Table 3. Chloroplast feature of leaves of Arabidopsis plants grown at elevated or ambient CO₂ in different generations.

Chloroplast feature		Number of starch grains per chloroplast profile		increase	Area per starch grain (µm2)		increase
Treatment		AC	EC		AC	EC
Generation	1	1.94±1.28a	2.76±1.41b	42.3%	0.91±0.49a	1.39±0.73b	52.7%
	8	1.90±1.34a	2.73±1.38b	43.5%	0.86±0.52a	1.24±0.66b	44.2%
	15	1.99±1.41a	2.87±1.43b	44.3%	0.81±0.57a	1.29±0.72b	59.3%
	SA*	2.05±1.29a	2.83±1.38b	37.9%	0.93±0.53a	1.36±0.69	46.2%
	SE*	1.87±1.22a	2.68±1.31b	43.8%	0.84±0.51a	1.32±0.61b	57.1%
P-value		0.074–0.750	0.103–0.792	/	0.079–0.761	0.083–0.723	/
Average		1.95	2.77	42.4%	0.87	1.32	51.9%

The values given indicate means±SD from five plants. Number of starch grains per chloroplast profile was determined according to 300 chloroplasts. Area per starch grain was determined from 150 starch grains. The fully expanded rosette leaves were sampled at stage 5.0. Mean values were compared by t-test.

^*The seeds used in the reciprocal sowing experiments were from the fifteenth generation grown in ambient CO₂ (SA) and elevated CO₂ (SE).

Abbreviations: AC: Ambient CO₂; EC: Elevated CO₂.