不同生育期调亏滴灌对菘蓝光合特性及品质的影响

精准调亏灌溉是菘蓝高产高效的关键技术。为探究不同生育期膜下调亏滴灌对菘蓝光合特性、产量及品质的影响,于2015年在河西走廊中部张掖市凉州区民乐县益民灌溉试验站开展了菘蓝不同生育期、不同灌水量的试验研究。在保持其他生育期正常灌溉的情况下,在菘蓝的苗期、营养生长期、肉质根生长期和肉质根成熟期分别进行轻度和中度的水分胁迫处理,以全生育期的正常灌溉作为对照,测定菘蓝光合生理指标、产量和品质。结果表明,营养生长期和肉质根生长期水分亏缺显著降低了菘蓝叶片净光合速率、蒸腾速率和气孔导度,且随水分亏缺程度加大,降幅增大。苗期轻度干旱处理的菘蓝产量和水分利用效率最高,分别达到8 317.58 kg·hm~(-2)和2.68 kg·m~(-3);肉质根成熟期轻度干旱处理次之,而肉质根生长期中度干旱处理最低。肉质根成熟期中度干旱处理的菘蓝综合品质最优,其菘蓝靛蓝、靛玉红、(R,S)-告依春含量比生育期正常灌溉处理分别提高0.26、0.42、0.0165 mg·g-1。综合考虑产量、水分利用效率及菘蓝品质等指标,最佳菘蓝水分调控处理为肉质根成熟期轻度调亏,即肉质根成熟期土壤相对含水率为55%~80%、其余生育期土壤相对含水率为65%~100%。本研究结果为高效水管理提供了一定的理论指导。

Effect of Regulated Deficit Irrigation at Different Growth Stages on Photosynthetic Characteristicsand Fruit Quality of Isatis

Precise regulated deficit irrigation is the key technique for Isatis.The target of this study was to investigate the effects of regulated deficit irrigation at different growth stages on photosynthetic characteristics,yield andquality of Isatis,which would provide theoretical guidance for efficient water managements.The experiments of Isatis were carried out in different amounts of irrigation and growth stages in Yimin Irrigation District of Gansu Province in 2015.With other growth stage under normal water condition,the effects of irrigation schedule of Isatis were measured on photosynthetic characteristics,biological quality characteristics,and yield effect during the indigotica.Nine sets of treatments were set up on the experiment,and eight sets were mildsoil water stress and moderate soil water stress,at seedling stage,vegetative stage,fleshy rootgrowth stage and fleshy root maturity,respectively.Meanwhile,the normal water supply during the whole growth period was as the control experiment.The results showed that theleaf photosynthetic rate (Pn),transpiration rate (Tr),stomatal conductance (Gs) of Isatis were significantly reduced by water deficit regulation (WDR) in nutrition growth period and taproot growth period.The yielol and water use efficiency (WUE) of Isatis root were respective 8 317.58 kg·hm-2 and 2.68 kg·m-3,respectively,and taproot growth period by medium WDR is the lowest.The quality of Isatis root was greatly improved especially in maturity period by medium WDR.The indirubin,indigo and (R,S)-epigoitrin content of Isatis root were improved 0.26、0.42、0.0165 mg·g-1,compared to the low WDR of maturity period.Therefore,considering the yield,quality,and irrigation water use efficiency,the moderate water deficit(degree of water deficit was 55％ to 80％ at fleshy root maturity,relative soil water content of other stages maintained at 65％ to 100％)was the best irrigation frequency plan.This study provides a theoretical guidance for the efficient water management.