Huanglongbing and Citrus Canker Endemic Conditions in the Brazilian Humid Subtropical Region.DOCX

The Brazilian citrus orchards are comprised by few genotypes, which increases the risk of pest and disease outbreaks. The diversification of sweet oranges (Citrus × sinensis) in orchards also generates off-season revenue and extend the fruit processing period. This study aimed to evaluate several horticultural traits of 19 late-season sweet orange selections under citrus canker and huanglongbing (HLB) endemic condition in northwestern Paraná state, Brazil, in a long-term field experiment. Tree size, yield, fruit quality for fresh fruit and industrial markets, estimates of tree density and yield, and citrus canker and huanglongbing (HLB) incidences were assessed. The experimental design was a randomized block with three replicates and five trees per unit. The orchard was drip-irrigated and arranged at tree spacing of 6.5 m × 4.5 m. All scions were graft-compatible with Rangpur lime (C. × limonia). Valencia selections had the tallest trees and largest canopies, particularly Olinda, Frost and #121 with heights and volumes greater than 4.20 m and 43 m3, respectively. Natal África do Sul and Whit’s Late Valencia trees were the most productive with cumulative yields above 640 kg per tree. Most of the selections produced fruits of excellent physicochemical quality attending the fresh fruit and industrial market requirements. All selections showed similar horticultural characteristics for the fresh market, while Natal África do Sul and Charmute de Brotas were more suitable for juice processing. Frost Valencia and Valencia Late Fla. had the highest incidence of citrus canker on fruits (>20%), whereas IPR Folha Murcha, Charmute de Brotas and some Valencia selections (Chafeei Late, Campbell 479, Campbell 294, Olinda, Mutação and Whit’s Late) exihibed low incidence (3.0–17.7%). At 9 years, Valencia Mutação trees had high HLB incidence (93%). In contrast, Natal IAC and Folha Murcha IAC showed the lowest HLB incidence (13%). Our results revealed that Natal IAC, Folha Murcha IAC, IPR Folha Murcha, Natal Murcha, Campbell 479 Valencia and Valencia Late Fla. had the best horticultural performance in addition to low HLB incidence. Together, these late-season sweet oranges are the most advantageous selections for citrus orchard diversification under citrus canker and HLB endemic conditions in humid subtropical regions.

巴西柑橘园的种植基因型较为单一，这会增加病虫害暴发的风险。在果园中多样化种植甜橙（Citrus × sinensis），不仅可创造淡季收益，还能延长果品加工周期。本研究依托巴西巴拉那州西北部柑橘溃疡病（citrus canker）与黄龙病（huanglongbing, HLB）流行区的长期田间试验，对19个晚季甜橙品系的多项园艺性状展开评估。试验采用随机区组设计，设置3次重复，每小区种植5株果树。果园采用滴灌模式，株行距配置为6.5 m × 4.5 m。所有供试接穗均与黎檬（C. × limonia）嫁接亲和。本研究测定的性状包括树体大小、产量、鲜食与工业加工用果品品质、树体密度与产量估算值，以及柑橘溃疡病和黄龙病的发病率。瓦伦西亚品系的树体最高、冠幅最大，尤以Olinda、Frost与#121品系为甚，其树高均超过4.20 m，冠积均大于43 m³。Natal África do Sul与Whit’s Late Valencia的单株累计产量最高，均突破640 kg。多数供试品系的果实理化品质优异，可满足鲜食与工业加工市场的标准要求。所有品系的鲜食园艺性状表现相近，而Natal África do Sul与Charmute de Brotas则更适配果汁加工用途。果面柑橘溃疡病发病率方面，Frost Valencia与Valencia Late Fla.最高（>20%）；而IPR Folha Murcha、Charmute de Brotas以及部分瓦伦西亚品系（包括Chafeei Late、Campbell 479、Campbell 294、Olinda、Mutação与Whit’s Late）的发病率较低（3.0%~17.7%）。定植第9年时，Valencia Mutação的黄龙病发病率高达93%；与之相对，Natal IAC与Folha Murcha IAC的发病率最低，仅为13%。本研究结果表明，Natal IAC、Folha Murcha IAC、IPR Folha Murcha、Natal Murcha、Campbell 479 Valencia与Valencia Late Fla.不仅黄龙病发病率低，还具备优异的园艺综合表现。综上，这些晚季甜橙品系是在柑橘溃疡病与黄龙病流行的湿润亚热带区域开展柑橘园多样化种植的最优选择。