Published online 8 January 2009
Published in Agron J 101:193-200 (2009)
DOI: 10.2134/agronj2007.0393
© 2009 American Society of Agronomy
677 S. Segoe Rd., Madison, WI 53711 USA
Impact of Planting Date and Hybrid on Early Growth of Sweet Corn
Axel Garcia y Garcia*,
Larry C. Guerra and
Gerrit Hoogenboom
Dep. of Biological and Agricultural Engineering, The Univ. of Georgia, 1109 Experiment St., Griffin, GA 30223-1797
* Corresponding author (axelg2{at}uga.edu).
 |
ABSTRACT
|
|---|
Sweet corn (Zea mays L. var. rugosa) is a warm-weather crop that is grown in most of the United States. Normally, it is planted over an extended planting window to provide a continuous supply for the fresh market. However, this planting window exposes the crop to various stresses and weather risks. The objective of this study was to determine the effect of planting date on early growth of sweet corn with different maturities for different environmental conditions in Georgia, USA. Three yellow sweet corn genotypes, including a full homozygous sugar enhanced (se), a super sweet (sh2), and a standard or normal (su), were compared in 2004, 2005, and 2006 in two locations in Georgia. The experiment consisted of one planting date in 2004, six in 2005, and four planting dates under two water regimes in 2006. Plant growth variables that were measured included leaf area index (LAI), canopy height, and aboveground biomass from emergence to the beginning of tasseling. The growth rate as a function of thermal time (TT) was used to determine the impact of planting date on growth of sweet corn. A base temperature (Tb) of 6.6°C for the three genotypes, obtained from experimental data, was used. Days to emergence varied from 4 to 12 for the warmest and coolest growing seasons, respectively. The growth of the three sweet corn genotypes showed a clear response to planting dates as LAI, canopy height, and aboveground biomass and the individual plant components, including stem, sheath, and leaves were significantly (P < 0.05) different at the beginning of tasseling. For all experiments, the longer the maturity group, the higher the total aboveground biomass. Significant differences (P < 0.05) for growth rate were found between planting dates, genotypes, plant components and their interactions. The short-season hybrid tended to have a faster overall plant growth rate of all individual plant components during the warmer seasons. In contrast, the mid- and full-season hybrids tended to have a higher growth rate during the cooler seasons. For rainfed conditions, the short-season hybrid had higher leaf and sheath growth rates than the mid- and full-season hybrids, resulting in a higher stem growth rate. These results indicate that the effect of planting date on early growth of sweet corn is of significance, as it may lead to identification of an optimum planting window for this crop.
Abbreviations: BRF, Bledsoe Research Farm • LAI, leaf area index • se, sugar enhanced • SIRP, C.M. Stripling Irrigation Research Park • sh2, super sweet • su, standard • Tb, base temperature • TT, thermal time
Received for publication December 10, 2007.
|
INTRODUCTION
|
|---|
SWEET CORN is a warm-weather crop that is grown in most of the United States. In 2004, Florida, California, New York, and Georgia were the leading fresh-market producers, contributing to 21, 19, 12, and 11% of the total production, respectively. The southeastern USA is the most important sweet corn producer for the winter season fresh market (USDA-ERS, 2005). With the advance of the season, the production moves to the northeastern states, mainly due to changes in local weather conditions. Sweet corn is planted in a wide planting date window to allow for a regular supply to the fresh market (Tracy, 2001). As a result, the crop is exposed to major weather risks, including low temperatures during early planting and drought for all planting dates. Changes in the planting date modify the radiative and thermal conditions during the growing season (Cirilo and Andrade, 1994) due to the normal variation of the weather conditions throughout the year. This ultimately impacts the time required to reach maturity due to the variation in air and soil temperatures (Kwabiah, 2004).
Local environmental factors play a large role in good crop establishment. For instance, a combination of a warm soil temperature (20–30°C), soil moisture at or above field capacity, and a soil aggregate distribution with a geometric mean diameter between 1.0 and 6.8 mm, has been reported as favorable for rapid maize emergence (Schneider and Gupta, 1985). On the other hand, a combination of a low soil temperature (<12.5°C) and high soil water content can cause poor maize stand establishment (Dwyer et al., 2000). Field studies have demonstrated that the diurnal growth rates of maize (Benoit et al., 1990; Cirilo and Andrade, 1994) and sweet corn (Williams and Lindquist, 2007) are influenced significantly by daily maximum and minimum air temperatures.
As a strategy for the crop to use the entire growing season, Lauer et al. (1999) recommend for the northern U.S. Corn Belt to plant full-season hybrids early. Such a strategy could allow for the crop to reach physiological maturity before growth stops due to frost. However, the intraseasonal weather variation could cause a delay in planting, which would reduce the number of potential growing days. Producers, therefore, might consider using short-season hybrids (Soler et al., 2007). Because of their fast leaf appearance, short-season hybrids could provide an early canopy closure and better seasonal light interception (Begna et al., 2001). Short-season hybrids might also be preferred if an early harvest is desired (Howell et al., 1998).
Studies on the effect of planting date on sweet corn growth and development, especially during its early stages, are scarce; this limitation has also been observed by Williams and Lindquist (2007). Most of the information is from studies conducted with maize (Cirilo and Andrade, 1994). Commercial sweet corn, as compared with maize, has a decreased germination, emergence, and seedling vigor due to a smaller amount of starch in its kernels (Lizaso et al., 2007). This could result in an uneven stand and ultimately reduced production. Therefore, growth and development at early growth stages could become of critical importance for final yield in sweet corn. For instance, Lorens et al. (1987), in a study conducted in Gainesville, FL, found that a severe water stress during vegetative stages significantly affected growth and yield of two maize hybrids. Most recently, Zaidi et al. (2004), for conditions of New Delhi, India, found that excess soil moisture during early stages severely affected growth of maize, which eventually resulted in poor kernel development and yield. Additionally, few studies have been conducted under subtropical conditions that compare the growth and development of sweet corn hybrids with different maturities; for example, a study conducted by Olsen et al. (1985) in Australia. The objectives of this study were, therefore, to examine the effect of planting date on early growth of sweet corn for different subtropical conditions in Georgia, and to compare the growth rate of three sweet corn genotypes that represent three different maturity groups.
|
MATERIALS AND METHODS
|
|---|
Study Sites
Four field experiments were conducted during the 2004, 2005, and 2006 growing seasons at two locations in Georgia. In 2004 and 2006, the experiments were conducted at the Bledsoe Research Farm (BRF, 33°10' N, 84°45' W, 267 m above sea level) located in Williamson, Pike County. In 2005, the experiment was conducted at the C.M. Stripling Irrigation Research Park (SIRP, 31°17' N, 84°18' W, 51 m above sea level), located in Camilla, Mitchell County. The BRF and the SIRP represent the central western and southwestern regions of Georgia, respectively. Both regions are characterized by a humid subtropical climate (Perkins et al., 1985; Perkins et al., 1986) with 30-yr (1971–2000) averages for daily maximum, minimum, and average air temperature of 23.5, 11.3, and 17.4°C at BRF, and 27, 14, and 20.5°C at SIRP, respectively (Georgia Automated Environmental Monitoring Network, 2008). The experiments were conducted in soils characterized as Cecil sandy clay loam (clayey, kaolonitic, thermic Typic Hapludults) at BRF (Perkins et al., 1985), and Lucy loamy sand (loamy, siliceous, thermic Arenic Paleudults) soil at SIRP (Perkins, 1987).
Sweet Corn Genotypes
Three yellow sweet corn genotypes that represent different maturity groups were used: (i) ‘Summer Flavor #64Y.’, a full homozygous se genotype and short-season hybrid with 64 d to maturity; (ii) ‘Summer Sweet #7210’, a sh2 genotype and midseason hybrid with 76 d to maturity; and (iii) ‘Golden Queen’, a su genotype and full-season hybrid with 88 d to maturity (Twilley Seeds, 2004).
Experimental Design and Crop Management
The first experiment (Exp2004_i) was planted on 14 July 2004 at BRF under irrigated conditions in a randomized complete block design with four replications. Each plot was eight 10-m length rows. The second experiment (Exp2005_i) conducted in 2005 at SIRP, and the third experiment (Exp2006_i) conducted in 2006 at BRF, both under irrigated conditions, consisted of six and three planting dates, respectively. The planting dates at SIRP were 2, 18, and 31 March, 14 and 28 April, and 12 May, while planting dates at BRF were 27 March, and 10 and 25 April. For both locations the experimental design was a completely randomized block in a split-plot array and four replications; each individual plot was eight 10-m length rows. Planting date was the main treatment and the sweet corn hybrids were the subtreatments. The fourth experiment (Exp2006_r) was planted on 27 March 2006 at BRF under rainfed conditions in a randomized complete block design with three replications; each individual plot had four 14.5-m length rows.
For all experiments, the crop was planted in rows that were 0.82 m apart with 0.14 m between plants and thinned at stage V3 (three leaves) for a target population of 58,000 to 60,000 plants ha–1. Experiments at BRF received 1121 kg ha–1 of NPK (7–14–21) at planting and 224 kg ha–1 of N (ammonium sulfate) in two sidedress applications, while the experiment at SIRP received 785 kg ha–1 of NPK (5–10–15) at planting and 224 kg ha–1 of N (ammonium sulfate) in two sidedress applications. Applications were pop-up applied as dribble beside rows at planting, and at V6 to V8 (6 to 8 leaves) and V12 to VT stages (12 leaves to beginning tasseling).
For the irrigated experiments, regardless of the type of hybrid, irrigation was applied as recommended by the Georgia Cooperative Extension Service (Harrison and Lee, 2007) to avoid water stress using a lateral move at SIRP and a traveler sprinkler system at BRF. For all experiments, the fertilizer rates as well as pest and disease control were based on recommendations of the Georgia Cooperative Extension Service (Harris, 2007; Buntin, 2007; Kemerait, 2007). Daily solar radiation, air temperature, and rainfall were recorded by weather stations that are part of the Georgia Automated Environmental Monitoring Network (2008), located at a distance of 200 m or less from the experimental fields at SIRP and BRF.
Plant Sampling for Growth Analysis
In all four experiments, replications were kept completely bordered on all four sides by the external rows and 1 m of row length at the beginning and end of the rows. The two middle rows for each plot were used for nondestructive measurements, such as leaf area index (LAI) and canopy height. The remainder of the rows was used for destructive samplings for growth analysis. The LAI for EXP2004_i and EXP2005_i was obtained with a LICOR 2000 Plant Canopy Analyzer (LI-COR Biosciences, 1992) and was reported as the average of three measurements for each plot. For EXP2006_i and EXP2006_r, the LAI was derived from Eq. [1] (McKee, 1964):
 | [1] |
where PD corresponds to plant density (plants ha–1) and i = 1,2,3,...,n number of leaves per plant, and L and W correspond to measured length and maximum width (m) of a leaf, obtained from one plant per replication. The average canopy height of 1-m row length per plot was recorded. For growth analysis, all plants in a 1-m row length were cut at the ground level; roots were not sampled. The plants were separated into their individual components, including leaves (L), sheaths (SH), and stem (S). Then, the samples were dried at 70°C until constant mass was obtained.
We used the thermal time (TT, degree-days) approach (Ritchie et al., 1998), as described in Eq. [2], for growth rate analysis and for comparisons between and within planting dates.
 | [2] |
where Tmax and Tmin are the daily maximum and minimum air temperatures (°C), Tb is the base temperature, j = 1,2,3,..., and k is the number of days for which the TT is determined. The Tb was derived from our experimental data using the x intercept or development rate method (Arnold, 1959).
 | [3] |
where d is the number of days from emergence to beginning tasseling, and a and b are the intercept and slope of the regression between the development rate (1/d) of sweet corn and the average air temperature (Ta) from emergence to beginning tasseling.
Statistical Analyses
All statistical analyses were performed using SAS (SAS Institute, 2003). The PROC GLM was used to perform ANOVA and LSD (P < 0.05) for each experiment. The variables analyzed included LAI, canopy height, and total aboveground biomass of the plant and its components at beginning tasseling. The time series growth data were compared within and between experiments using a three-parameter logistic equation with TT from emergence as independent variable:
 | [4] |
where N(t) (g m–2) is the fitted growth variable (L, SH, S, T), a is the upper asymptotic value that restricts the function to a level at which the growth process saturates, b is the growth rate parameter (g m–2 TT–1), and c is the value of TT when N(t) is at saturation (a). The x0 is a fixed parameter that corresponds to the time required for the plant to grow at 90% of the saturation level a (J. Davis, 2007, personal communication). Equation [4] was fitted to a time series for each replication using the PROC NLIN (SAS Institute, 2003). A pseudocoefficient of determination (
r2) was selected for evaluating the goodness of fit of the model to each replication. The b parameter obtained from Eq. [4] for each replication was then subjected to ANOVA to determine the planting date effect on the growth rate using PROC MIXED (SAS Institute, 2003).
|
RESULTS AND DISCUSSION
|
|---|
Weather Conditions
The three cropping seasons had different weather conditions. Overall, the 2004 cropping season was dry and cool. The experiment was planted late (14 July) and the crop grew under decreasing solar radiation and air temperature. Due to heavy rainfall events that occurred at the beginning of September, the total rainfall of 449 mm during the 2004 growing season was higher than those recorded during the 2006 growing seasons for the same location (Fig. 1a
). As beginning tasseling occurred at the end August, those heavy rainfall events did not affect the early growth of the crop. The average maximum and minimum air temperatures during the growing season were 28.3°C and 17.5°C (Table 1
).
View larger version (54K):
[in this window]
[in a new window]
|
Fig. 1. Weather conditions for the locations where the experiments were conducted: solar radiation and air temperature correspond to 5-d average and rainfall to 5-d cumulative. [a] Bledsoe Research Farm, Williamson, GA 2004; [b] Stripling Irrigation Research Park, Camilla, GA 2005; [c] Bledsoe Research Farm, Williamson, GA 2006.
|
|
View this table:
[in this window]
[in a new window]
|
Table 1. Average daily solar radiation (SR), maximum and minimum air temperature, and total rainfall during the 2004, 2005, and 2006 growing seasons.
|
|
Overall, the 2005 cropping season was wet and warm. For most planting dates, the initial stages of the crop occurred under increasing air temperature and increasing solar radiation. The initial conditions for the 2 and 18 March planting dates were wet and cool due to low air temperatures and heavy rain events that occurred during March (Fig. 1b). As a consequence, the emergence was delayed, resulting in shorter growing seasons. The first three growing seasons (planting dates on 2, 18, and 31 March) were wetter than the last three growing seasons (planting dates on 14 and 28 April and 12 May). The wettest growing season, with 621 mm of total rainfall, was for the 2 March planting date, whereas the driest growing season with 419 mm of total rainfall was for the 14 April planting date. The heavy rainfall events caused by hurricane Dennis during the second week of July did not affect the experiment. The coolest growing season was for the 2 March planting date, with an average maximum and minimum air temperature of 26 and 13.6°C, whereas the warmest growing season was for the 12 May planting date with an average maximum and minimum air temperature of 31.3 and 20.5°C (Table 1).
Overall, the 2006 cropping season was dry and hot. For the three planting dates of the 2006 cropping season, the initial stages of the crop occurred under a slight increase for solar radiation and air temperature. March was exceptionally warm and the beginning of April was exceptionally cool (Fig. 1c). These conditions, in addition to a delay in the irrigation scheduling, resulted in a temporarily stressed crop in the irrigated experiment (EXP2006_i) as well as in an early stressed crop for the rainfed experiment (EXP2006_r). The wettest growing season, with 201 mm of total rainfall, was for the 25 April planting date and the driest growing season, with 163 mm of total rainfall, was for the 10 April planting date. Thus, 2006 was the driest cropping season as compared with the 2004 and 2005 cropping seasons. The coolest growing season, with average maximum and minimum air temperatures of 27 and 13°C, was for the 27 March planting date and the driest growing season, with average maximum and minimum air temperatures of 29.9 and 16.4°C was for the 25 April planting date (Table 1).
Sweet Corn Base Temperature
Days from emergence to beginning tasseling ranged from 16 to 30 for short- and from 18 to 33 for mid- and full-season hybrids. The linear regressions between the crop development rate (inverse of time period from emergence to beginning tasseling) and the average air temperature from emergence to the beginning of tasseling were significantly different from zero for each genotype (P < 0.05). The Tb was 6.5 for short-, 6.8 for mid-, and 7.1°C for full-season hybrids (Fig. 2
). These results are similar to the Tb range of 5.4 and 6.4°C observed for se, sh2, and su sweet corn genotypes grown in subtropical Australia (Olsen et al., 1985) and similar values obtained by Brooking and McPherson (1989) (Tb = 6°C) and Wilson and Salinger (1994) for sweet corn in New Zealand.
View larger version (27K):
[in this window]
[in a new window]
|
Fig. 2. Relation between development rate of sweet corn (1/d) from emergence to beginning tasseling and daily average air temperature. 1/d = 0 corresponds to the base temperature (Tb). Values in parenthesis correspond to SE of estimates.
|
|
In this study, the slopes of the regressions for all three genotypes were similar to each other, suggesting that there was no difference on Tb between maturity groups. Thus, results from all genotypes were combined, and there was a unique relationship between the development rate and the average air temperature from emergence to the beginning of tasseling that was significantly different from zero (P < 0.05). As a result, a Tb of 6.6°C was also derived. Our finding is below the values of 10°C (Williams and Lindquist, 2007) and 8°C (Lizaso et al., 2007), Tb's commonly used in the United States for sweet corn related studies. Also, our Tb of 6.6°C is consistent with values of 7°C reported by Arnold (1974) for a su genotype and values of 6.3°C most recently found by Yang et al. (1995) in an evaluation of mathematical formulae to calculate Tb for sweet corn and other crops.
Emergence
For the three sweet corn hybrids, emergence was affected by the planting date. The earlier the planting date the greater the number of days from planting to emergence. The number of days to emergence was similar between genotypes within planting dates (data not shown). There was a clear effect of soil temperature (Ts) on crop emergence. At 13.4°C Ts, emergence occurred 12 d after planting, whereas at 29°C Ts emergence occurred 4 d after planting (Fig. 3
). These results are in agreement with earlier studies showing that low soil temperature at planting slowed maize emergence (Schneider and Gupta, 1985). The first two planting dates (2 and 18 March) of EXP2005_i were exposed to low soil temperature and high soil water content (Fig. 1). As a result, there was a poor initial stand. Similarly, other studies have reported that the combination of low soil temperature and high soil water content resulted in poor maize stand establishment (Dwyer et al., 2000). We found a functional relationship between the number of days to emergence and the average soil temperature at the 5-cm depth (Fig. 3). Because the experimental fields were sufficiently irrigated, this relationship could be used to predict the number of days sweet corn requires for emergence under optimum conditions of growth and development.
View larger version (8K):
[in this window]
[in a new window]
|
Fig. 3. Relation between soil temperature at a depth of 5 cm and the number of days from planting to emergence for the three sweet corn hybrids.
|
|
Growth Analysis
In EXP2004_i (planted late in 14 July 2004), the lowest LAI, canopy height, and aboveground biomass of the plant and its components at the beginning of tasseling (Table 2
) were observed for the short-season hybrid. There was also a significant difference (P < 0.05) between the hybrids for LAI, canopy height, total aboveground biomass, and the individual plant components.
View this table:
[in this window]
[in a new window]
|
Table 2. Mean of leaf area index (LAI), canopy height, and aboveground biomass at beginning tasseling for the 14 July 2004 planting date.
|
|
In EXP2005_i, LAI and canopy height were greatly reduced when planted on 2 March, especially for the short-season hybrid. LAI for the 2 March planting date was reduced by 71, 61, and 28% for the short-, mid-, and full-season hybrids, respectively, compared with the 14 April planting date, when the highest LAI was observed (Table 3
). A significant difference (P < 0.0001) was found for the individual plant components and total aboveground biomass between planting date, hybrid, and the interaction between planting date and hybrid. There was also a significant difference (P < 0.05) between planting dates for plant biomass and the individual components within hybrids. The weather conditions for the 2 and 18 March planting dates, characterized as cool and wet, with temperatures as low as –2.4°C and rainfall events as high as 90 mm in a single day, dramatically affected the initial growth of sweet corn. Total aboveground biomass, expressed in g m–2, was as low as 54.93, 166.55, and 241.63 for the short-, mid-, and full-season hybrids, respectively. Our results are in agreement with previous results from an earlier study conducted in Iowa (Loomis, 1934) with maize plants grown in containers. Loomis (1934) found that plant growth decreased rapidly as the air temperature approached 10°C. For the short-season hybrid, more growth (214.93 g m–2) was observed for 31 March planting date, whereas more growth was observed for the mid- (270.45 g m–2) and full-season (515.79 g m–2) hybrids for the 18 March planting date. These results were partially due to the excellent weather conditions observed from April onward, which included a combination of high solar radiation (average of 21 MJ m–2 d–1) and average air temperature of 30°C during the growing seasons (Table 1 and Fig. 1). These conditions are considered optimal for sweet corn (Olsen et al., 1985) and maize growth and development (Warrington and Kanematsu, 1983; Yan and Hunt, 1999).
View this table:
[in this window]
[in a new window]
|
Table 3. Mean of leaf area index (LAI), canopy height, and aboveground biomass at beginning tasseling for the three sweet corn hybrids at six planting dates in 2005.
|
|
For EXP2006_i, which was started on 27 March 2006, LAI and canopy height followed a similar tendency between planting dates and hybrids. Values of LAI were higher for the 10 April planting date than for the 27 March and 25 April planting dates. Canopy height seemed to be the most affected trait by planting date, mainly for the short- and midseason sweet corn hybrids. Significant differences (P < 0.0001) were found for the individual plant components and total aboveground biomass between planting date, hybrid, and the planting date x hybrid interactions. For the short- and midseason sweet corn hybrids, a significant difference (P < 0.05) between planting dates was found for biomass of leaves, whereas no significant differences were observed for biomass of sheath and stem. Also, a significant difference (P < 0.05) between planting dates within hybrids was found for total aboveground biomass. Similar to what was found for EXP2005_i, April was the optimum planting window to provide an early satisfactory growth of sweet corn for the 2006 growing season (Table 4
).
View this table:
[in this window]
[in a new window]
|
Table 4. Mean of leaf area index (LAI), canopy height, and aboveground biomass at beginning tasseling for three sweet corn hybrids at three planting dates in 2006.
|
|
For the EXP2006_r, planted on 27 March under rainfed conditions, there was a significant difference (P < 0.05) for LAI between the short-, mid-, and full-season sweet corn hybrids as well as for canopy height. Significant differences (P < 0.05) were observed for the individual plant components and total aboveground biomass between hybrids (Table 5
).
View this table:
[in this window]
[in a new window]
|
Table 5. Mean of leaf area index (LAI), canopy height, and aboveground biomass at beginning tasseling for three sweet corn hybrids planted on 27 March 2006 under rainfed conditions.
|
|
Effect of Planting Date on Growth Rate of Sweet Corn
Rates of most biological processes are markedly affected by temperature (Russelle et al., 1984). Thermal time is a widely used approach to describe growth as a function of time (Abrami, 1972; Lizaso et al., 2007; Soler et al., 2007; Williams and Lindquist, 2007). Thus, the thermal time approach was used as a method to eliminate the source of variation between locations and to describe the temporal variation of the sweet corn growth. The logistic model [eq. 4], a nonlinear model with a single dependent variable (L, SH, S, or T) and an independent variable (TT), was successfully fitted to the growth data (P < 0.0001).
The SAS MIXED procedure allowed for determining significant differences (P < 0.0001) for the growth rate of sweet corn between planting dates, hybrids, and plant components as well as for the interactions. The logistic equation [Eq. 4] explained as much as 99% of the variation of the growth of the plant components, providing an acceptable level of confidence for using its b or growth rate parameter in this study (Table 6
).
View this table:
[in this window]
[in a new window]
|
Table 6. Sources of variation, degrees of freedom, and probability for a greater F for growth rate of sweet corn.
|
|
The impact of early planting date on the growth rate of sweet corn was greater for the short- than for the mid- and full-season hybrids, resulting in a significant reduction of the aboveground biomass at low temperatures at the early stage of crop establishment (Tables 3 and 7
). Studies conducted in Argentina (Cirilo and Andrade, 1994) found that maize dry matter accumulated at slower rates before silking for early plantings compared to late ones. More recently, Verheul et al. (1996) demonstrated that maize growth parameters were significantly lower at mean daily air temperatures below 14°C.
View this table:
[in this window]
[in a new window]
|
Table 7. Growth rate for leaves, sheaths, stems, and total biomass for the three sweet corn hybrids at different planting dates (PDs).
|
|
For EXP2006_r grown under rainfed conditions, the short-season hybrid had higher leaf, sheath, and stem growth rates than the mid- and full-season hybrids, resulting in a higher overall crop growth rate (Table 7). This suggests that short-season hybrids could tolerate reduced soil moisture from emergence to tasseling better than mid- and full-season hybrids, similar with what has been observed for maize by Sangakkara et al. (2004).
For the three hybrids, significant differences (P < 0.05) between planting dates were found for the growth rate of the plant components. For the short-season hybrid, leaf growth did not show any specific tendency, but the sheath tended to have a higher growth rate for late planting dates, as the growing seasons changed from cool to warm. The growth rate of the stem tended to be lower for late planting dates. For the midseason hybrid, the growth rate of the plant components tended to be higher for early planting dates but lower for planting dates from the end of March. For the full-season hybrid, the planting date of 14 July provided the highest growth rate for the plant components. Leaf and sheath growth rates were reduced by planting on 12 May, the warmest growing season. Regardless of the hybrid, planting date of 12 May tended to have the lower growth rate whereas planting date of 14 July tended to have higher growth rate of the sweet corn. During the earliest planting dates, lower growth rates of the plant components were consistently observed, whereas during the latest planting dates, except for the short-season hybrid, a tendency of higher growth rates was observed (Table 7).
The short-season hybrid tended to have a higher aboveground growth rate during the warm growing seasons (April planting dates) than the mid- and full season hybrids. Conversely, the mid- and full-season hybrids tended to have higher aboveground growth rate during cool growing seasons (March planting dates) than the short-season hybrid. Thus, low growth rates were observed for the short-season hybrid during early planting dates whereas low growth rates were observed for mid- and full-season hybrids during late planting dates. Recently, a study on the influence of planting date and weed interference on sweet corn growth and development (Williams and Lindquist, 2007) also found that late planting dates for midseason sweet corn hybrids resulted in low overall growth rate but greater aboveground biomass at tasseling.
The short-season hybrids require less TT than mid- and full-season hybrids to achieve a given growth stage. Thus, during warm growing seasons a higher growth rate of the short-season hybrid is expected. The higher growth rate observed for the mid- and full-season hybrids during the cooler growing seasons may suggest, as cited by Lauer et al. (1999), that planting full-season hybrids early can result, if weather permits, in high yields as the entire growing season can be used by the crop for photoassimilates accumulation. Although the amount of accumulated aboveground biomass at beginning tasseling was higher for the mid- and full-season hybrids than for the short-season hybrid, the latter required less TT to reach beginning tasseling, resulting in a higher growth rate.
|
CONCLUSIONS
|
|---|
For the growth stages from emergence to tasseling, our experiment showed that planting date had a significant effect on growth of three sweet corn genotypes, measured as LAI, canopy height, and aboveground biomass of the plant and its components, including stem, sheath, and leaves. Based on the 10 planting dates in this experiment and regardless of genotype, Tb was 6.6°C for sweet corn. Additionally, a functional relationship between the number of days to emergence and the average air temperature from emergence to beginning tasseling was obtained.
Significant differences for growth rates were also observed among planting dates, genotypes, plant components, and their interactions. The short-season hybrid tended to have a higher overall plant growth rate as well as a higher growth rate of all individual plant components during warmer seasons. In contrast, the mid- and full-season hybrids tended to have a higher growth rate during the cool seasons. For rainfed conditions, the short-season hybrid had higher leaf and sheath growth rates than the mid- and full-season hybrids, resulting in a higher stem growth rate. These results indicate that the effect of planting date on early growth of sweet corn is of interest as it may lead to identification of an optimum planting window for this crop.
|
ACKNOWLEDGMENTS
|
|---|
This work was conducted under the auspices of the Southeast Climate Consortium (SECC; http://SEclimate.org) and supported by a partnership with the United States Department of Agriculture-Risk Management Agency (USDA-RMA), by grants from the U.S. National Oceanic and Atmospheric Administration-Climate Program Office (NOAA-CPO) and USDA Cooperative State Research, Education and Extension Services (USDA-CSREES), and by State and Federal funds allocated to Georgia Agricultural Experiment Stations Hatch project GEO01654. The authors would like to thank Jerry Davis for his assistance with the statistical analysis.
|
NOTES
|
|---|
All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher.
|
REFERENCES
|
|---|
- Abrami, G. 1972. Optimum mean temperature for a plant growth calculated by a new method of summation. Ecology 53:893–900.
- Arnold, C.Y. 1959. The development and significance of the base temperature in a linear heat unit system. Proc. Am. Soc. Hortic. Sci. 74:430–445.
- Arnold, C.Y. 1974. Predicting stages of sweet corn (Zea mays L.) development. Proc. Am. Soc. Hortic. Sci. 99:501–505.
- Begna, S.H.D., L. Smith, R.I. Hamilton, L.M. Dwyer, and D.W. Stewart. 2001. Corn genotypic variation effects on seedling emergence and leaf appearance for short-season areas. J. Agron. Crop Sci. 186:267–271.
- Benoit, G.R., A. Olness, and K. Van Sickle. 1990. Day-night temperature effects on leaf expansion and height of field-grown corn. Agron. J. 82:690–695.[Abstract/Free Full Text]
- Brooking, I.R., and H.G. McPherson. 1989. The impact of weather on the scheduling of sweet corn for processing 1. Quantifying the link between rate of development and the environment. N. Z. J. Crop Hortic. Sci. 17:19–26.
- Buntin, D. 2007. Corn disease and nematode management. p. 23–31. In R.D. Lee (ed.) A guide to corn production in Georgia. College of Agric. and Environ. Sci., Coop. Ext. Service, Crop and Soil Sci. Dep., The Univ. of Georgia, Athens.
- Cirilo, A.G., and F.H. Andrade. 1994. Sowing date and maize productivity: I. Crop growth and dry matter partitioning. Crop Sci. 34:1039–1043.
- Dwyer, L.M., B.L. Ma, R. de Jong, and M. Tollenaar. 2000. Assessing corn seedbed condition for emergence. Can. J. Soil Sci. 80:53–61.
- Georgia Automated Environmental Monitoring Network. 2008. www.georgiaweather.net Available online [modified 12 Nov. 2008; verified 20 Nov. 2008]. AEMN, Griffin, GA.
- Harris, G.H. 2007. Fertilization. p. 10–13. In R.D. Lee (ed.) A guide to corn production in Georgia. College of Agric. and Environ. Sci., Coop Ext. Service, Crop and Soil Sci. Dep., The Univ. of Georgia, Athens.
- Harrison, K., and D. Lee. 2007. Scheduling and managing corn irrigation. p. 36–39. In D. Lee (ed.) A guide to corn production in Georgia. College of Agric. and Environ. Sci., Coop Ext. Service, Crop and Soil Sci. Dep., The Univ. of Georgia, Athens.
- Howell, T.A., J.A. Tolk, A.D. Schneider, and S.R. Evett. 1998. Evapotranspiration, yield, and water use efficiency of corn hybrids differing in maturity. Agron. J. 90:3–9.[Abstract/Free Full Text]
- Kemerait, B. 2007. Corn disease and nematode management. p. 32–35. In R.D. Lee (ed.) A guide to corn production in Georgia. College of Agric. and Environ. Sci., Coop Ext. Service, Crop and Soil Sci. Dep., The Univ. of Georgia, Athens.
- Kwabiah, A.B. 2004. 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. (Amsterdam) 102:147–166.
- Lauer, J.G., P.R. Carter, T.M. Wood, G. Diezel, D.W. Wiersma, R.E. Rand, and M.J. Mlynarek. 1999. Corn hybrid response to planting date in the northern corn belt. Agron. J. 91:834–839.[Abstract/Free Full Text]
- LI-COR Biosciences. 1992. LAI-2000 Plant Canopy Analyzer, Instruction Manual. 2nd. LI–COR, Lincoln, NE.
- Lizaso, J.I., K.J. Boote, C.M. Cherr, J.M.S. Sholberg, J.J. Casanova, J. Judge, J.W. Jones, and G. Hoogenboom. 2007. Developing a sweet corn simulation model to predict fresh market yield and quality of ears. J. Am. Soc. Hortic. Sci. 132:415–422.
- Loomis, W.E. 1934. Daily growth of maize. Am. J. Bot. 21:1–6.[CrossRef][Web of Science]
- Lorens, G.F., J.M. Bennett, and L.B. Loggale. 1987. Differences in drought resistance between two corn hybrids. II. Component analysis and growth rate. Agron. J. 79:809–813.
- McKee, G.W. 1964. A coefficient for computing leaf area in hybrid corn. Agron. J. 56:240–241.[Free Full Text]
- Olsen, J.K., C.R. McMahon, and G.L. Hammer. 1985. Prediction of sweet corn phenology in subtropical environments. Agron. J. 85:410–415.
- Perkins, H.F. 1987. Characterization data for selected Georgia soils. Spec. Publ. 43. Georgia Agric. Exp. Stn., Athens.
- Perkins, H.F., J.E. Hook, and N.W. Barbour. 1986. Soil Characteristics of Selected Areas of the Coastal Plain Experiment Station and ABAC Research Farms. Res. Bull. 346. Georgia Agric. Exp. Stn., The Univ. of Georgia, Athens.
- Perkins, H.F., L.M. Schuman, F.C. Boswell, and V. Owen. 1985. Soil Characteristics of the Bledsoe and Beckham Research Farms of the Georgia Station (Griffin). Res. Bull. 332. Georgia Agric. Exp. Stn., The Univ. of Georgia, Athens.
- Ritchie, J.T., U. Singh, D.C. Godwin, and W.T. Bowen. 1998. Cereal growth, development and yield. p. 79–98. In G.Y. Tsuji, G. Hoogenboom, and P.K. Thornton (ed.) Understanding options for agricultural production. Kluwer Academic Publ., Dordrecht, The Netherlands.
- Russelle, M.P., W.W. Wilhelm, R.A. Olson, and J.F. Power. 1984. Growth analysis based on degree days. Crop Sci. 24:28–32.[Abstract/Free Full Text]
- Sangakkara, U.R., M. Liedgens, and A. Soldati. 2004. Root and shoot growth of maize (Zea mays) as affected by incorporation of Crotalaria juncea and Tithonia diversifolia as green manures. J. Agron. Crop Sci. 190:339–346.
- SAS Institute. SAS/STAT users guide. 2003. SAS Institute, Cary, NC.
- Schneider, E.C., and S.C. Gupta. 1985. Corn emergence as influenced by soil temperature, matric potential and aggregate size distribution. Soil Sci. Soc. Am. J. 49:415–422.[Abstract/Free Full Text]
- Soler, C.M.T., G. Hoogenboom, P.C. Sentelhas, and A.P. Duarte. 2007. Impact of water stress on maize grown off-season in a subtropical environment. J. Agron. Crop Sci. 193:247–261.
- Tracy, W.F. 2001. Sweet corn. p. 155–197. In A.R. Hallauer (ed.) Specialty corns. CRC Press, Boca Raton, FL.
- Twilley Seeds. Catalog for roadside, u-pick and bedding plant growers. 2004. Abbot & Cobb, Inc./Otis S. Twilley Seed Co., Hodges, SC.
- USDA-ERS. 2005. Commodity highlight: Fresh-market sweet corn. p. 1–5. In Economic Research Service (ed.) Vegetables and melons outlook.
- Verheul, M.J., C. Picatto, and P. Stamp. 1996. Growth and development of maize (Zea mays L.) seedlings under chilling conditions in the field. Eur. J. Agron. 5:31–43.[CrossRef]
- Warrington, I.J., and E.T. Kanematsu. 1983. Corn growth response to temperature and photoperiod I. Seeling emergence, tassel initiation, and anthesis. Agron. J. 75:749–754.[Abstract/Free Full Text]
- Williams, M.M., II, and J.L. Lindquist. 2007. Influence of planting date and weed interference on sweet corn growth and development. Agron. J. 99:1066–1072.[Abstract/Free Full Text]
- Wilson, D.R., and M.J. Salinger. 1994. Climatic risk for sweet corn production in Canterbury, New Zealand. N. Z. J. Crop Hortic. Sci. 22:57–64.
- Yan, W., and L.A. Hunt. 1999. An equation for modeling the temperature response of plants using only the cardinal temperatures. Ann. Bot. (Lond.) 84:607–614.[Abstract/Free Full Text]
- Yang, S., J. Logan, and D.L. Coffey. 1995. Mathematical formulae for calculating the base temperature for growing degree days. Agric. For. Meteorol. 74:61–74.
- Zaidi, P.H., S. Rafique, P.K. Rai, N.N. Singh, and G. Srinavasan. 2004. Tolerance to excess moisture in maize (Zea mays L.): Susceptible crop stages and identification of tolerant genotypes. Field Crops Res. 90:189–202.
TOP
ABSTRACT
INTRODUCTION
