VII. Alps-Adria Scientific Workshop
Stara Lesna, Slovakia, 2008
YIELD AND QUALITY OF SWEET CORN (Zea mays L. var.
saccharata Korn.) CULTIVARS GROWN ON DIFFERENT SOIL
TYPES
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2
2
Dragan ŽNIDARČIČ – Dean BAN – Anita Silvana ILAK PERŠURIĆ – Milan
2
3
OPLANIĆ – Aleksandra BIZJAK KONČAR
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Department of Agronomy, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana,
Slovenia, e-mail: dragan.znidarcic@bf.uni-lj.si
Department of Economic and Rural Development, Institute of Agriculture and Tourism, Poreč, Croatia
Fran Ramovš Institute of the Slovenian Language at ZRC SAZU, Ljubljana, Slovenia
Abstract: A field experiment was conducted in order to determine the influence of contrasting soils on sweet
corn (Zea mays L. var. saccharata Korn.) agronomic characteristics, yield and soluble sugars content. A study
with sweet corn was set up during 2006 in Slovenia at two locations: in clay loam soil and in sandy loam soil.
At each location 5 cultivars (Tasty Sweet Trophy F1, Tasty Gold F1, Gold Cup F1, Sweet Nugget and
Zuckergold) were tested. The highest kernel weight cultivar was Tasty Sweet Trophy F1, regardless of the
type of the soil texture. Kernel number per unit area was closely and negatively correlated with kernel weight.
The type of soil had no significant influence on soluble sugars composition. However, when the sucrose
content was observed, there were remarkable differences between cultivars irrespective of soil type.
Keywords: sweet corn, yield, agronomic characteristics, soluble sugars, Slovenia
Introduction
Commercial sweet corn (Zea mays L. var. saccharata Korn.) cultivation areas in
Slovenia are relatively minor compared with field corn cultivation areas. Furthermore,
sweet corn is usually produced on relatively small, part-time family farms. Despite the
above-mentioned constrains, interest in sweet corn production in Slovenia has grown in
recent years. This is mainly due to the fact that today more and more farmers are
looking for a new alternative to traditional vegetable growing that is threatened by
various cultivation problems. It is known that in the last few years the cultivation of
vegetables has been affected mostly by climate change and has become dependant on
high amounts of water to ensure good yields. As sweet corn is as a relative droughttolerant crop that is adapted to a wide range of climates (Bray, 1997), the production
and cultivation of sweet corn, rather than vegetables, is the most effective strategy when
facing climate changes. However, one needs to take into account that beside climate,
soil characteristics play a very important role in crop management. Several authors over
the last few years have published information relative to optimum yield and quality
evaluations for sweet corn (Öktem et al., 2004; Kwabiah, 2004; Ramachandrappa et al.,
2005; Hadi, 2005; Bódi et al., 2006; Buzás et al., 2006). The purpose of our study was
to compare the effects of different soil type (a sandy loam and a clay loam) on sweet
corn yield, agronomic characteristics, and the composition of kernel soluble sugars.
Materials and methods
Field experiment was conducted at two Slovenian locations, representing different soil
types. Soil at location 1 – Experimental Field of the Biotechnical Faculty in Ljubljana
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DOI: 10.1556/CRC.36.2008.Suppl.1
Vol. 36, 2008, Suppl.
Cereal Research Communications
(46o 04' N, 14o 31' W, 299 m altitude) – was clay loam (medium texture). Soil at
location 2 – Commercial farm near Murska Sobota (46o 38' N, 16o 11' W, 188 m
altitude) – was sandy loam (light texture). Some soil physico-chemical properties of the
experimental fields are given in Table 1. The climate at both locations is a typical
temperate continental climate. During the growing season the mean temperature in
Ljubljana was 19.0 oC and the sum of rainfall was 480.6 mm. Equivalent data for
Murska Sobota was 17.3 oC and 407.5 mm, respectively. The preceding crop in the year
before growing sweet corn was annual ryegrass at both locations. Five shrunken (Sh2)
cultivars (Tasty Sweet Trophy F1 – Royal Sluis, Tasty Gold F1 – Saatbau Linz, Gold
Cup F1 – Semenarna Ljubljana, Sweet Nugget – Saatbau Linz and Zuckergold –
Immergrün Wiena) were used as the crop material. Corn was machine sown at 5 cm
depth on May 1st 2006. Seedling rate was set for 71,500 seeds ha-1. Each experimental
field was 1000 m2 in size and each cultivar was sown in randomized complete block
with four replications. A basal dressing of 350 kg NPK (15-15-15) ha-1 was applied at
the time of sowing. Additional fertilizer other than N was supplied uniformly across the
plot areas to correct any deficiencies indicated by soil test results. Irrigation was
supplied by a combination of furrow irrigation methods and natural rainfall, according
to evapotranspiration data. All other crop procedures were followed out as used in
commercial sweet corn production. Twenty days after seedling, data were collected for
emergence. When the kernel moisture was about 70% (Olsen et al., 1990), samples from
2 rows in the centre of each replication were harvest manually early in the morning. The
content of soluble carbohydrates was analyzed separately by high performance liquid
chromatography (HPLC). The procedure was fully described by Dolenc-Šturm et al.
(1999). The obtained results were first submitted for a variance analysis, and the
arithmetic medians were then compared by the Duncan test.
Table 1. Initial soil physico-chemical properties at 0-30 cm of two experimental locations
Soil type
Sandy loam
Clay loam
pH
(KCl)
Organic matter
(g 100 g-1)
Clay
(%)
Nitrogen
(g 100 g-1)
P2O5
(mg 100 g-1)
K2O
(mg 100 g-1)
6.3
6.8
0.62
1.04
18.62
36.72
0.12
0.16
12.8
10.6
16.2
20.6
Results and discussion
Mean squares from the analysis of variance for the soil type for the duration of maturity,
yield and related agronomic data for sweet corn are given in Table 2. Days from
planting to harvest indicated a possible inhibitory effect in clay loam (Murska Sobota).
Sandy loam (Ljubljana) advanced harvest date with an average of 5 days. A cultivar
with shorter maturity duration (Tasty Sweet Trophy F1) was the highest kernel weight
cultivar regardless the type of the soil texture. Although it is difficult to determine the
precise influence of environmental factors on maturity in the present study, climatic
factors are likely causes. For example, a comparison among locations showed that
Ljubljana had higher mean temperature (+1.7 oC). For the site with clay loam texture,
most cultivars decreased emergence to warmer sandy loam. Field emergence among the
cultivars ranged from 80.5 to 90.2 (sandy loam) and from 71.3 to 85.4 (clay loam).
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VII. Alps-Adria Scientific Workshop
Stara Lesna, Slovakia, 2008
Even though the clay soil appeared to cause reduction in emergence, the delayed
emergence had no significant influence on kernel weight. Therefore, it is important to
consider that environmental factors are unlikely to be the main cause of differences in
emergence. Some authors (Douglass et al., 1993) mentioned that poor seedling
emergence was due to the reduced starch concentration in sweet corn kernels, which
results in reduction in the energy reserves required for emergence. In cereals, final grain
yield is defined mainly by the number of harvested kernels per unit area (Fisher, 1975).
In our study the number of kernel m-2 displayed significant differences among locations
and among cultivars. The final number of kernels reduction was evident in sandy loam.
The increase of single kernel weight was in response to reduced kernel number m-2.
Kernel number m-2 was highly negatively correlated with kernel weight in sandy loam
(r2 = –0.86; P < 0.001) and in clay loam (r 2 = –0.91; P < 0.001). Kernel weight ranged
from 162.1 g (Sweet Nugget) to 286.4 g (Tasty Sweet Trophy F1) and from 234.1 (Gold
Cup F1) to 340.5 (Tasty Sweet Trophy F1) in sandy and clay loam, respectively. In light
of our results, the greater kernel weight at Ljubljana (clay loam) was explained by the
fact that under hot, midsummer conditions, clay loam soil has the advantage of holding
much more moisture.
Table 2. Yield and related agronomic data from sweet corn study grown on the different type of soil
Tasty Sweet F1
Tasty Gold F1
Gold Cup F1
Zucckergold
Sweet Nugget
Days to maturity
Sandy
Clay
108 a
115 a
110 a
117 a
115 a
118 a
111 a
116 a
115 a
119 a
Mean
112 a
Cultivar
117 a
Seeds emergence (%)
Sandy
Clay
90.2 b
84.7 b
85.4 b
85.4 b
84.5 a
76.2 a
82.6 a
71.3 a
80.5 a
82.5 b
84.6 a
80.0 b
Kernel number (m-2)
Sandy
1784 a
2346 b
2754 cb
3150 c
3426 c
Clay
1786 a
2432 b
3050 c
2656 b
2113 ab
Kernel weight (mg)
Sandy
Clay
286.4 c
340.5 c
247.2 b
284.7 b
210.6 ab 234.1 a
181.5 a
272.4 b
162.1 a
314.4 bc
2692 cb
2407 b
217.6 ab
289.2 b
Table 3. Amount of soluble sugars (%) in sweet corn kernels
Tasty Sweet F1
Tasty Gold F1
Gold Cup F1
Zucckergold
Sweet Nugget
Glucose
Sandy
Clay
1.68 ab
1.75 ab
2.12 b
2.23 b
1.15 a
1.08 a
1.02 a
0.97 a
2.37 c
2.50 c
Soluble sugars (%)
Fructose
Sucrose
Sandy
Clay
Sandy
Clay
1.12 ab
1.09 ab
3.21 b
3.07 b
1.29 ab
1.40 b
4.68 b
4.86 b
0.91 a
0.75 a
1.10 a
1.17 a
1.08 ab
1.19 ab
8.76 c
8.63 c
1.72 b
1.56 b
3.45 b
3.62 b
Mean
1.67 ab
1.23 ab
Cultivar
1.71 ab
1.20 ab
4.24 b
4.27 b
Total
Sandy
Clay
6.01 ab
5.91 ab
8.09 b
8.49 b
3.16 a
3.00 a
10.86 c
10.79 c
7.54 b
7.68 b
7.13 b
7.17 b
Soluble sugar amount and composition of sweet corn cultivars is shown in Table 3. The
quality of fresh sweet corn depends to large extent on kernel sweetness (Azanza et al.,
1994). Sucrose, glucose and fructose are the three major components that contribute to
the total soluble sugar content (Evensen and Boyer, 1986). The sugar concentration in
the different types of soil at the time of fresh-market maturity showed negligible
variation. It should be noted, however, that there was a significant difference between
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DOI: 10.1556/CRC.36.2008.Suppl.1
Vol. 36, 2008, Suppl.
Cereal Research Communications
cultivars regarding the total soluble sugar content concentration and the concentration of
each individual sugar. Overall, in both accessions higher concentration of sugars was
present in the kernels of cv. Zucckergold compared to other cultivars. The ratio of total
sugar to sucrose in the kernels examined showed that sucrose accounted for almost 60%
of the total sugar concentration. The above results are in agreement with those obtained
by Hubbard and Pharr (1990) who pointed out that increasing sugar content during
ripening is primarily a function of the accumulation of sucrose, while glucose and
fructose levels are modulated to much lesser extent. Of the three major soluble sugars
assessed in this study, only sucrose level variations correlated significantly with the
total sugar level variations. In both soil types, the slope of the relation between sucrose
and total sugars content was over 0.7 (data not shown).
Conclusions
Our research serves to indicate which cultivars of sweet corn will be most successfully
grown in the two frequently types of soil in Slovenia. A major benefit associated with
sandy loam is earlier harvest, while growing sweet corn in clay loam is ultimately
translated into higher yields. It appears, however, that there was no discernible effect of
the soil type on the rate of soluble sugars. Furthermore, the research reveals the
important role of sucrose in determining total sugar concentrations and hence quality in
sweet corn kernels. Further investigation is needed to evaluate whether the results in our
study are site specific or can be applicable to other areas.
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