Table 2

Quality index*	Production System
Quality index*	Traditional Greenhouse			Mulch Greenhouse			Open field
Lettuce zone	External	Middle	Internal	External	Middle	Internal	External	Middle	Internal
Relative Water Content (%)	84.50^Aa	85.43^Aa	85.00^Aa	82.47^Aa	84.87^Aab	86.53^Ab	75.80^Ba	76.02^Ba	78.97^Bb
Water Content (%)nsi	95.82^Aa	95.53^Aa	95.07^Aa	93.93^Ba	93.13^Ba	93.07^Ba	91.83^Ca	91.57^Ca	92.20^Ca
Free Water Content (g/g)	9.57^Aa	10.10^Aa	10.20^Aa	16.19^Ba	12.72^Ab	10.18^Ac	3.80^Ca	6.18^Bb	6.17^Bb
Bound Water Content (g/g)	3.67^Aa	5.92^Ab	7.81^Ac	4.35^Aa	6.68^Ab	12.70^Bc	12.10^Ba	12.51^Ba	11.59^Ba
Free Water/Total Water Ratio	0.73^Aa	0.63^Ab	0.57^Ab	0.79^Aa	0.66^Ab	0.44^Bc	0.24^Ba	0.33^Bb	0.35^Bb
Acid Ascorbic Content (mg/100g FT)	29.25^Aa	26.93^Aa	16.93^Ab	9.01^Ba	17.23^Bb	14.14^Ab	16.79^Ca	20.72^Bb	18.00A^Ab
Total Mesophyll Bacteria (log(CFU/g FT))	5.31^Aa	6.45^Ab	6.36^Ab	5.98^Ba	6.44^Ab	5.98^Bb	5.35^Aa	6.90^Bb	6.71^Cb
Color Index (CI)	-6.64^Aa	-6.17^Ab	-5.20^Ac	-6.66^Aa	-5.98^Ab	-3.32^Bc	-6.10^Ba	-5.58^Ab	-3.66^Bc
Chlorophyll content (mg/100gFT)	37.27^Aa	32.23^Aa	12.21^Ab	43.05Ba	34.44^Ab	9.89Ac	45.03^Ba	41.20^Ba	18.91^Bb
Overall Visual Quality Score	8.98^Aa	8.94^Aa	9.00^Aa	9.00^Aa	8.97^Aa	9.00^Aa	7.60^Ba	8.42^Bb	8.67^Bc
Enzymatic Browning in Leaves Score	1.00^Aa	1.00^Aa	1.00^Aa	1.00^Aa	1.00^Aa	1.00^Aa	2.06^Ba	1.23^Bb	1.50^Bc
Enzymatic Browning in Butt stem Score**	1.00^A			1.00^A			1.55^B

*Lsmean values are reported, different lowercase letters indicate significant difference between zones (p<0.05) and uppercase letters indicate significant differences
between production systems (p<0.05) nsi No significant interaction
** Zones were not defined for Enzymatic Browning in Butt stem Score, therefore only between production system comparisons were performed

Table 2: Quality indices distribution by both lettuce zone (external, middle and internal) and production system (open field, traditional greenhous and mulching greenhouse) at harvest.