RESPONSE OF SWEET CORN CULTIVATED IN EASTERN POLAND TO DIFFERENT SOWING DATES AND COVERING WITH NON-WOVEN PP. PART II. EAR QUALITY TRAITS

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1 113 R. Rosa, Agricultura 13(4) 2014, RESPONSE OF SWEET CORN CULTIVATED IN EASTERN POLAND TO DIFFERENT SOWING DATES AND COVERING WITH NON-WOVEN PP. PART II. EAR QUALITY TRAITS Robert Rosa Siedlce University of Natural Sciences and Humanities 1 Abstract. Sweet corn quality is determined by such characteristics as ear length and diameter, number of kernel rows per ear, ear fill and productivity, as well as nutrient content in kernels. These traits may be influenced by environmental conditions and cultivation methods. A field experiment was conducted in to examine the effect of different sowing dates (26 th April, 10 th and 24 th May) and covering with nonwoven PP on quality traits of sweet corn ear. The experiment was carried out in eastern Poland (52º03 N; 22º33 E). Sweet corn formed ears characterised by better biometrical parameters in the cooler and wetter years 2007 and 2008 compared with the warm and dry 2006 in which, however, corn kernels contained more ascorbic acid, total sugars and sucrose than in other study years. As corn sowing was delayed, ear diameter, kernel weight, number of kernel rows per ear and dry matter content of kernels increased gradually. Most total sugars and sucrose were determined in the kernels of corn sown on the second date. In 2006, ears with most kernels were harvested from plots sown with corn on the first date, while in the cooler and wet weather during the 2008 growing season the best ear fill was found for the second and third sowing date. Covering corn in the initial stages of crop development increased biological productivity of ears as well as the dry matter content, total sugars and sucrose in kernels. Sweet Nugget F1 and Sheba F1 produced longer ears with heavier kernels which also contained more dry matter, total sugars and sucrose than Rana F1 which, however, had most kernel rows and kernels per ear. Key words: covering, ear fulfilment, ear length and diameter, kernel weight, nutritive value, sowing date, Zea mays L. saccharata Sturt. Corresponding author Adres do korespondencji: dr inż. Robert Rosa, Department of Vegetable Crops of Siedlce University of Natural Sciences and Humanities, B. Prusa 14, Siedlce, robert.rosa@uph.edu.pl

2 114 R. Rosa INTRODUCTION Sweet corn is a new potential crop for moderate climates but requires additional agronomic improvements and development due to climatic changes [Fekonja et al. 2011, Genc et al. 2013]. These changes, in particular increasing average air temperatures and an extending growing season, make it possible to sow sweet corn earlier than recommended in many places in Central and Eastern Europe, including Poland. It is important that high yields of ears and kernels should be accompanied by the best quality possible. Sowing date of sweet corn is one of the factors which influence both the ear yield and its quality. Ear quality is determined based on characteristics such as ear length and diameter, number of kernels per ear, uniformity and nutrient contents [White 1984, Waligóra and Kruczek 2003, Kruczek and Waligóra 2010, Kwabiah 2004, Farsiani et al. 2011]. The objective of the present work was to determine the effect of different sowing dates and covering on the ear quality of sweet corn cultivated in eastern Poland. MATERIAL AND METHODS The experiment was carried out in the years at the Experimental Farm in Zawady (52º03 N; 22º33 E). It studied the effect of different sowing dates and covering with non-woven PP on ear quality traits of sweet corn cultivated in eastern Poland. The description of the study conditions and methods was presented in the first part of the work Response of sweet corn cultivated in eastern Poland to different sowing dates and covering with non-woven PP. Part I. Corn yields [Rosa 2014]. Sweet corn was harvested manually in the milk stage. Ears were harvested two or three times depending on the combination studied. The assessment of ear quality traits was conducted on 30 random samples of ears taken from every plot at the second harvest. The following characteristics of ears were determined: length and diameter of marketable ears, the average mass of kernels per 1 marketable ear, biological productivity of ear, number of kernel rows in a marketable ear, as well as ear fulfilment with kernels. Ear tip fill was assigned a value of 1 to 6, depending on the length of the unfilled kernels at the ear tip. Value 1 indicated that over 30 mm of the tip was not filled, 2 = 25 to 29 mm of the tip was not filled, 3 = 20 to 24 mm of the tip was not filled, 4 = 15 to 19 mm of the tip was not filled; 5 = 10 to 14 mm of the tip was not filled; and 6 = 9 mm or less of the tip was not filled. Biological productivity of corn (Bp) was calculated according to the following model: mc mp Bp = 100 [%] mc where: m c mass of an ear without cover leaves (g), m p mass of a core (g) [Szymanek et al. 2004]. Moreover, husked kernels were used to determine the following: dry weight by drying to the constant weight at 105 C, total sugars and sucrose by the Luff-Schoorl method, L-ascorbic acid by the Tillman s method.

3 Response... Part II. Ear quality The results of the experiment were statistically analyzed with the analysis of variance (ANOVA) following the mathematical model for the split-block-split-plot design. Significance of differences was determined by the Tukey test at the significance level of P 0.05 [Winer et al. 1991]. RESULTS AND DISCUSSION Table 1 presents the effect of the main factors and their interactions on selected quality traits of sweet corn ears. Weather conditions in the study years had a highly significant effect on the characteristics studied. Sowing date had a highly significant effect on ear diameter, kernel weight and number per ear, and number of kernel rows per ear, but it did not influence the remaining traits. The interaction between years and sowing date was significant for all the characteristics except for the number of kernel rows per ear. The effect of covering on most examined parameters was not significant, and the interaction of covering with other factors was not significant, either. Sweet corn cultivars had a highly significant effect on ear quality traits. Moreover, the interaction of the sowing date, covering and cultivar was highly significant, too. Table 1. The effect of the experimental factors and their interactions on the sweet corn traits Tabela 1. Wpływ czynników doświadczenia oraz ich interakcji na cechy kukurydzy cukrowej Factor Czynnik LE 1 DE WK BP NR EF DM AA TS SU Year Rok (Y) ** ** ** ** ** ** ** ** ** ** Sowing date Termin siewu (A) ns ni ** ** ns ni ** ns ni ** ns ni ** ** Y A ** ** ** ** ns * ** ** * * Covering Osłanianie (B) ns ni ns ni ns ni * ns ni ns ni ** ns ni ** ** Y B ns ni ns ni ns ni ns ni ns ni ns ni ns ni ** * * A B ns ni ns ni ns ni ns ni * ns ni * ns ni ns ni ns ni Y A B ns ni ns ni ns ni ns ni ** ns ni ns ni ns ni ns ni ns ni Cultivar Odmiana (C) ** ** ** ** ** ** ** ns ** ** Y C * ns ni ns ni * ns ni ns ni ns ni ns ni ns ni ns ni A C * ** ** ns ni * * * * ns ni ns ni Y A C ns ni ns ni ns ni ns ni ns ni ns ni ** ns ni ** ** B C ns ni * ns ni ns ni ns ni ns ni ns ni ns ni ** ** Y B C ns ni ns ni ns ni ns ni ns ni ns ni ns ni ** ** * A B C ** ** ** ** ** ** ** ** ** ** 1 LE length of ears długość kolb, DE diameter of ears średnica kolb, WK kernel weight per marketable ear masa ziaren w kolbie handlowej, BP biological productivity of ears wydajność biologiczna kolb, NR number of kernel rows per ear liczba rzędów ziaren w kolbie, EF fulfilment of ears zaziarnienie kolb, DM dry matter content in kernel zawartość suchej masy w ziarnie, AA ascorbic acid content in kernel zawartość kwasu askorbinowego w ziarnie, TS total sugar content in kernel zawartość cukrów ogółem w ziarnie, SU sucrose content in kernel zawartość sacharozy w ziarnie * significant at P 0.05 istotne przy P 0,05 ** significant at P 0.01 istotne przy P 0,01 ns ni non-significant nieistotne Agricultura 13(4) 2014

4 116 R. Rosa Weather conditions in the study years affected the length and diameter of sweet corn marketable ears (Table 2). In 2007 and 2008, which were cooler and wetter, plants formed longer ears with a larger diameter than in the hot and dry In their experiment carried out in , Rosa et al. [2010] harvested the smallest ears in 2006, too, whereas in 2005 and 2007, when the weather was more favourable, the ears were much larger. By contrast, Waligóra and Weber [2010] cultivated sweet corn in western Poland in and found no significant differences in the ear length. Farsiani et al. [2011] reported that ear length and diameter declined due to insufficient soil moisture. Waligóra et al. [2008] found that water shortages due to low rainfall in the initial stages of sweet corn development (April and June) reduced the ear length. Rivera-Hernandez et al. [2010] believed that an increase in the other traits causes a decrease in the ear length as a consequence of drought stress, because of a decrease in photosynthesis and total biomass accumulation in the plant. Table 2. Length and diameter of ears depending on the sowing date and covering of sweet corn (average for the examined cultivars) Tabela 2. Długość i średnica kolb w zależności od terminu siewu i osłaniania kukurydzy cukrowej (średnio dla badanych odmian) Factor Czynnik Ear length Długość kolb, cm Ear diameter Średnica kolb, cm year rok mean year rok mean Sowing date Termin siewu April 26 th 26 kwietnia 18.7a* 19.9a 19.3a 19.3A 3.8a 4.4a 4.3a 4.2A May 10 th 10 maja 18.8a 19.6a 20.7b 19.7A 3.9ab 4.4a 4.9b 4.4B May 24 th 24 maja 19.5a 19.3a 19.6a 19.5A 4.1b 4.8b 4.7b 4.5B Covering Osłanianie no covering bez osłaniania 19.2a 19.8a 19.8a 19.6A 3.9a 4.5a 4.5a 4.3A non-woven PP agrowłóknina 18.8a 19.4a 20.0a 19.4A 4.0a 4.6a 4.7a 4.4A Mean Średnia 19.0A** 19.6B 19.9B A 4.5B 4.6B 4.4 * a, b, A, B values in columns followed by the same letters do not differ significantly at P 0.05 wartości w kolumnach oznaczone tymi samymi literami nie różnią się istotnie przy P 0,05 ** A, B values in rows followed by the same letters do not differ significantly at P 0.05 wartości w wierszach oznaczone tymi samymi literami nie różnią się istotnie przy P 0,05 The effect of the sowing date on sweet corn ear length and diameter varied over the study years. In 2006 and 2007, ears from plants sown on the three dates were of a similar length. When the weather was cool in 2008, the significantly longest ears were produced by corn sown on 10 th May (the second date). In 2006, ears from the third sowing date (24 th May) had a significantly larger diameter compared with the first date (26 th April). In 2007, ear diameter for the third sowing date was significantly greater compared with the first date (26 th April). In 2007, ear diameter for the final date was significantly larger compared with the first and second date. In 2008, ears harvested from corn sown on the second and third date were significantly larger in diameter than ears of corn sown on the first date. Öktem et al. [2004] cultivated sweet corn in Turkey, where hot and dry weather conditions predominate, and found that the diameter of sweet corn ears gradually increased as the sowing date was delayed. Kwabiah [2004] reported a significant increase in ear length and an insignificant increase in diameter as sowing was delayed from 1 st to 15 th and 29 th May. In turn, Panahi et al. [2010] found no

5 Response... Part II. Ear quality effect of the delayed sowing (from 5 th to 20 th May) on ear length, while the diameter was on the decline. Farsiani et al. [2011] sowed sweet corn on four dates (from 4 th May to 3 rd July) and noticed that ears were longest and largest in diameter when corn plants had been pollinated during a period of lower air temperatures. This finding may provide an explanation to the results of the present study where the largest ears were harvested in years when lower temperatures were recorded during flowering and pollination. The weight of kernels obtained from one marketable ear averaged g (Table 3). It significantly depended on the study year, sowing date and an interaction of these factors. The heaviest kernels were harvested in 2007 when the air temperature was moderate and rainfall evenly distributed. Corn ears harvested in the hot and dry 2006 had significantly the lowest kernel weight. It was by 29 and 25%, respectively, lower than in 2007 and Waligóra and Weber [2010] found no differences in kernel number per ear in In this study kernel weight per ear of corn sown on 10th and 24 th May was significantly higher compared with sowing on 26 th April in all the study years. There was no effect of the sowing date on kernel weight in 2006, whereas in 2007 kernels were the heaviest for the third sowing date, and significantly lighter for the second date. In 2008, significantly, the heaviest kernels per ear were harvested for the second date and the lightest for the first sowing date. Table 3. Kernel weight per marketable ear and biological productivity of marketable ears depending on the sowing date and covering of sweet corn (average for the examined cultivars) Tabela 3. Masa ziaren w kolbie handlowej oraz wydajność biologiczna kolb handlowych w zależności od terminu siewu i osłaniania kukurydzy cukrowej (średnio dla badanych odmian) Factor Czynnik Kernel weight per marketable ear Masa ziaren w kolbie handlowej, g Biological productivity Wydajność biologiczna, % year rok mean year rok mean Sowing date Termin siewu April 26 th 26 kwietnia 111.3a* 142.2ab 95.6a 116.4A 64.6b 67.6b 56.6a 62.9A May 10 th 10 maja 99.2a 129.6a 166.1c 131.6B 58.1a 62.4a 66.3b 62.2A May 24 th 24 maja 98.6a 164.8b 147.1b 136.8B 54.5a 68.5b 69.9b 64.3A Covering Osłanianie no covering bez osłaniania 100.2a 141.4a 129.8a 123.8A 58.3a 64.4a 63.2a 62.0A non-woven PP agrowłóknina 105.9a 149.6a 142.7a 132.7A 59.9a 67.9a 65.3a 64.4B Mean Średnia 103.0A** 145.5C 136.3B A 66.2B 64.3B 63.2 *, ** explanations as in Table 2 objaśnienia jak w tabeli 2 The weight of kernels separated manually from the ear was used to determine biological productivity of ears (Table 3). Ears harvested in 2007 and 2008, when the weather was cooler and wetter, were significantly more productive compared with In the hot and dry 2006, most productive ears were produced by corn sown on the first date, whereas in 2007 the highest productivity was recorded for the first and third date and in 2008 for the second and third date. Öktem et al. [2004] reported that as sowing of sweet corn was delayed, the share of husks decreased while the share of kernels increased. Agricultura 13(4) 2014

6 118 R. Rosa Covering of sweet corn with non-woven PP in the initial growth stages significantly increased biological productivity of ears (by 2.5%). Weather conditions in 2007 and 2008 were favourable for increased numbers of kernel rows on ears and kernel numbers per ear compared with 2006 (Table 4). In 2007 and 2008, the number of kernel rows per ear was 14.7, and kernel number per ear, determined on a 1 to 6 scale, ranged from 5.4 to 5.7. In 2006, values for the respective numbers were 13.6 and 4.5. Farsiani et al. [2011] reported significant reduction in the number of kernel rows per ear due to water stress, which is consistent with the results of this study obtained for the year Moser et al. [2006] reported that pre-anthesis drought significantly reduced the number of kernels rows. Rivera-Hernandez et al. [2010] found differences in the number of kernel rows per ear due to varying irrigation regimes, though the parameter was not significantly affected by changes in the soil moisture. It can be concluded that the number of kernel rows per ear is rather genetically-controlled than influenced by the soil moisture status. Table 4. Number of kernel rows and ear fulfillment with kernels (on a 1 to 6 scale) depending on the sowing date and covering of sweet corn (average for the examined cultivars) Tabela 4. Liczba rzędów ziaren oraz zaziarnienie kolb (wg skali 6-stopniowej) w zależności od terminu siewu i osłaniania kukurydzy cukrowej (średnio dla badanych odmian) Factor Czynnik Number of kernel rows Liczba rzędów ziaren year rok mean Ear fulfillment Zaziarnienie kolb year rok mean Sowing date Termin siewu April 26 th 26 kwietnia 13.5a* 14.6a 14.4a 14.1A 4.6ab 5.4a 5.8a 5.2A May 10 th 10 maja 13.4a 14.6a 14.6a 14.2A 5.0b 5.3a 5.7a 5.3A May 24 th 24 maja 14.0a 15.0a 15.2a 14.7B 3.9a 5.5a 5.7a 5.0A Covering Osłanianie no covering bez osłaniania 13.6a 14.8a 14.7a 14.4A 4.5a 5.4a 5.6a 5.2A non-woven PP agrowłóknina 13.7a 14.6a 14.8a 14.4A 4.4a 5.4a 5.8a 5.2A Mean Średnia 13.6A** 14.7B 14.7B A 5.4B 5.7B 5.2 Sowing date covering termin siewu osłanianie no covering bez osłaniania 13.9a 5.3a April 26 th 26 kwietnia non-woven PP agrowłóknina 14.3b 5.2a May 10 th 10 maja May 24 th 24 maja no covering bez osłaniania 14.2a 5.3a non-woven PP agrowłóknina 14.3a 5.4a no covering bez osłaniania 14.9a 4.9a non-woven PP agrowłóknina 14.5a 5.1a *, ** explanations as in Table 2 objaśnienia jak w tabeli 2 In this study, sweet corn sown on 24 th May had significantly more kernel rows per ear compared with other sowing dates, regardless of the study year. In the hot and dry 2006, the best ear fill (5.0) was observed on plots where sowing was conducted on 10 th May, while significantly lower (3.9) for the final sowing date. White [1984] reported a decline in the number of kernels per ear as sowing of sweet corn was delayed. In their studies, Kruczek and Walilgóra [2010] found no effect of the sowing date on the kernel number per ear.

7 Response... Part II. Ear quality Covering corn sown on the first date with non-woven PP increased the number of kernel rows per plant compared with the non-covered plots. In the hot year 2006, corn sown on the third date and covered with non-woven PP formed ears with fewer kernel rows compared with the non-covered plants. The average dry matter (DM) content in sweet corn kernels amounted to 21.78% (Table 5). Significantly, the most and least DM was determined in 2008 and 2007, respectively. Precipitation in 2008 was the highest and evenly distributed when corn was in bloom, formed ears and when the ears matured. Michałojć et al. [1996] found that increased soil moisture is followed by an increased dry matter content in sweet corn kernels. In the study by Zaniewicz-Bajkowska et al. [2010], the dry matter content in kernels increased in wetter years. Moreover, regardless of the study years, the dry matter content in kernels increased as sowing of sweet corn was delayed. In 2007, corn sown on the last date had a significantly higher DM content in kernels compared with other sowing dates. In 2008, the DM content was significantly higher in kernels of corn sown in May (on both dates) than in April. Covered sweet corn had a significantly increased DM content in kernels, the response being most visible for the first and third sowing date. Table 5. The dry matter and ascorbic acid contents in sweet corn kernel depending on the sowing date and covering (average for the examined cultivars) Tabela 5. Zawartość suchej masy i kwasu askorbinowego w ziarnie kukurydzy cukrowej w zależności od terminu siewu i osłaniania kukurydzy cukrowej (średnio dla badanych odmian) Factor Czynnik Dry matter Sucha masa, % Ascorbic acid Kwas askorbinowy mg g f.m. year rok mean year rok mean Sowing date Termin siewu April 26 th 26 kwietnia 22.17a* 19.42a 19.90a 20.50A 11.97b 10.86a 11.08a 11.30A May 10 th 10 maja 21.52a 18.52a 24.86b 21.63B 11.77ab 10.78a 11.30ab 11.28A May 24 th 24 maja 21.44a 24.52b 23.71b 23.22C 11.62a 11.29b 11.38b 11.43A Covering Osłanianie no covering bez osłaniania 21.28a 19.75a 21.56a 20.87A 11.71a 10.93a 10.74a 11.12A non-woven PP agrowłóknina 22.14a 21.89a 24.08a 22.70B 11.86a 11.02a 11.77b 11.55A Mean Średnia 21.71B** 20.82A 22.82C C 10.97A 11.25B Sowing date covering termin siewu osłanianie no covering bez osłaniania 18.89a 11.29a April 26 th 26 kwietnia non-woven PP agrowłóknina 22.11b 11.32a May 10 th 10 maja May 24 th 24 maja no covering bez osłaniania 21.22a 11.16a non-woven PP agrowłóknina 22.04a 11.40a no covering bez osłaniania 22.49a 10.92a non-woven PP agrowłóknina 23.96b 11.93a *, ** explanations as in Table 2 objaśnienia jak w tabeli 2 Weather conditions in the successive study years influenced the ascorbic acid (AA) content in sweet corn kernels (Table 5). Significantly the most and least ascorbic acid was accumulated by corn in 2006 (11.79 mg g f.m.) and 2007 (10.97 mg g Agricultura 13(4) 2014

8 120 R. Rosa f.m.), respectively. In 2006, corn had significantly most ascorbic acid when sown on the first than on the third date, whereas in 2007 and 2008 the AA content was the highest in corn sown on the third date, in 2008 the accumulation being significantly higher compared with the first date. Moreover, in 2008 AA content was the highest in kernels of the cover-protected corn. The average total sugar (TS) and sucrose (SU) content in sweet corn kernels amounted to 8.27 and 6.01% f.m. (Table 6). Significantly most TS and SU were determined in 2006, which was the warmest and driest study year. The results reported here are consistent with the findings of other authors. Farsiani et al. [2011] found that, when the soil is dry, corn accumulates more sugars in kernels. Also Massaci et al. [1996] as well as Dickert and Tracy [2001] found that kernels of corn suffering from water stress contain more total sugars and sucrose. However, Ertek and Kara [2013] noticed that the sugar content in kernels decreases when soil moisture is below or above a certain level. Regardless of the study years, significantly most TS and SU were determined in the kernels of corn sown on the second date; they were significantly lower for the first sowing date. In 2006 and 2007, corn sown on the second date accumulated significantly more total sugars compared with the first date. Sucrose content of corn sown on the third date in 2006 was significantly higher than for the first date. In 2008, the highest TS and SU contents in corn kernels were found for the second date. The contents were the lowest for the first date. Orosz et al. [2008] reported lower accumulation of the total and reducing sugars when the sowing date of sweet corn was delayed. Also Farsiani et al. [2011] observed varying sucrose contents in sweet corn sown on different dates. However, it is difficult to find any patterns of corn response to delayed sowing. Covering of corn plants increased TS and SC contents in kernels regardless of the remaining factors, compared with the covered plots, the effect being particularly visible in Table 6. The total sugar and sucrose contents in sweet corn kernels depending on the sowing date and covering (average for the examined cultivars) Tabela 6. Zawartość cukrów ogółem i sacharozy w ziarnie kukurydzy cukrowej w zależności od terminu siewu i osłaniania kukurydzy cukrowej (średnio dla badanych odmian) Factor Czynnik Total sugars Cukry ogółem, % f.m. Sucrose Sacharoza, % f.m. year rok mean year rok mean Sowing date Termin siewu April 26 th 26 kwietnia 8.09a* 8.05a 7.37a 7.83A 5.85a 5.85a 5.36a 5.69A May 10 th 10 maja 8.86b 8.48b 8.70c 8.68C 6.50ab 6.13a 6.31c 6.31C May 24 th 24 maja 8.58ab 8.19ab 8.17b 8.31B 6.27b 5.92a 5.90b 6.03B Covering Osłanianie no covering bez osłaniania 8.33a 8.29a 7.65a 8.09A 6.08a 6.02a 5.54a 5.88a non-woven PP agrowłóknina 8.69a 8.19a 8.50b 8.46B 6.34a 5.91a 6.18b 6.14b Mean Średnia 8.51B** 8.24A 8.08A B 5.96A 5.86A 6.01 *, ** explanations as in Table 2 objaśnienia jak w tabeli 2

9 Response... Part II. Ear quality Sweet corn cultivars had different levels of the examined biometric ear parameters (Table 7). Regardless of the study year, sowing date and covering, Sweet Nugget F1 formed the longest ears which were also the largest in diameter. Ears of Rana F1 were the smallest, and had the lowest kernel weight and biological productivity, but the numbers of kernel rows and kernels per ear were the highest. Sheba F1 formed the most biologically productive ears. According to Fritz and Michalsky [1979], kernel weight is the most important parameter when corn is cultivated for processing but, in sweet corn for direct consumption, the number of kernels per ear and ear length are of equal importance. During the three-year study period, differences between cultivars were observed for ear length, kernel weight and biological productivity of ears. Significant differences between the studied cultivars in ear length and kernel number were found for each sowing date. Individual cultivars had different kernel weights, numbers of kernel rows and kernel numbers per ear for the first and second sowing date. Ear diameters for individual cultivars were different for the first sowing date only. Covering sweet corn influenced ear quality parameters for individual sowing dates. However, it is difficult to notice any pattern of changes in the traits resulting from an interaction of the experimental factors. According to Aziz et al. [1992] and Khan et al. [1999], ear parameters are significantly affected by sweet corn cultivars, regardless of the sowing date and agronomic practices. However, the differences are geneticallycontrolled. Sweet Nugget F1 and Sheba F1 had a higher content of DM, total sugars and sucrose compared with Rana F1 (Table 8). Significant differences between DM contents of the three cultivars were found for the sowing dates and cultivation methods (covering vs non-covering). No interaction between the sowing date and cultivar was found for TS and SU, but the differences were determined between the non-covered cultivars sown on the first and second date, and the covered cultivars on the third date. Non-covered Sheba F1 sown on the first date and the covered Sweet Nugget F1 sown on the second date accumulated more AA in kernels than Rana F1. Agricultura 13(4) 2014

10 122 R. Rosa 122 R. Rosa Table 7. Ear biometric parameters of the examined sweet corn cultivars (means for years ) Tabela 7. Parametry biometryczne kolb badanych odmian kukurydzy cukrowej (średnie z lat ) Cultivar Odmiana Sowing date Termin siewu April 26 th 26 kwietnia May 10 th 10 maja May 24 th 24 maja covering osłanianie covering osłanianie covering osłanianie mean mean B1* B2 B1 B2 B1 B2 mean Ear length Długość kolb, cm Sweet Nugget F1 20.6b 21.2b 20.9B 20.8b 20.1a 20.5B 20.5b 20.4b 20.5B 20.6C Rana F1 18.3a 17.9a 18.1A 19.2a 19.2a 19.2A 18.8a 18.9a 18.8A 18.7A Sheba F1 18.5a 19.2b 18.8A 19.7ab 18.9a 19.3A 19.8ab 18.5a 19.2A 19.1B Ear diameter Średnica kolb, cm Sweet Nugget F1 4.3c 4.4b 4.4B 4.4a 4.4a 4.4A 4.5b 4.6a 4.6A 4.4B Rana F1 3.9a 4.1a 4.0A 4.3a 4.4a 4.3A 4.3a 4.6a 4.5A 4.3A Sheba F1 4.1b 4.2a 4.1A 4.4a 4.4a 4.4A 4.6b 4.5a 4.6A 4.3A Kernel weight per marketable ear Masa ziaren w kolbie handlowej, g Sweet Nugget F b 136.7b 132.9B 132.6a 136.6a 134.6AB 135.7a 142.7a 139.2A 135.6B Rana F a 107.8a 106.2A 116.8a 124.1a 120.5A 120.5a 146.6a 133.5A 120.1A Sheba F1 99.2a 120.7ab 110.0A 136.7a 142.9a 139.8B 139.2a 136.4a 137.8A 129.2B Biological productivity of ears Wydajność biologiczna kolb, % Sweet Nugget F1 63.1a 64.3ab 63.7A 62.0a 62.0ab 62.0A 61.2a 65.3a 63.3A 63.0A Rana F1 61.5a 59.7a 60.6A 58.6a 61.0a 59.8A 60.9a 66.1a 63.5A 61.3A Sheba F1 62.8a 66.2b 64.5A 63.0a 66.9b 64.9A 64.6a 67.9a 66.2A 65.2B Number of kernel rows Liczba rzędów ziaren Sweet Nugget F1 13.0a 13.0a 13.0A 12.7a 13.0a 12.9A 13.8a 12.8a 13.3A 13.0A Rana F1 15.1b 15.9c 15.5C 15.4c 15.1b 15.3C 15.8b 15.9c 15.9C 15.5C Sheba F1 13.7a 14.1b 13.9B 14.4b 14.6b 14.5B 15.2b 14.8b 15.0B 14.5B Ear fulfillment with kernels, on a 1 to 6 scale Zaziarnienie kolb, wg skali 6-stopniowej Sweet Nugget F1 5.4ab 5.2ab 5.3B 5.1a 5.5b 5.3AB 4.8a 4.9a 4.9A 5.2B Rana F1 5.6b 5.6b 5.6B 5.5a 5.8b 5.6B 5.0a 5.3a 5.2A 5.5C Sheba F1 5.0a 4.7a 4.8A 5.2a 4.9a 5.1A 4.9a 5.1a 5.0A 5.0A * B1 no covering bez osłaniania, B2 non-woven PP agrowłóknina ** values in columns followed by the same letters do not differ significantly at P 0.05 wartości w kolumnach oznaczone tymi samymi literami nie różnią się istotnie przy P 0,05 Mean Średnia

11 Response... Part II. Ear quality Response... Part II. Ear quality Table 8. The content of selected elements of nutritive value in kernel of the examined sweet corn cultivars (means for years ) Tabela 8. Zawartość wybranych elementów wartości odżywczej w ziarnie badanych odmian kukurydzy cukrowej (średnie z lat ) Cultivar Odmiana Sowing date Termin siewu April 26 th 26 kwietnia May 10 th 10 maja May 24 th 24 maja covering osłanianie mean covering osłanianie mean covering osłanianie mean B1* B2 B1 B2 B1 B2 Dry matter Sucha masa, % Sweet Nugget F b** 23.97b 21.59B 22.57b 22.17b 22.37B 23.37b 25.66c 24.51B 22.82B Rana F a 18.39a 17.74A 18.53a 20.45a 19.49A 20.43a 22.76a 21.59A 19.61A Sheba F b 23.97b 22.16B 22.57b 23.50b 23.03B 23.66b 23.46b 23.56B 22.92B Ascorbic acid Kwas askorbinowy, mg g f.m. Sweet Nugget F ab 10.90a 11.33AB 11.27a 11.96b 11.62A 10.71a 11.80a 11.25A 11.40A Rana F a 10.98a 11.03A 11.09a 11.02a 11.06A 10.85a 12.07a 11.46A 11.18A Sheba F b 11.25a 11.65B 11.12a 11.23ab 11.17A 10.88a 11.87a 11.38A 11.40A Total sugars Cukry ogółem, % f.m. Sweet Nugget F1 7.66b 8.27a 7.96A 8.53ab 8.73a 8.63A 8.01a 9.00b 8.50A 8.36B Rana F1 7.09a 7.91a 7.50A 8.24a 8.84a 8.54A 8.01a 8.11a 8.06A 8.03A Sheba F1 8.05c 8.03a 8.04A 8.81b 8.91a 8.86A 8.42a 8.34a 8.38A 8.43B Sucrose Sacharoza, % f.m. Sweet Nugget F1 5.48b 6.09a 5.78A 6.23ab 6.35a 6.29A 5.90a 6.51b 6.20A 6.09B Rana F1 5.07a 5.77a 5.42A 5.91a 6.48a 6.20A 5.78a 5.78a 5.78A 5.80A Sheba F1 5.88c 5.84a 5.86A 6.53b 6.37a 6.45A 6.11a 6.09a 6.10A 6.14B *, ** explanations as in Table 7 objaśnienia jak w tabeli 7 Mean Średnia Agricultura 13(4) 2014 Agricultura 13(4) 2014

12 124 R. Rosa CONCLUSIONS 1. Over the study years, quality parameters were affected by weather conditions. Better biometric parameters were obtained for ears in cooler and wetter years 2007 and 2008, compared with the warm and dry 2006 in which, however, kernels contained more ascorbic acid, total sugars and sucrose. 2. Delayed sowing contributed to an increased ear diameter, kernel weight, number of kernel rows per ear, but it did not affect the ear length, biological productivity and ear fulfillment, regardless of the study year. It also increased the dry matter content, total sugars and sucrose in kernels. Sweet corn sown on the second date accumulated most sugars. 3. Sweet corn s response to delayed sowing was affected by weather conditions during the growing season. In the warm and dry 2006, ears with most kernels were harvested from plots sown on the first date; in the cooler and wetter years 2007 and 2008 the greatest numbers of kernels per ear were obtained for the second and third date. In 2006, delayed sowing did not affect the dry matter content in kernels. Ascorbic acid in 2006 was the highest in corn sown on the first date, and in 2007 and 2008 on the third and second date. Sugars were the lowest in sweet corn sown on the first date in all the study years. 4. Covering of sweet corn did not significantly influence biometric traits of ears, though it protected plants against spring frosts which may occur on the earliest sowing dates. Regardless of the study year, kernels in the covered plants had more dry matter, ascorbic acid and sugars. The effect of covering was most visible in the coldest year. 5. From the examined sweet corn cultivars, Sweet Nugget F1 formed the largest ears. Ears of Rana F1 had the greatest number of kernels and kernel rows, whereas Sheba F1 had ears which were biologically most productive. Sweet Nugget F1 and Sheba F1 had kernels with more dry matter, total sugars and sucrose than Rana F1. ACKNOWLEDGEMENT Research supported by the Ministry of Science and Higher Education of Poland as part of statutory activities of the Department of Vegetable Crops, Siedlce University of Natural Sciences and Humanities. REFERENCES Aziz A., Saleem M., Rehman H., Muhammad F., Performance of maize hybrids under irrigated conditions. Sarhad J. Agric. 8(5), Dickert T.E., Tracy W.F., Irrigation and sugar in sweet corn. Wisconsin Crop Management Conference. Available at WCMC /2001/php Ertek A., Kara., Yield and quality of sweet corn under deficit irrigation. Agric. Water Manage. 129, Farsiani A., Ghobadi M.E., Jalali-Honarmand S., The effect of water deficit and sowing date on yield components and seed sugar contents of sweet corn (Zea mays L.). African J. Agric. Res. 6 (26), Fekonja M., Bavec F., Grobelnik-Mlakar S., Turinek M., Jakop M., Bavec M., Growth performance of sweet maize under non-typical maize growing conditions. Biol. Agric. Hortic. 27,

13 Response... Part II. Ear quality Fritz D., Michalsky F., Zuckermais ein Gemusenpflanze. Mais 2, Genc L., Inalpulat M., Kizil U., Mirik M., Smith S. E. Mendes M., Determination of water stress with spectral reflectance on sweet corn (Zea mays L.) using classification tree (CT) analysis. Zemdirbyste-Agriculture 100(1), Khan M.A., Akbar S., Ahmad K., Baloch M.S., Evaluation of corn hybrids for grain yield. Pak. J. Biol. Sci. 2(2), Kruczek A., Waligóra H., Response of sugar maize (Zea mays ssp. saccharata L.) to nitrogen and phosphorus fertilization methods depending on the sowing date. Part II. Cobs qualitative trains., Agricultura 9(4), 47-54, Kwabiah A.B., Growth and yield of sweet corn (Zea mays L.) cultivars in response to planting date and plastic mulch in a short-season environment. Sci. Hortic. 102, Massacci A., Battsitelli A., Loreto F., Effect of drought stress on photosynthetic characteristics, growth and sugar accumulation on filed-growth sweet sorghum. Aust. J. Plant. Physiol. 23(3), Michałojć Z., Nurzyński J., Kossowski J.,M Wpływ nawożenia azotowo-potasowego na plonowanie i skład chemiczny kukurydzy cukrowej. Ann. Univ. Mariae Curie-Skłodowska, Sect. EEE, Horticulture IV(13), Moser S.B., Feil B., Jampatong S., Stamp P., Effect of pre-anthesis drought nitrogen fertilizer rate and variety on grain yield, yield components and harvest index of tropical maize. Agric. Water Manage. 81, Öktem A., Öktem A.G., Coşcun Y., Determination of sowing dates of sweet corn (Zea mays L. saccharata Sturt.) under Şanlıurfa conditions. Turk. J. Agric. For. 28, Orosz F., Pap Z., Slezák K., Early sweet corn production. Proc. of International Ph.D. Students Conference, 26 November, Brno, Panahi M., Naseri R., Soleimani R., Efficiency of some sweet corn hybrids at two sowing dates in central Iran. Middle-East J. Sci. Res. 6(1), Rivera-Hernandez B., Carrillo-Avila E., Obrador-Olan J.J., Juarez-Lopez J.F., Aceves-Navarro L.A., Morphological quality of sweet corn (Zea mays L.) ears as response to soil moisture tension and phosphate fertilization in Campeche, Mexico. Agric. Water Manage. 97(9), Rosa R., Response of sweet corn cultivated in eastern Poland to different sowing dates and covering with non-woven PP. Part I. Corn yields., Agricultura 13(4), , Rosa R., Zaniewicz-Bajkowska A., Kosterna E, Franczuk J., The secondary effect of sunflower (Helianthus annuus L.) catch crop in sweet corn (Zea mays L. var. saccharata) cultivation. Folia Hort. 22(2), Szymanek M., Niedziółka I., Dobrzański B., Właściwości fizyczne ziarna kukurydzy cukrowej w aspekcie jego mechanicznego odcinania. Acta Agrophys. 107(4). Waligóra H., Kruczek A., Kształtowanie się cech jakościowych kolb dwóch odmian kukurydzy cukrowej w zależności od terminu siewu. Fragm. Agron. 4(80), Waligóra H., Szulc P., Skrzypczak W., Plonowanie kukurydzy cukrowej w warunkach zróżnicowanego nawożenia azotem. J. Res. Appl. Agric. Engng 53(4), Waligóra H., Weber A., Effect of weather conditions on sugar maize yield (Zea mays ssp. saccharata Koern.)., Agricultura 9(3), 75-82, Winer B.J., Brown D.R., Michels K.M., Statistical principles in experimental design. McGraw-Hill, New York. White J.M., Effect of plant spacing and planting date on sweet corn grown on muck soil in the spring. Proc. Fla. State Hort. Soc. 97, Zaniewicz-Bajkowska A., Rosa R., Kosterna E., Franczuk J., Buraczyńska D., The effect of sunflower (Helianthus annuus L.) catch crop on content of selected components of nutritive value of sweet corn (Zea mays L. var. saccharata (Sturtev.) L.H. Bailey)., Hortorum Cultus 9(4), Agricultura 13(4) 2014

14 126 R. Rosa REAKCJA KUKURYDZY CUKROWEJ UPRAWIANEJ W WARUNKACH WSCHODNIEJ POLSKI NA ZRÓŻNICOWANY TERMIN SIEWU I OSŁANIANIE AGROWŁÓKNINĄ. CZĘŚĆ II. CECHY JAKOŚCIOWE KOLB Streszczenie. Jakość kolb kukurydzy cukrowej określają m.in. takie cechy, jak długość i średnica kolb, liczba rzędów ziaren w kolbie, stopień wypełnienia kolb, ich wydajność oraz zawartość w ziarnie składników odżywczych. Na cechy te wpływać mogą warunki środowiskowe oraz metoda uprawy. W eksperymencie przeprowadzonym w latach badano wpływ zróżnicowanego terminu siewu nasion (26 kwietnia, 10 i 24 maja) oraz osłaniania agrowłokniną na cechy jakościowe kolb kukurydzy cukrowej. Eksperyment polowy przeprowadzono w warunkach klimatycznych wschodniej Polski (52º03 N; 22º33 E). Kolby o lepszych parametrach biometrycznych zebrano w latach 2007 i 2008 niż w roku 2006, w którym okres wegetacji kukurydzy charakteryzował się wysokimi temperaturami powietrza i bardzo małą ilością opadów atmosferycznych. Natomiast ziarno kukurydzy z 2006 roku zawierało więcej kwasu askorbinowego, cukrów ogółem i sacharozy niż z pozostałych lat badań. Opóźnianie terminu siewu kukurydzy, niezależnie od roku uprawy, powodowało stopniowy wzrost średnicy kolb, masy ziaren i liczby rzędów ziaren w kolbie oraz zawartości suchej masy w ziarnach. Najwięcej cukrów ogółem i sacharozy stwierdzono w ziarnach kukurydzy z drugiego terminu siewu. W najcieplejszym i suchym sezonie wegetacyjnym 2006 roku kolby o największym udziale ziaren zebrano z kukurydzy z najwcześniejszego, w chłodnym i wilgotnym roku 2008 z drugiego i trzeciego terminu siewu. Osłanianie kukurydzy cukrowej w pierwszych fazach rozwojowych wpłynęło na wzrost wydajności biologicznej kolb oraz wzrost zawartości w ziarniakach suchej masy, cukrów ogółem i sacharozy. Odmiany Sweet Nugget F1 i Sheba F1 wykształciły kolby o większej długości i masie ziaren, które zawierały więcej suchej masy, cukrów ogółem i sacharozy niż odmiana Rana F1. Kolby o największej długości i średnicy wykształciła odmiana Sweet Nugget F1. Odmiana Rana F1 charakteryzowała się największą ilością rzędów ziaren w kolbie oraz najlepszym jej zaziarnieniem. Słowa kluczowe: długość i średnica kolb, masa ziaren, osłanianie, termin uprawy, wartość odżywcza, wydajność biologiczna, zaziarnienie kolb, Zea mays L. saccharata Sturt. Accepted for print Zaakceptowano do druku: For citation Do cytowania: Rosa R., Response of sweet corn cultivated in eastern Poland to different sowing dates and covering with non-woven PP. Part II. Ear quality characteristics. Acta Sci. Pol., Agricultura 13(4),