Degree days, phenology and fruit quality of ‘Tahiti IAC-5’ acid lime grafted onto different rootstocks in Pindorama - SP

Abstract Few rootstock varieties are used for ‘Tahiti’ acid lime; therefore, diversification is necessary and studying the phenological phases of new scion/rootstock combinations is important for orchard management strategies. The aim of this study was to evaluate the influence of different rootstocks on the sum of degree days (DD) and on the phenology of plants and also on the quality of ‘Tahiti’ acid lime fruits, in Pindorama, SP. Six branches were marked on plants grafted onto 13 citrandarins (H), ‘Rangpur’ lime (RL), ‘Flying Dragon’ trifoliate orange (FD) and ‘Sunki’ mandarin (SM). Phenological characterization (anthesis to harvest) was performed using a grading scale. DD accumulation (anthesis to harvest) was determined considering the base temperature of 13 °C. Physical (weight, height and diameter, juice yield) and chemical (acidity, total soluble solids and ratio) characteristics of fruits were also evaluated. The experimental design was in randomized blocks with three replicates and one plant per plot. The rootstocks under study influenced DD accumulation and phenology, with early (H5, H73, H121, H135, H145, H152, FD - 1,558 at 1,676 DD and 135 to 146 days) and later combinations (H10, H14, H42, H47, H70, H150, H173, RL and SM - 1,694 to 1,829 DD and 148 to 157 days) regarding fruit maturation. The harvest point of ‘Tahiti’ acid lime fruits grafted onto H145 citrandarin and FD was advanced about 20 days in relation to the standard rootstock, RL. Total soluble solids content and fruit size were influenced by rootstocks; however, all scion/rootstock combinations presented fruits with quality characteristics within commercial standards.目前用于栽培塔希提酸橙（‘Tahiti’ acid lime）的砧木品种极为有限，因此亟需开展砧木多样化研究；而探究新型接穗/砧木组合的物候期，对优化果园管理策略具有重要意义。本研究在巴西圣保罗州平多拉马（Pindorama）开展，旨在评估不同砧木对积温（degree days, DD）总和、植株物候以及塔希提酸橙果实品质的影响。本试验对嫁接于13个枳橙品系（H）、‘朗普尔’酸橙（‘Rangpur’ lime, RL）、‘飞龙’枳壳（‘Flying Dragon’ trifoliate orange, FD）与‘Sunki’橘（‘Sunki’ mandarin, SM）的植株各标记6个枝条，以分级评分体系开展从开花到采收的物候期鉴定；以13℃为基准温度，计算各组合从开花至采收的积温累加量。同时测定果实的物理性状（单果重、果高、果径及出汁率）与化学性状（可滴定酸度、可溶性固形物总量及固酸比）。本试验采用随机区组设计，设置3次生物学重复，每小区定植1株嫁接植株。结果显示，供试砧木显著影响积温累加量与物候期，按果实成熟期可分为两类：早熟组合（H5、H73、H121、H135、H145、H152、FD：积温1558~1676 DD，历时135~146天）与晚熟组合（H10、H14、H42、H47、H70、H150、H173、RL、SM：积温1694~1829 DD，历时148~157天）。与对照砧木RL相比，嫁接于H145枳橙与FD的塔希提酸橙果实采收期提前约20天。可溶性固形物含量与果实大小受砧木影响显著，但所有接穗/砧木组合的果实品质指标均符合商业采收标准。