METHODS FOR OVERCOMING SEED DORMANCY AND THE INITIAL GROWTH OF Ziziphus joazeiro Mart. IN DIFFERENT SOILS

ABSTRACT: Considering the potential and importance of biodiversity of the Caatinga biome, studies on endemic species are relevant to conservation of its natural resources. The objectives of this work was to evaluate seed viability and physical methods for overcoming seed dormancy in juazeiro (Ziziphus joazeiro Mart.) and assess the influence of different types of soil on the initial growth of juazeiro plants. The experiments were conducted in three stages. In the first stage, the viability of seeds from different lots was evaluated using the tetrazolium test. The second stage was conducted in a plant nursery, evaluating the application of physical processes (scarification with sandpaper and hammer) in overcoming seed dormancy, and the initial growth of the plants. In the third step, the chlorophyll a and b contents, gas exchange and dry matter accumulation were evaluated in young juazeiro plants in three types of soil (Oxisol, Entisol and Vertisol). The results indicate that the viability of juazeiro seeds is greatly influenced by differences between the progenitor plants and by storage conditions, which enable a longevity of two years when stored at 22°C and 16% of relative humidity. The scarification methods with sandpaper and hammer are not efficient to reduce the time and uniform seed germination. The juazeiro plants have high growth potential in different edaphic environments, adapting well to soils of different textures and chemical compositions.

摘要：鉴于卡廷加（Caatinga）生物群落的生物多样性所蕴含的潜力与重要性，针对该区域特有物种的研究对其自然资源保护具有关键意义。本研究旨在评估茹阿泽罗树（Ziziphus joazeiro Mart.）的种子活力、破除其种子休眠的物理方法，并探究不同土壤类型对茹阿泽罗实生苗初始生长的影响。本试验分为三个阶段开展：第一阶段采用四唑染色试验（tetrazolium test），对不同批次的茹阿泽罗树种子活力进行检测；第二阶段在苗圃内进行，评估砂纸擦伤与锤击破皮两种物理处理方式破除种子休眠的效果，同时观测实生苗的初始生长状况；第三阶段针对氧化土（Oxisol）、新成土（Entisol）与变性土（Vertisol）三种土壤栽培的茹阿泽罗实生苗，测定其叶绿素a、b含量、气体交换参数及干物质积累量。试验结果表明，茹阿泽罗树的种子活力显著受亲本植株差异与贮藏条件影响：在22℃、相对湿度16%的贮藏条件下，种子寿命可达两年；砂纸擦伤与锤击破皮两种物理破眠方法均无法有效缩短种子萌发时间并提升萌发整齐度；茹阿泽罗树在不同土壤环境中均具备较高生长潜力，可良好适应不同质地与化学组成的土壤。