Improvement of yield and quality of two Spinacia oleracea L.
varieties by using different fertilizing approaches
Received: 21 October 2016 / Revised: 15 April 2017 / Accepted: 25 May 2017 / Published online: 9 June 2017
Ó Prof. H.S. Srivastava Foundation for Science and Society 2017
Abstract The effects of different fertilizers [the control
with no fertilizer (C), inorganic fertilization (I), combined
inorganic and organic fertilizer (IOHumax1) and (IOHu-
max2)] on yield and nutrients contents of two spinach vari-
eties (‘‘Balady and Viroﬂy’’) were investigated. Signiﬁcant
effects of variety were observed on vegetative growth and
nutrients contents. While Viroﬂy had signiﬁcantly higher
leaf area (236.96 cm
), stem diameter (7.43 mm) and fresh
weight of vegetative and radical parts (15.05 and 0.96 g,
respectively), Balady had signiﬁcantly higher chlorophyll
and carotene contents (0.0023 and 0.0018 g/g fw, respec-
tively). No signiﬁcant impacts of variety on vitamin C,
nitrite, nitrate and oxalates contents were observed. IOHu-
max2 treatment (4 g/l of Humax ? 100 mg/l of NH
per plant fertigation
) enhanced stem diameter and root
growth and signiﬁcantly improved the yield by produced
plants with higher stem length, leaf number and surface area.
This treatment improved the quality of plant by increasing
vitamin C content and reducing nitrite and oxalates contents.
No signiﬁcant effects of different fertilizers were observed
content. A fairly balanced yield/NO
content can be achieved with combined inorganic and
organic fertilizer (IOHumax1) and (IOHumax2).
Keywords Spinach Á Organic Á Inorganic Á Yield Á Nitrate Á
Nitrite Á Oxalates
Spinach is classed as an edible leafy vegetable belonging to
Chenopodiaceae family. It has been naturalized in central
parts of Asia as an annual plant (rarely biennial) (Kallo and
Bergh 1993; Kawazu Okimura et al. 2003). This veg-
etable contains considerable amounts of vitamins, espe-
cially C, E, folic acid and mineral components; it is also
extremely rich in antioxidants such as beta-carotene and
lutein (Gupta and Wagle 1988; Watanabe et al. 1994).
These antioxidants have anticancer properties; moreover,
beta-carotene improves lung operation and decreases risk
of diabetes, while lutein improves vision in old ages
(Moghadam et al. 2012). Spinach leaf has 3.2% protein,
0.65% ﬁber, 0.6% fat and linolenic acid (omega-3) and
linoleic acid (omega-6) (Salunkhe and Kadam 1998).
Unfortunately, as in other leafy vegetables, spinach
shows a tendency to accumulate oxalate (Heaney et al.
1988; Bohn et al. 2004), nitrates (NO
) and nitrites
) (Takebe et al. 1995; Jaworska 2005) which differ
according to the variety (Cantliffe 1992; Stagnari et al.
2007). Such compounds are unwanted in the human diet.
Nitrogen fertilizers have been identiﬁed as the major fac-
tors that inﬂuence nitrate content in vegetables (Cantliffe
1973). Nitrate can be reduced, in the human body to nitrite
which combines with hemoglobin and oxidizes Fe
, preventing the oxygen absorption and inducing
methemoglobinemia (Stagnari et al. 2007). Moreover,
nitrate can form cancer-causing compounds (Walker 1990;
Gangolli et al. 1994). In 1997, the European Commission
deﬁned the maximum acceptable level of nitrate accumu-
lation in spinach (3000 and 2500 ppm on fresh weight basis
for crops harvested from 1 November to 31 March and
from 1 April to 31 October, respectively). Oxalic acid is an
organic acid that occurs naturally in many plants. It binds
& Safaa Najla
Department of Horticulture Science, Faculty of Agriculture,
University of Damascus, P.O. Box 30621, Damascus, Syria
Physiol Mol Biol Plants (July–September 2017) 23(3):693–702