1. YIELD AND QUALITY OF SWEET CORN (Zea mays L. var
YIELD AND QUALITY OF SWEET CORN (Zea mays L. var. saccharata) CULTIVARS GROWN ON DIFFERENT SOIL TYPES
Dragan ŽNIDARČIČ1 – Dean BAN2 – Anita Silvana ILAK PERŠURIĆ2 – Milan OPLANIĆ2 – Aleksandra BIZJAK KONČAR3
1Department of Agronomy, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana, Slovenia,
2Department of Economic and Rural Development, Institute of Agriculture and Tourism, Poreč, Croatia
3Fran Ramovš Institute of the Slovenian Language at ZRC SAZU, Ljubljana, 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 drought-tolerant crop that is adapted to a wide range of climates, 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.
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.
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 1. 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 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). 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.
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 weight ranged from g (Sweet Nugget) to g (Tasty Sweet Trophy F1) and from g (Gold Cup F1) to g (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.
Soluble sugar amount and composition of sweet corn cultivars is shown in Table 2. 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 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.
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 (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). The climate at both locations is a typical temperate continental climate.
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.
Table 1. Yield and related agronomic data from sweet corn
Table 2. Amount of soluble sugars (%) in sweet corn kernels
Cultivar
Days to maturity
Seeds emergence (%)
Kernel number
(m-2)
Kernel weight
(mg)
Sandy
Clay
Tasty Sweet F1
108 a
115 a
90.2 b
84.7 b
1784 a
1786 a
286.4 c
340.5 c
Tasty Gold F1
110 a
117 a
85.4 b
2346 b
2432 b
247.2 b
284.7 b
Gold Cup F1
118 a
84.5 a
76.2 a
2754 cb
3050 c
210.6 ab
234.1 a
Zucckergold
111 a
116 a
82.6 a
71.3 a
3150 c
2656 b
181.5 a
272.4 b
Sweet Nugget
119 a
80.5 a
82.5 b
3426 c
2113 ab
162.1 a
314.4 bc
Mean
112 a
84.6 a
80.0 b
2692 cb
2407 b
217.6 ab
289.2 b
Cultivar
Soluble sugars (%)
Glucose
Fructose
Sucrose
Total
Sandy
Clay
Tasty Sweet F1
1.68 ab
1.75 ab
1.12 ab
1.09 ab
3.21 b
3.07 b
6.01 ab
5.91 ab
Tasty Gold F1
2.12 b
2.23 b
1.29 ab
1.40 b
4.68 b
4.86 b
8.09 b
8.49 b
Gold Cup F1
1.15 a
1.08 a
0.91 a
0.75 a
1.10 a
1.17 a
3.16 a
3.00 a
Zucckergold
1.02 a
0.97 a
1.08 ab
1.19 ab
8.76 c
8.63 c
10.86 c
10.79 c
Sweet Nugget
2.37 c
2.50 c
1.72 b
1.56 b
3.45 b
3.62 b
7.54 b
7.68 b
Mean
1.67 ab
1.71 ab
1.23 ab
1.20 ab
4.24 b
4.27 b
7.13 b
7.17 b