Osmotic conditioning and shading on the germination and on the initial growth of Myracrodruon urundeuva Allemão seedlings

The present work aimed to evaluate the osmotic conditioning and shading on the germination and on the initial growth of aroeira seedlings. The seeds were pre-imbibed in solutions with different concentrations of PEG (polyethylene glycol) and KNO3 and incubated at 10°C and 20°C temperatures, during 0 (control), 12 and 24 hours. After these periods, the seeds were dried until they reached the initial levels of humidity. After that, they were put for germinating in BOD (Biochemical Oxygen Demand) chambers, at alternated 20-30°C. The control treatment and the pre-conditionings that presented the best results in BOD germination were selected, PEG (-1.0 MPa) + KNO3 (-1.0 MPa) and KNO3 (-1.0 MPa), with pre-imbibition for 12 h and incubated in BOD at 20°C. The seeds were sowed on trays and then they were transplanted, keeping under a net covered with 50% and 70% of shading and at sunlight. The osmotic conditioning did not change the seeds germination in BOD, but the highest aerial part size was observed in PEG -1.0 MPa + KNO3-1.0 MPa treatment. The shading levels at 50% and 70% and the osmotic conditioning with PEG -1.0 MPa + KNO3-1.0 MPa offered a higher emergence in a greenhouse condition; however, at sunlight the seeds presented a better index of quality on the 145th day.

本研究旨在评估渗透引发(osmotic conditioning)与遮阴处理对阿罗伊拉(aroeira)幼苗萌发及初期生长的影响。实验所用种子经不同浓度聚乙二醇(PEG, polyethylene glycol)与硝酸钾(KNO3)溶液进行预吸胀处理，随后分别于10℃与20℃条件下孵育0小时（对照组）、12小时及24小时。处理结束后，将种子干燥至初始湿度水平。随后将种子置于生化需氧量(BOD, Biochemical Oxygen Demand)培养箱中，于20-30℃变温条件下开展萌发试验。本研究筛选出在BOD萌发试验中表现最优的预引发处理，即PEG(-1.0 MPa) + KNO3(-1.0 MPa)与KNO3(-1.0 MPa)，且该类处理的预吸胀时长为12小时、孵育温度设置为20℃。将符合该处理条件的种子播种于育苗盘后进行移栽，随后将幼苗分别置于覆盖50%、70%遮阴率的遮阳网下及全光照环境中培养。实验结果显示，渗透引发处理未改变BOD培养箱内的种子萌发率，但PEG -1.0 MPa + KNO3 -1.0 MPa处理组的地上部最大生长量更高。在温室环境下，50%、70%遮阴处理及PEG -1.0 MPa + KNO3 -1.0 MPa渗透引发处理可提升种子出苗率；而在全光照条件下，播种后第145天时种子的品质指数表现更优。