Effects of Iron Sources and Grass Species on Correction of Iron Deficiency Chlorosis in Kiwifruit Plants
A pot experiment was conducted to investigate the effects of two iron sources(Fe-EDTA and Fe-EDDHA)and five grass species(Sorghum×Sudan grass,Festuca rubra,Vulpia myuros,Lolium pe-renne,and Vicia villosa)on the correction of iron deficiency chlorosis in tissue-cultured'Qihong'kiwifruit plants.The results showed that,compared with the control,bicarbonate-induced iron deficiency(Bic)treat-ments led to a decrease in total iron content in new leaves,an increase in active iron content in roots,and a re-duction in hydrogen ion efflux in roots.These changes were likely related to an increase in the pH and electrical conductivity,and a decrease in DTPA-Fe concentration in the rhizosphere medium caused by the Bic treat-ments.Compared with the control,the Bic treatment with Fe-EDTA resulted in lower SPAD values,reduced Fv/Fm,smaller root volume,and lower total iron content in stems,as well as decreased allocation of active iron to new leaves.Conversely,the Bic treatment with Fe-EDDHA increased total iron content in stems,promoting the accumulation of iron in the above-ground parts,which helps prevent leaf iron deficiency chlorosis.Planting Sorghum×Sudan grass or Festuca rubra in the Bic treatment with Fe-EDTA increased SPAD values but re-duced the pH and electrical conductivity in the rhizosphere medium.Additionally,planting Sorghum×Sudan grass in the Bic treatment with Fe-EDTA increased active iron content in roots and new leaves,total iron con-tent in roots,and active iron allocation to new leaves,but reduced the number of new leaves,the dry weight of new leaves and stems,and active iron allocation to old leaves.Planting Festuca rubra in the Bic treatment with Fe-EDTA increased Fv/Fm and active iron content in roots.These findings suggest that under bicarbonate-in-duced iron deficiency,the application of Fe-EDDHA or the planting of Sorghum×Sudan grass or Festuca rubra can effectively alleviate iron deficiency chlorosis in kiwifruit plants,which provides a scientific basis for en-vironmentally-friendly and efficient management of iron deficiency in kiwifruit orchards on calcareous soils.
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