叶面喷施铁基纳米材料对大豆生长的影响及机制研究

Mechanistic study on the effect of foliar-applied,iron-based nanomaterials on the growth of soybean

为探究叶面喷施铁基纳米材料(NMs)对作物生长的影响及其潜在机制,利用水培试验探究了两种铁基NMs(γ-Fe_(2)O_(3) NMs和Fe_(3)O_(4) NMs)和Fe-EDTA对大豆生长的影响。先通过叶面喷施不同浓度(0、1、10、50 mg·L^(-1))的铁基NMs,确定最佳施用浓度(10 mg·L^(-1)),再在最佳施用浓度下,比较两种NMs与Fe-EDTA对大豆生长和蔗糖转运的作用效果及机制。结果表明,叶面喷施不同浓度铁基NMs对大豆地上部和地下部干质量、根长、根尖数、根体积均有促进作用,且效果随着浓度的升高呈现先增加后降低的趋势。10 mg·L^(-1)为铁基NMs促进大豆生长的最佳浓度,且不同处理组的促生效果表现为γ-Fe_(2)O_(3) NMs>Fe_(3)O_(4) NMs>螯合铁肥(相同含铁量的Fe-EDTA)。铁基NMs的缓释性及高表面活性使其比Fe-EDTA具有更高的生物可利用性,γ-Fe_(2)O_(3) NMs处理的大豆根、茎、叶中铁含量是等量Fe-EDTA处理的1.29、1.09、1.24倍;10 mg·L^(-1)γ-Fe_(2)O_(3) NMs、Fe_(3)O_(4) NMs、Fe-EDTA处理下,大豆净光合速率与对照组相比分别增加了62.7%、41.5%、30.7%,铁基NMs对大豆叶片蒸腾速率、气孔导度和胞间二氧化碳浓度的促进效果也明显高于Fe-EDTA;铁基NMs通过调控蔗糖转运相关基因(GmSWEET 15、GmSUT 2)的表达量,促进光合产物向根部的运输,增加大豆根冠比,促进根部养分(S、P、Ca、Mn、Cu)吸收。研究表明,叶面喷施纳米铁肥能够促进作物生长、蔗糖转运及养分吸收,且相对于传统铁肥其促进效果更为显著(P<0.05),这为铁基纳米肥在农业生产中的应用提供了理论依据。

In order to elucidate the effect of iron-based nanomaterials(NMs)on soybean growth and its related mechanisms,different concentrations(0,1,10 mg·L^(-1),and 50 mg·L^(-1))of γ-Fe_(2)O_(3) NMs and Fe_(3)O_(4) NMs were sprayed on the leaf of soybean cultured in hydroponic conditions.During the experiments,Fe-EDTA(10 mg·L^(-1))was used as control to compare the performance and related mechanisms of the soybean growth promotion by nanofertilizer and conventional fertilizers.Foliar-applied,iron-based NMs enhanced the shoot and root biomass,root length,root tips numbers,and root bulk of soybean.The biomass increased initially and decreased afterwards with the increase in iron-based NM concentration.All the treatments at 10 mg·L^(-1)exhibited the best performance for soybean growth in the order of γ-Fe_(2)O_(3) NMs>Fe_(3)O_(4) NMs>Fe-EDTA.Iron-based NMs exhibited higher bioavailability than Fe-EDTA due to the slow-release feature and high surface activity.The iron content in soybean roots,stems,and leaves after exposure to 10 mg·L^(-1) γ-Fe_(2)O_(3) NMs was 1.29-,1.09-,and 1.24-fold of that of an equal quantity of iron in Fe-EDTA exposure.The net photosynthetic rate of soybean exposed to 10 mg·L^(-1)γ-Fe_(2)O_(3) NMs,Fe_(3)O_(4) NMs,and Fe-EDTA was increased by 62.7%,41.5%,and 30.7%,respectively,compared with the control.The transpiration rate,stomatal conductance,and intracellular CO_(2) concentration of soybean leaf exposed to iron-based NMs were all higher than in the Fe-EDTA treatment.Iron-based NMs up-regulated the sucrose transporter related genes(GmSWEET 15,GmSUT 2),increased the transport of photosynthate from leaf to root,and increased the root-shoot ratio,thereby enhancing the uptake of nutrients(S,P,Ca,Mn,and Cu).In conclusion,foliar application of iron-nanofertilizer(γ-Fe_(2)O_(3) NMs)promoted the growth and nutrient uptake of soybean over conventional iron fertilizer.The results of this study provide a foundation for the application of iron-based NMs in promoting the growth of crops.