Rootstocks and planting types on root architecture and vegetative vigor of ‘Pera’ sweet orange trees

ABSTRACT Root architecture affects plant growth and agricultural productions. Although it is related to genetic factors, soil physical limitations can affect the root system and volume of explored soil, compromising plant growth and fruit production. Considering the need to mitigate these restrictions, the objective of the present study was to evaluate two planting types (planting of protected seedlings and planting of seeds in definitive place) and two scion-rootstock combinations (‘Pera’ sweet orange, CNPMF D-6 selection, combined with ‘Santa Cruz Rangpur’ lime and ‘Sunki Tropical’ mandarin rootstocks). The experiment was conducted at the Lagoa do Coco Farm, Rio Real, BA, Brazil, in a Oxisol under rainfed conditions. Biometric, physiological, and soil water content evaluations were made during the experiment. Soil mechanical resistance to root penetration and root system characteristics were also evaluated. Roots were concentrated on the soil surface layers (0-0.40 m), extending horizontally up to 1.50 m from the plant, regardless of the management practices used. The total root length in each root diameter classes studied, root length density, and total root mean diameter were higher for planting of protected seedling, resulting in greater root development. Plants from ‘Pera’ sweet orange scion grafted on ‘Santa Cruz Rangpur’ lime rootstock had earlier production and were more vigorous. Soil structure affects root growth, and the root distribution up to 0.40 m depth is correlated with plant vigor, yield, and water status under rainfed conditions.

摘要：根系构型影响植物生长与农业生产。尽管根系性状与遗传因素密切相关，但土壤物理限制会作用于根系系统与探土体积，进而抑制植物生长、降低果实产量。鉴于缓解此类限制的现实需求，本研究旨在评估两种种植方式（保护苗定植与直播定植）以及两组接穗-砧木组合：‘佩拉’甜橙（CNPMF D-6品系）分别嫁接于‘圣克鲁斯朗普尔’酸橙与‘热带Sunki’柑橘砧木。本试验于巴西巴伊亚州里奥雷亚尔市的拉戈阿杜科科农场开展，供试土壤为雨养条件下的氧化土。试验期间开展了生物性状、生理特性及土壤含水量测定，同时评估了土壤根系穿透机械阻力与根系系统特征。结果显示：无论采用何种管理措施，根系均集中分布于土壤表层（0~0.40 m），水平扩展范围可达植株周边1.50 m处。在所研究的各根径等级中，保护苗定植处理的总根长、根长密度及总根平均直径均更高，根系发育更为优良。以‘圣克鲁斯朗普尔’酸橙为砧木的‘佩拉’甜橙接穗植株，投产更早且长势更旺盛。雨养条件下，土壤结构影响根系生长，0.40 m深度内的根系分布与植株长势、产量及水分状况呈显著相关。