Agriculture Reference
In-Depth Information
in agreement with Serio et al. (
2004
), who found an improvement of organoleptic
quality and nutraceutic properties of cherry tomatoes and also intrinsic the quality
parameters of dry matter, total soluble solids, vitamin C and α-tocopherol, and an-
tioxidative potential. According to Hasegawa et al. (
2000
) and Plaut et al. (
2004
),
an increase in the dry matter of tomato fruits occurred under high saline conditions
due to an active osmotic adjustment of plants to guarantee further water uptake.
Furthermore, the correlation network analysis showed that compared to other traits,
sugar is one of the key traits for an improvement of tomato fruit quality (Zushi and
Matsuzoe
2011
). Sato et al. (
2006
) however found an increase not only in sugar
content, but also in organic and some amino acids. The authors reported that taste
panels indicated that NaCl treatment increased sweetness, acidity, umami (i.e. the
taste of deliciousness), and overall preference. Hexose concentration of the fruit
grown on NaCl treated plants significantly increased. At the same time, chloride
ions, organic and amino acids had higher concentrations in sodium chloride treated
plants than in the control group. A review of these effects is presented in Dorais
et al. (
2001
), Gruda (
2009
) and Schnitzler and Gruda (
2002
).
Recently, consumer awareness increased concerning health promoting com-
pounds and properties that can act in an antioxidant capacity and improve nutri-
tional value in vegetables (D'Amico et al.
2003
; Dumas et al.
2003
, Gruda
2009
).
Krauss et al. (
2006
) investigated the influence of three different salt levels (EC = 3,
6.5, and 10 dS m
−1
) on tomato growth and yield. Rising EC-values of the nutrient
solution increased vitamin C, lycopene and ß-carotene (the precursor to vitamin
A) in fresh fruits by up to 35 %. Phenol concentration was tendentiously enhanced,
and the phenols' antioxidative capacity and carotenoids increased on a fresh weight
basis. Since the authors did not record any change in dry weight basis, they sug-
gested that the observed increase of lycopene was due to the concentration—caused
by reduced water flux to the fruit. However, Wu et al. (
2004
) reported an increase
of lycopene (34-85%) for five cultivars tested under high EC compared to low
EC, while the increase of total soluble solids was only 12-22 %, suggesting that
the lycopene increase might be due to a plant stress response to osmotic and/or salt
stress rather than the result of high concentration caused by reduced water content
of the fruit. These results are in concordance with the results of Fanasca et al. (
2006
)
where these authors observed an increase in lycopene concentration on both a fresh
weight and dry weight basis in tomato by raising the EC from 2.5 to 8 dS m
−1
. How-
ever other authors (Krumbein et al.
2006
; Fernández-García et al.
2004
) did not find
differences in lycopene content, when plants were grown under high EC-values.
According to Wu and Kubota (
2008a
) the reason is the time of analysis because
the physiological status is very important, in respect to parameters of product qual-
ity (Schnitzler and Gruda
2002
). According to Wu and Kubota (
2008a
), lycopene
analysis should be done throughout the fruit ripening process (from late green to the
fully ripened stage) rather than at the last stage of ripeness to better understand ly-
copene synthesis since lycopene concentration in the tomato fruit increases rapidly
during the process. Therefore, Wu and Kubota (
2008a
) carried out a study where
lycopene content was analyzed at six tomato ripeness stages and found that the
