It's work!!!!!!!!
xyplot(r~temp|rh, xlab="temperature", ylab="fluorescence induction", sub=16, jitter=.05, cex=1, pch=16, lwd=2)
mygraph <- xyplot(r~temp|rh, xlab="temperature", ylab="fluorescence induction", sub=16, jitter=.05, pch=16, lwd=2)
update(mygraph, xlab=list(label="temperature", cex=2.5),ylab=list(label="fluorescence induction", cex=2.5))
Thank you so much!!!!!!!