Directory UMM :Data Elmu:jurnal:S:Scientia Horticulturae:Vol82.Issue3-4.Dec1999:
Scientia Horticulturae 82 (1999) 339±348
Short communication
Predicting nitrogen, magnesium and iron nutritional
status in some perennial crops using a portable
chlorophyll meter
Mahmoud M. Shaahan*, A.A. El-Sayed, E.A.A. Abou El-Nour
Botany Department, National Research Centre, El-Tahrir St., Dokki, Cairo, Egypt
Accepted 25 March 1999
Abstract
A field study was conducted through the years 1996 and 1997 in Ismailia and Sharkia
governorates, Egypt, with the horticultural crops: mango, mandarin, guava and grapevine. The
study aimed at predicting nitrogen, magnesium and iron-status under field conditions using the
pocket apparatus Hydro N-Tester (Minolta, Japan). The data showed that the apparatus can be used
as an easy and fast tool to predict both chlorophyll and N-status in the leaves of fruit trees. The
N-Tester readings in the range of 110±610 for mango, 735±820 for mandarin, 249±332 for guava
and 285±345 for grapevine were considered to be in the range for nitrogen sufficiency at the
recommended growth stages for each crop. Lower readings were considered to be in the deficiency
range and higher ones in the excess range. The N-Tester can also be used to assess Mg-status for
some fruit trees. Measurement of Fe-status using the N-Tester chlorophyll meter under field
conditions was not possible. # 1999 Elsevier Science B.V. All rights reserved.
Keywords: Horticultural crops; N-Tester; Chlorophyll; Nitrogen; Magnesium; Iron
1. Introduction
It is well know that nutrient deficiency in most cultivated crops during the growth
season causes imbalances, leading to reduced yield. Among the essential
macronutrients, nitrogen is described as the most important element for vegetative
* Corresponding author. Tel.: +20-2-336-5223; fax: +20-2-361-0850
E-mail address: sh0207@soficom.com.eg (M.M. Shaahan)
0304-4238/99/$ ± see front matter # 1999 Elsevier Science B.V. All rights reserved.
PII: S 0 3 0 4 - 4 2 3 8 ( 9 9 ) 0 0 0 6 0 - 6
340
M.M. Shaahan et al. / Scientia Horticulturae 82 (1999) 339±348
growth, flowering and fruit bearing of fruit trees (Mengel and Kirkby, 1987). One of
the results of nitrogen deficiency is lack of chlorophyll formation and a low
chlorophyll density in plant leaves (Thomson and Weier, 1962). Low levels of
magnesium (Neals, 1956), iron (Barton, 1970), and other nutrients such as sulphur,
calcium, manganese and zinc can also affect chlorophyll formation leading to
different degrees of chlorosis (Mengel and Kirkby, 1987). Consequently, chlorophyll
density in plant leaves can theoretically be used as a tool to determine the nutritional
status for some nutrients. Chlorophyll determination in the laboratory is a destructive
measurement and requires effort, time and chemicals. The pocket apparatus Hydro
N-Tester has been designed to measure the density of the green color in the leaves
which is considered to be proportional to the chlorophyll content. SPAD chlorophyll
meters have been used to determine N-status in several crops (Takebe and
Motomatsu, 1987 with corn, Takebe and Yoneyama, 1989; Takebe et al., 1990 with
rice; Wood et al., 1992, 1994 with corn, Kantety et al., 1996 with tall fescue).
The present work aimed at investigating the possible correlations between the
N-Tester readings and the total chlorophyll, total nitrogen, total magnesium and
total iron contents in the leaves of mango, mandarin, guava and grapes in an
attempt to find out an easy and fast tool to determine the nutritional requirements
of these perennial crops under field conditions.
2. Materials and methods
The study was conducted at different locations in Ismailia and Sharkia
governorates, Egypt, during 1996 and 1997.
2.1. Crops
The crops under investigation were chosen to represent different fruit groups,
evergreen and deciduous fruits and different types, i.e. Stone fruits, Citrus trees
and Pome fruits, and they were: mango (Mangifera indica cv. Zypdya), mandarin
(Citrus reticulata cv. Clamentinier mandarina), guava (Psidium guajava) and
grapevine (Vitis vinifera cv. Thomson seedless).
2.2. The chlorophyll meter used
The apparatus is the portable Hydro N-Tester (Minolta, Japan) with a reading
checker. It is battery energized and weighed ca. 225 g. Each reading is an average
of 30 measurements.
2.3. Readings and sampling
Mango: Readings on the six-month old spring flush were taken from four locations.
M.M. Shaahan et al. / Scientia Horticulturae 82 (1999) 339±348
341
Mandarin: Readings were taken on 5±7-month-old healthy mature leaves from
the middle of non-fruiting spring extension growth.
Guava: The third fully developed pair of leaves from the tip of the fruiting
terminal shoot were measured.
Grapevine: Readings were carried out on the leaf stalk of the basal leaf
opposite to a bunch cluster.
A total of 20 readings, equivalent to 600 measurements, was carried out for
each crop. All the measured leaves were freshly picked, kept in an ice box and
transported to the laboratory for analysis of total chlorophyll, total nitrogen (N),
total magnesium (Mg) and total iron (Fe).
2.4. Determinations and measurements
2.4.1. Chlorophyll determination
Part of the sample was rinsed with distilled water and dried with clean tissue
paper. The chlorophyll content was determined according to the method of
Maclachlan and Zalik (1963). The rest of the sample was washed with tap water,
0.01 N HCI, distilled water and then oven dried at 708C and ground.
2.4.2. Nutrient determination
Nitrogen was determined in the dry plant sample using a Bauschi digestion and
N2-distillation unit. A part of the dried sample was dry digested using a Muffle
furnace at 5508C (Chapman and Pratt, 1978). Mg and Fe were determined by
Atomic absorption spectrophotometry.
2.5. Data analysis
Data were subjected to the NCSS-computer program (Hintze, 1990) to
calculate the possible correlations, r2 and regression formula. The significance
levels of Snedecor and Cochran (1967) were used as references.
3. Results
3.1. Chlorophyll content
Leaf total chlorophyll content of the fruit trees under investigation is shown in
Fig. 1. The chlorophyll contents showed good correlations with the N-Tester
readings (r 0.97, 0.97, 0.97 and 0.99 (p
Short communication
Predicting nitrogen, magnesium and iron nutritional
status in some perennial crops using a portable
chlorophyll meter
Mahmoud M. Shaahan*, A.A. El-Sayed, E.A.A. Abou El-Nour
Botany Department, National Research Centre, El-Tahrir St., Dokki, Cairo, Egypt
Accepted 25 March 1999
Abstract
A field study was conducted through the years 1996 and 1997 in Ismailia and Sharkia
governorates, Egypt, with the horticultural crops: mango, mandarin, guava and grapevine. The
study aimed at predicting nitrogen, magnesium and iron-status under field conditions using the
pocket apparatus Hydro N-Tester (Minolta, Japan). The data showed that the apparatus can be used
as an easy and fast tool to predict both chlorophyll and N-status in the leaves of fruit trees. The
N-Tester readings in the range of 110±610 for mango, 735±820 for mandarin, 249±332 for guava
and 285±345 for grapevine were considered to be in the range for nitrogen sufficiency at the
recommended growth stages for each crop. Lower readings were considered to be in the deficiency
range and higher ones in the excess range. The N-Tester can also be used to assess Mg-status for
some fruit trees. Measurement of Fe-status using the N-Tester chlorophyll meter under field
conditions was not possible. # 1999 Elsevier Science B.V. All rights reserved.
Keywords: Horticultural crops; N-Tester; Chlorophyll; Nitrogen; Magnesium; Iron
1. Introduction
It is well know that nutrient deficiency in most cultivated crops during the growth
season causes imbalances, leading to reduced yield. Among the essential
macronutrients, nitrogen is described as the most important element for vegetative
* Corresponding author. Tel.: +20-2-336-5223; fax: +20-2-361-0850
E-mail address: sh0207@soficom.com.eg (M.M. Shaahan)
0304-4238/99/$ ± see front matter # 1999 Elsevier Science B.V. All rights reserved.
PII: S 0 3 0 4 - 4 2 3 8 ( 9 9 ) 0 0 0 6 0 - 6
340
M.M. Shaahan et al. / Scientia Horticulturae 82 (1999) 339±348
growth, flowering and fruit bearing of fruit trees (Mengel and Kirkby, 1987). One of
the results of nitrogen deficiency is lack of chlorophyll formation and a low
chlorophyll density in plant leaves (Thomson and Weier, 1962). Low levels of
magnesium (Neals, 1956), iron (Barton, 1970), and other nutrients such as sulphur,
calcium, manganese and zinc can also affect chlorophyll formation leading to
different degrees of chlorosis (Mengel and Kirkby, 1987). Consequently, chlorophyll
density in plant leaves can theoretically be used as a tool to determine the nutritional
status for some nutrients. Chlorophyll determination in the laboratory is a destructive
measurement and requires effort, time and chemicals. The pocket apparatus Hydro
N-Tester has been designed to measure the density of the green color in the leaves
which is considered to be proportional to the chlorophyll content. SPAD chlorophyll
meters have been used to determine N-status in several crops (Takebe and
Motomatsu, 1987 with corn, Takebe and Yoneyama, 1989; Takebe et al., 1990 with
rice; Wood et al., 1992, 1994 with corn, Kantety et al., 1996 with tall fescue).
The present work aimed at investigating the possible correlations between the
N-Tester readings and the total chlorophyll, total nitrogen, total magnesium and
total iron contents in the leaves of mango, mandarin, guava and grapes in an
attempt to find out an easy and fast tool to determine the nutritional requirements
of these perennial crops under field conditions.
2. Materials and methods
The study was conducted at different locations in Ismailia and Sharkia
governorates, Egypt, during 1996 and 1997.
2.1. Crops
The crops under investigation were chosen to represent different fruit groups,
evergreen and deciduous fruits and different types, i.e. Stone fruits, Citrus trees
and Pome fruits, and they were: mango (Mangifera indica cv. Zypdya), mandarin
(Citrus reticulata cv. Clamentinier mandarina), guava (Psidium guajava) and
grapevine (Vitis vinifera cv. Thomson seedless).
2.2. The chlorophyll meter used
The apparatus is the portable Hydro N-Tester (Minolta, Japan) with a reading
checker. It is battery energized and weighed ca. 225 g. Each reading is an average
of 30 measurements.
2.3. Readings and sampling
Mango: Readings on the six-month old spring flush were taken from four locations.
M.M. Shaahan et al. / Scientia Horticulturae 82 (1999) 339±348
341
Mandarin: Readings were taken on 5±7-month-old healthy mature leaves from
the middle of non-fruiting spring extension growth.
Guava: The third fully developed pair of leaves from the tip of the fruiting
terminal shoot were measured.
Grapevine: Readings were carried out on the leaf stalk of the basal leaf
opposite to a bunch cluster.
A total of 20 readings, equivalent to 600 measurements, was carried out for
each crop. All the measured leaves were freshly picked, kept in an ice box and
transported to the laboratory for analysis of total chlorophyll, total nitrogen (N),
total magnesium (Mg) and total iron (Fe).
2.4. Determinations and measurements
2.4.1. Chlorophyll determination
Part of the sample was rinsed with distilled water and dried with clean tissue
paper. The chlorophyll content was determined according to the method of
Maclachlan and Zalik (1963). The rest of the sample was washed with tap water,
0.01 N HCI, distilled water and then oven dried at 708C and ground.
2.4.2. Nutrient determination
Nitrogen was determined in the dry plant sample using a Bauschi digestion and
N2-distillation unit. A part of the dried sample was dry digested using a Muffle
furnace at 5508C (Chapman and Pratt, 1978). Mg and Fe were determined by
Atomic absorption spectrophotometry.
2.5. Data analysis
Data were subjected to the NCSS-computer program (Hintze, 1990) to
calculate the possible correlations, r2 and regression formula. The significance
levels of Snedecor and Cochran (1967) were used as references.
3. Results
3.1. Chlorophyll content
Leaf total chlorophyll content of the fruit trees under investigation is shown in
Fig. 1. The chlorophyll contents showed good correlations with the N-Tester
readings (r 0.97, 0.97, 0.97 and 0.99 (p