Search Results

You are looking at 1 - 8 of 8 items for

  • Author or Editor: John M. Swiader x
Clear All Modify Search
Free access

John M. Swiader and William H. Shoemaker

Field experiments were conducted over a 5-year period (1994-98) to determine the effect of various cropping systems (rotations) on fertilizer N requirements in processing pumpkins [Cucurbita moschata (Duchesne ex Lam.) Duchesne ex Poir.] on medium- to fine-textured soil. Treatments consisted of a factorial combination of five N fertilization rates (0, 56, 112, 168, 224 kg·ha-1 N) and four pumpkin cropping systems: 1) pumpkins following corn (Zea mays L.); 2) pumpkins following soybeans [Glycine max (L.) Merrill]; 3) pumpkins following 2-years corn; and 4) pumpkins following fallow ground. Cropping systems were chronologically and spatially arranged in two complete cycles, with pumpkin studies taking place in 1996 and 1998. Averaged over the two studies, the optimal N fertilization rate for highest total weight of ripe fruit following soybeans was estimated at 109 kg·ha-1 N, compared to 128 kg·ha-1 N following fallow ground, even though yields were similar, suggesting a soybean N-credit of 19 kg·ha-1 N. Concurrently, the N fertilizer rate for highest total ripe fruit weight following corn was estimated at 151 kg·ha-1 N, and 178 kg·ha-1 following 2-years corn, indicating a negative rotation effect on pumpkin N requirements of 23 and 50 kg·ha-1 N, respectively. Minimum N fertilizer requirements, the N fertilizer rate associated with a ripe fruit yield of 50 t·ha-1, were calculated at 45, 37, 69, and 47 kg·ha-1 N in the respective cropping systems. Negative effects from excessive N fertilization were greater in pumpkins following soybeans than in pumpkins following corn or 2-years corn, with reductions in total ripe fruit weight of 21%, 9%, and 3%, respectively, at the highest N rate. A critical level for preplant soil NO 3-N of 17.6 mg·kg-1 was identified above which there was little or no pumpkin yield response to N fertilization.

Free access

John M. Swiader and William H. Shoemaker

Field studies were conducted in 1994 and 1995 to evaluate the effects of in-furrow-placed (i.e., applied directly in the seed channel) starter fertilizer on the emergence, maturity, and yield response of early sweet corn. In both years, three starter fertilizer treatments were applied: APP, with N and P at 13 and 19 kg·ha-1, respectively (13N—19P kg·ha-1), either banded (5 cm below and 5 cm to the side of the seed) or placed in-furrow, and a control (no starter fertilizer). Additionally, in 1995, the rate of APP was increased to supply 26N—38P kg·ha-1 in combination with either band (5 × 5 cm) or in-furrow placement. Seedling emergence was delayed whenever starter fertilizer was applied with the seed; however, significant reductions (≈21%) in plant stand occurred only at the high rate of in-furrow placement. In both years, all starter treatments had a positive effect on seedling dry-matter production, and hastened silking. In-furrow application of 13N—19P kg·ha-1 increased marketable ear yields 34% in 1995, but had no effect in 1994. Lack of yield response to the high rate of in-furrow fertilizer in 1995 was primarily a function of reduced stand, as ear number and ear mass per plant, and average ear size were similar to those in the other starter treatments. Based on these results, in-furrow APP at 13N—19P kg·ha-1 appears to be an effective starter fertilization regime for early sweet corn, comparable in effect to banded 26N—38P kg·ha-1. However, high rates of in-furrow APP may reduce stands. Although significant yield response to in-furrow starter fertilizer may not always be realized, the increased early seedling growth may itself be a benefit, since fast-growing seedlings are more likely to be tolerant of adverse environmental conditions than are less vigorous plants. Chemical name used: ammonium polyphosphate (APP).

Free access

Khalid Al-Redhaiman and John M. Swiader

The objective of this study was to investigate the effect of solution \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{NO}_{3}^{-}\) \end{document}concentration (Ns), in a recirculating hydroponic system, on the accumulation and partitioning of \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{NO}_{3}^{-}\) \end{document}and reduced N, and its relationship to root and leaf nitrate reductase activity (NRA), in five lettuce (Lactuca sativa L.) cultivars differing in \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{NO}_{3}^{-}\) \end{document}accumulation capacity. Significant interactions between Ns and genotype influenced \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{NO}_{3}^{-}\) \end{document}accumulation, reduced N levels, and NRA in roots and leaves. In two cultivars, leaf \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{NO}_{3}^{-}\) \end{document}concentrations increased with increasing Ns up to 5.0 mM, and then leveled off, while in three other cultivars, leaf \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{NO}_{3}^{-}\) \end{document}levels increased linearly with increasing Ns rate up to 15.0 mM. NRA in leaves was generally highest at 5.0 mM Ns, and tended to decrease at 15.0 mM Ns. In roots, NRA increased with increasing Ns rate up to 1.0 mM, and remained relatively constant as Ns increased to 5.0 and 15.0 mM. In each cultivar, in situ \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{NO}_{3}^{-}\) \end{document}reduction (estimated by the relative concentrations of tissue reduced N to total N) decreased in both roots and shoots as Ns increased. The results suggested that genotypic variation in \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{NO}_{3}^{-}\) \end{document}accumulation in response to increasing Ns was not exclusively a result of cultivar differences in \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{NO}_{3}^{-}\) \end{document}uptake and reduction capacity, but may also involve other factors in relation to \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{NO}_{3}^{-}\) \end{document}accumulation.

Full access

John M. Swiader and William H. Shoemaker

Field studies were conducted in 1994 and 1995 to evaluate the effects of in-furrow-placed (i.e., applied directly in the seed channel) starter fertilizer on the emergence, maturity, and yield response of early sweet corn. In both years, three starter fertilizer treatments were applied: APP, with N and P at 13 and 19 kg·ha-1, respectively (13N-19P kg·ha-1), either banded (5 cm below and 5 cm to the side of the seed) or placed in-furrow, and a control (no starter fertilizer). Additionally, in 1995, the rate of APP was increased to supply 26N-38P kg·ha-1 in combination with either band (5 × 5 cm) or in-furrow placement. Seedling emergence was delayed whenever starter fertilizer was applied with the seed; however, significant reductions (≈21%) in plant stand occurred only at the high rate of in-furrow placement. In both years, all starter treatments had a positive effect on seedling dry-matter production, and hastened silking. In-furrow application of 13N-19P kg·ha-1 increased marketable ear yields 34% in 1995, but had no effect in 1994. Lack of yield response to the high rate of in-furrow fertilizer in 1995 was primarily a function of reduced stand, as ear number and ear mass per plant, and average ear size were similar to those in the other starter treatments. Based on these results, in-furrow APP at 13N-19P kg·ha-1 appears to be an effective starter fertilization regime for early sweet corn, comparable in effect to banded 26N-38P kg·ha-1. However, high rates of in-furrow APP may reduce stands. Although significant yield response to in-furrow starter fertilizer may not always be realized, the increased early seedling growth may itself be a benefit, since fast-growing seedlings are more likely to be tolerant of adverse environmental conditions than are less vigorous plants. Chemical name used: ammonium polyphosphate (APP).

Free access

Adamson D. Wang, John M. Swiader and John A. Juvik

Dimethyl sulfide (DMS) has been identified as the compound responsible for the characteristic aroma of cooked sweet corn (Zea mays L.) and, along with sugar and water-soluble polysaccharides, is one of the main flavor components in the kernels. Because of the close relationship between DMS and its amino acid precursor S-methylmethionine, the premise was formulated that it might be possible to improve sweet corn aroma and overall eating quality through enhanced production of DMS from increased application of N and S to the crop in the field. Studies were conducted on a Plainfield sand and a Flanagan silt loam to evaluate the effects of N and S fertilization on kernel DMS production in several commercial sh2 hybrids; in the process, the effect of N and S fertilization on various yield and yield component parameters was also determined. Hybrid was the main factor affecting kernel DMS production, although in both soils kernel DMS levels were influenced by significant interactions between hybrid and fertilizer treatments. Kernel DMS content, in response to increasing N fertilization rates, increased by an average of 85% in three of six hybrids in the Plainfield sand and by 60% in two of three hybrids in the Flanagan silt loam. The effect of S fertilization on kernel DMS production was small, with only one hybrid on the sandy soil showing a positive response (38%) to S application, and then in combination with high N rates. Irrespective of N-S fertilization regime, kernel DMS concentrations decreased at both locations by an average of ≈8.5% per day as kernel maturity increased. The results showed that kernel DMS production may be enhanced by N nutrition, independent of N fertilization effects on ear and kernel yields.

Free access

Brian K. Hogendorp, Raymond A. Cloyd and John M. Swiader

Although silicon is not an essential element, it is taken up by plants but is rarely quantified. Therefore, this study quantified the silicon concentration in 10 commonly grown horticultural plants including meadow sage (Salvia ×sylvestris), tickseed (Coreopsis verticillata), garden phlox (Phlox paniculata), New England aster (Symphyotrichum novae-angliae), Chinese astilbe (Astilbe chinensis), coral flower (Heuchera hybrid), garden zinnia (Zinnia elegans), French marigold (Tagetes patula), sweet basil (Basil spp.), and rosemary (Rosmarinus officinalis) using a plant alkaline fusion technique, which involved dry-ashing plant tissue samples and measuring color development with a spectrophotometer. Both zinnia and aster accumulated substantially more silicon from the municipal water source and growing medium (5365 and 4797 mg·kg−1 silicon, respectively) than the other plants evaluated, which had concentrations less than 2500 mg·kg−1 silicon. This study is just one of a few in which the silicon concentration in various horticultural plants has been quantified. Consequently, this may lead to better understanding those plants that will or will not benefit from applications of silicon-based fertilizers to promote cold-hardiness and/or plant resistance to fungal pathogens and insect pests.

Free access

John M. Swiader, Stanley K. Sipp and Ronald E. Brown

Field studies were conducted in 1987 and 1988 to determine the effect of various sprinkler-applied N-K fertigation treatments and 196N-280K (kg·ha-1) dry-blend application on pumpkin (Cucurbita moschata Poir.) flower development, fruit set, vine growth, and marketable yield response in a Plainfield sand. The number of male and female flowers that reached anthesis by 72 days after seeding (DAS) was highest with either 112N-112K or 112N-224K fertigation. Fertigation using either 56N-112K or 168N-224K delayed the start of flowering and reduced the total number of male and female flowers produced by 72 DAS. Fruit set decreased at the low N-K fertigation rate (56N-112K), but otherwise was unaffected by N-K fertility regime. Vine dry weight and stem elongation increased as the N fertigation rate increased, with relatively little effect from fertigated K. There was no field indication of excessive vegetative growth in any of the fertigation treatments. Highest yields of early set marketable fruit (pumpkins that set before 65 DAS), and total marketable yields were obtained with fertigation of 112N, in combination with either 112 or 224 kg·ha-1 fertigated K. Usable green and cull fruit production increased with increasing N-K fertigation rate. Dry-blend application of 196N-280K decreased early and total yields significantly. The results showed that sprinkler-applied 112N-112K split into five fertigations during the growing season (supplemented with a preplant dry-blend application of 28N-56K) produced high yields without compromising early fruit maturity.

Free access

Adamson D. Wong, John A. Juvik, David C. Breeden and John M. Swiader

Extensive variability was found among 24 currently available commercial sh2 hybrids of sweet corn (Zea mays L.) for yield and yield components, and for the chemical components of eating quality. The primary source of variation was explained by genotypic differences, with the environmental effects due to planting locations having a minor influence. Kernel sugar concentrations, however, had a highly significant level of genotype by environment interaction. The extensive genotypic variability among the sh2 hybrids indicated that allelic variation at other loci is profoundly influencing sucrose and total sugar levels in freshly harvested sweet corn. In each case, the kernel chemical components of quality decreased from 20 to 29 days after pollination (DAP). Mean performance of sh2 hybrids for yield, yield components, and kernel quality parameters was in all cases equal or better than the hybrids homozygous for the su1 endosperm mutation. In addition, there were no strong negative relationships between yield and some of the important chemical components of kernel quality, suggesting that it may be feasible to develop superior sh2 hybrids with acceptable yield potential and improved eating quality targeted for the different sweet corn markets.