Drought stress is a serious threat to crop production in arid and semi-arid regions of the world. The research aimed to investigate the effects of putrescine on two commercial citrus rootstocks (Carrizo citrange and Volkameriana) grown under drought stress. Putrescine at three concentrations (0, 1, and 2 mM) was foliar-sprayed on pot-grown Carrizo citrange and Volkameriana seedlings under drought stress and normal conditions. Growth properties, physiological traits, and the expression of some stress-related genes were analyzed. Root growth and shoot growth were remarkably enhanced by putrescine treatment in both groups. Application of putrescine significantly increased root fresh weight, root length, and the percentage of fine roots in the seedlings. While growth, photosynthetic traits, leaf water status, and chlorophyll content decreased by drought, they were improved by putrescine application. The application of 2 mM putrescine yielded the optimal results. Furthermore, putrescine treatment significantly reduced root diameter, but increased chlorophyll fluorescence parameters, chlorophyll content, and proline and protein contents. The analysis of gene expression showed higher expression of CsNCED3 and RD22 genes in both groups under drought stress. Furthermore, the expression of these two genes was higher in putrescine-treated seedlings grown under drought stress. On the contrary, the expression of Chlase1 gene increased under drought stress but decreased as putrescine concentration increased. The adverse effects of drought stress were mitigated following the application of putrescine in both groups.

干旱压力对世界干旱和半干旱地区的农作物生产构成严重威胁。该研究旨在调查腐胺对干旱胁迫下生长的两种商业柑桔砧木（柑桔柑桔和Volkameriana）的影响。在干旱胁迫和正常条件下，将三种浓度（0、1和2 mM）的腐胺喷在盆栽的柑桔柑桔和Volkameriana幼苗上。分析了其生长特性，生理特性以及一些与胁迫相关的基因的表达。两组腐胺处理均显着提高了根的生长和枝条的生长。腐胺的施用显着增加了幼苗的根鲜重，根长和细根的百分比。生长，光合特性，叶片水分状况 干旱导致叶绿素含量降低，腐胺施用提高了叶绿素含量。施用2 mM腐胺产生了最佳结果。此外，腐胺处理显着减小了根的直径，但增加了叶绿素荧光参数，叶绿素含量以及脯氨酸和蛋白质含量。基因表达分析显示两组在干旱胁迫下的CsNCED3和RD22基因。此外，在干旱胁迫下，经腐胺处理的幼苗中这两个基因的表达较高。相反，Chlase1基因的表达在干旱胁迫下增加，但随着腐胺浓度的增加而降低。两组均施用腐胺后，干旱胁迫的不利影响得以缓解。