Effects of LaCl3 on the growth and photosynthetic characteristics of Fny-infected tobacco seedlings

Plant growth, gas exchange characteristics, chlorophyll fluorescence, disease index, and disease prevention efficiency of LaCl3 in tobacco (Nicotiana glutinosa) plants infected by Fny-CMV (fny stain of cucumber mosaic virus) strain were determined. Leaf area, chloro-phyll and carotenoid contents, maximum photosynthesis rate, apparent quantum yield, and carboxylation efficiency dramatically decreased after 5 weeks post inoculation. The plants infected by Fny-CMV only presented much severer symptom than those infected in the presence of appropriate concentration of LaCl3. ETR (apparent rate of photosynthetic electron transport), NPQ (nonphotochemical quenching), qP (coef-ficient of photochemical quenching), and yield (II) in infected tobacco plants obviously reduced in higher light intensity after 5 weeks post inoculation. And these fluorescence parameters in Fny-infected plants obviously reduced compared with those in the plants infected by Fny in the presence of LaCl3. Together with the growth status and disease index, it revealed that exogenously appropriate concentration of LaCl3 could significantly alleviate the damage of tobacco seedlings caused by Fny-CMV.     

La3+对小球藻异养生长及叶绿素含量的影响

０．１～１００ｍｇ·Ｌ－１Ｌａ（ＮＯ３）３均能促进小球藻的异养生长,有助于葡萄糖的利用。异养培养时间≤３６ｈ时,Ｌａ３＋显著抑制小球藻对ＮＯ－３的吸收,之后则加速ＮＯ－３的吸收。Ｌａ３＋还能提高小球藻的叶绿素ａ、叶绿素ｂ及总叶绿素含量,最大促进百分率分别为２３．４％、２７．１％及２４．７％。