5Wojcik P,Wojcik M.Response of apple trees to boron ferti-lization under conditions of low soil boron availability[J].Sci-entia Horticulturae,2008,116:58-64.
6Cakmak I,Romheld V.Boron deficiency-induced impairment of cellular functions in plants[J].Plant and Soil,1997,193:71-83.
7Brown P H,Hu H.Phloem mobility of boron is species dependent:Evidence for phloem mobility in sorbitol-rich spe-cies[J].Ann.Bot.,1996,77:497-506.