Table 1.

Correlation coefficients for the relationships between K_leaf and A or g_s across the entire growing season for each node in every experiment

	Node	R 2
		K leaf vs A	K leaf vs g s
Field 2011	3	0.61***	0.30***
	10	0.62***	0.53***
Field 2013	3	0.23***	0.34***
	10	0.59***	0.71***
Growth chamber	5	0.51***	0.59***
	8	0.13*	n.s.

Leaf gas exchange was measured at midday, and these exact same leaves were sampled for K _leaf measurement before sunrise the next morning. Asterisks indicate the significance of the correlation (*P < 0.05, ***P < 0.0001; n.s., not significant).