Polyethylene glycol damages grafted citrus plants based on biometric, physiological,and biochemical responses

Abstract Drought tolerance is a major trait for the selection of citrus rootstocks in breeding programs. PEG 4000 solution at 110 g L-1 (osmotic potential of -376 kPa) was used to evaluate biometric, physiological, and biochemical responses of grafted citrus plants in pots. ‘Valencia’ sweet orange plants grafted onto ‘Rangpur’ lime (drought tolerant) rootstock showed greater plant growth compared to that on ‘Swingle’ citrumelo (drought sensitive) rootstock, regardless of PEG-induced stress; however, biological responses to PEG were similar on both rootstocks. Plant dry weight, gas exchange, and leaf and root starch concentrations were reduced by PEG. Water potential at 2:00 p.m. and Fe and Mn leaf concentrations increased with severe phytotoxic symptoms. The results corroborate the limitation of PEG for assessing drought tolerance of citrus plants at the whole plant level.

摘要 耐旱性是柑橘砧木育种项目中筛选的关键性状。本研究采用浓度为110 g·L⁻¹（渗透势为-376 kPa）的聚乙二醇4000（PEG 4000）溶液，对盆栽嫁接柑橘植株的生物计量、生理及生化响应开展了评价。结果表明，无论是否经受PEG诱导的干旱胁迫，嫁接于朗普尔酸橙（Rangpur lime，耐旱砧木）的瓦伦西亚甜橙植株，其生长量均显著高于嫁接于斯温格尔枳橙（Swingle citrumelo，干旱敏感砧木）的植株；但两种砧木下植株对PEG的生物学响应并无显著差异。PEG胁迫会降低植株干重、气体交换参数以及叶片和根系的淀粉浓度。下午2时的水势与叶片铁、锰浓度则随严重植物毒性症状的出现而升高。本研究结果证实，PEG在整株水平上评估柑橘植株耐旱性存在局限性。