Effects Of Fe And Zn Fertilizer On Growth And Quality Of Alfalfa

Alfalfa（Medicago sativa）pasture plays an important role in animal production and ecological environment construction in northwest China.Fertilization is the main agronomic measure to maintain alfalfa yield.Although the effect of application single trace elements on the yield and quality of alfalfa have been systematically investigated in previous studies,interaction between different microelement fertilizer may be synergism or antagonism,and more works are need to clarify the interaction effect between different microelement fertilizer.A field experiment was conducted to determine the effect of interaction between Fe and Zn fertilizer on plant biomass,morphologic features,photosynthetic characteristics,quality and feeding value,The main results are as follows:1.The appropriate application of Fe and Zn could increase the aboveground biomass of alfalfaFe fertilize increased the aboveground biomass by 11.43%～12.89%.The aboveground biomass was increased by Zn fertilizer with 6.31%～10.77%.The aboveground biomass was the highest when Fe and Zn fertilizer were F₁（9 kg/hm²）and Z₁（15 kg/hm²）,respectively.2.The proper application of Fe and Zn could increase the stem diameter of alfalfaFe fertilizer increased stem diameter and branches per plant,while it had no effect on height when Fe fertilizer increased to F₁（9 kg/hm²）.Zn fertilizer increased branches per plant,while it had no effect on height and stem diameter when Fe fertilizer increased to Z₁（15 kg/hm²）.The stem diameter was the highest at Fe and Zn with 9 and 15 kg/hm²,while interaction between Fe and Zn had no effect on the plant height and branches per plant.3.This study presents the photosynthetic features of alfalfa plant under interaction between Fe and ZnThe appropriate combination of Fe and Zn（i.e.Fe and Zn were 9,15 kg/hm²）enables stomatal conductance and net photosynthetic rate of alfalfa to reach the peak,and enables the intercellular CO₂ concentration to reduce to the lowest.4.The suitable application of Fe and Zn could improve the quality of alfalfaAs Fe fertilizer increased to F₁（9 kg/hm²）,the crude fat content of alfalfa was the highest,and the crude fiber,neutral detergent fiber and acid detergent fiber contents were the lowest;Zn fertilizer increased to Z₁（15 kg/hm²）,the crude fat and crude protein of alfalfa were the highest,and the crude fiber,neutral detergent fiber and acid detergent fiber contents were the lowest.Suitable combination of Fe and Zn fertilizers increased leaf stem ratio of alfalfa.Crude protein,crude fat and crude ash contents were the largest at F₁Z₁（Fe were 9 kg/hm²,Zn were 15 kg/hm²）combination.5.The appropriate application of Fe and Zn can improve the relative feeding value of alfalfaThe application of Fe fertilizer and Zn fertilizer increased dry matter intake,digestible dry matter and relative feed value.The relative feeding value increased to maximum at Fe and Zn fertilizer combination（Fe and Zn was 9 and 15 kg/hm²,respectively）,suggesting that Fe and Zn combination can greatly increase the feeding value.In conclusion,the suitable combination of Fe and Zn was F₁Z₁（i.e.,Fe and Zn were 9,15 kg/hm²）,which was beneficial to the aboveground biomass,photosynthetic characteristics,quality and feed value of alfalfa,which would provide useful information for fertilization management of alfalfa pasture.