Search Results
The performance of two sweet corn (Zea mays var. saccharata) cultivars grown in the Rio Grande Valley in Spring 1997 were evaluated under three tillage practices. On 25 Apr. 1997, `Champ' and `Sensor' seeds were sown on 0.76-m row centers of 4.6 x 91-m (12 x 300-ft) plots which had been in continuous conventional (CT), minimum tillage (MT), and/or no tillage (NT) since Aug. 1994. All production inputs were similar except tillage practice. Ears were harvested beginning 16 Jun 1997. Cultivars differed in leaf greenness, plant stand (P < 0.11), ear diameter, length, and dry matter, percentage of total yield at first harvest, season yield, and ears/ha. `Sensor' ears had higher concentrations (dry-mass basis) of total N, K, S, NO3, and B, but lower concentrations of Mg (P < 0.06), Ca, Fe, and Mn than did `Champ'. Amaranthus spp. weed populations were higher in `Champ' then in `Sensor' tillage treatments. MT and CT resulted in greater ear attributes, yield, ears/ha, and less corn earworm damage, lower ear S concentrations, and fewer total weeds/ha than corn grown with NT. Plant stand was highest in CT plots. Weed populations of Panicum and Amaranthus spp., but not Texas tridens [Tridens texanus (S. Wats.) Nash] or common purslane (Portulaca oleracea L.), were higher in NT-grown corn than MT- or CT-grown corn.
A reflectant particle film material, `Surround', which also has biocide properties, and mycorrhizal root inoculation of tomatoes at transplanting were evaluated for their efficacy in improving tomato plant water status and agronomic performance in a supra-optimal, semi-arid environment. Seven-week-old `Heatmaster' tomato plants (Lycopersicon esculentum Mill.) were transplanted with or without a VAM inoculant (Gomes intaradices, Schenk & Smith) on 19 Feb. 1999 into a Raymondville clay loam soil in Weslaco, Texas (Lat. 26°12'). One-half of the inoculated and one-half of the uninoculated plants were sprayed between 16 Mar. and 1 June with seven applications of `Surround.' The trickle-irrigated plots were 5.6 m2 in size and treatments replicated four times in a RCB design. Recommended cultural practices were followed, but no fungicides were used. Results indicated that mycorrhizal treatment tended to accelerate fruit maturation and that particle film applications delayed fruit development relative to the control treatment. Mycorrhizal-treated plants had the highest yields at the second (of eight) harvest compared to the other treatments. There were no significant differences between treatments in leaf temperature, diffusive resistance, transpiration rate, water potential, and soil profile moisture, except between sampling dates. Fruit mineral nutrients, pigments, dry matter, average weight, total marketable and total season yields were not significantly effected by any treatment. When fruits were sectioned into proximal and distal halves, 10 out of 14 nutrients measured, in addition to dry matter, and total carotenoids were higher in the distal end.
In Spring 1998, two sweet corn (Zea mays var. rugosa) cultivars were grown under three tillage systems, conventional cultivation, ridge tillage (RT), and no tillage (NT), which had been in continuous management since Fall 1994. Nitrogen (as NH4NO3), the only fertilizer used, was applied twice at 60 kg/ha. Sweet corn yields were not influenced by tillage system, but average ear weights tended to be smaller under NT (P < 0.17). Ear quality attributes, which included ear weight, length, diameter, dry matter, and incidence of earworm damage, were greater in the later-maturing `G-90' cultivar than in `Sensor'; but tillage system had no influence on these attributes. Cultivars supported different weed species underneath their canopies. `Sensor' allowed more light penetration and sustained higher weed biomass than did the taller `G-90' plants. Weed biomass was higher under RT and NT. Seasonal soil moisture was lowest in the RT plots, but only in the 0- to 15-cm profile. Soil temperatures (unreplicated) at the 15-cm depth were similar between cultivars and tillage treatments over the growing season. The earlier-maturing `Sensor' generally accumulated more ear mineral nutrients (P, S, NO3, Ca, Na, Zn, Mn, Al, and B; dry weight basis), but had lower dry matter (percentage) than did `G-90'. Cumulative nutrient levels tended to be lowest in NT-grown ears (P < 0.08). Soil sampled at 0- to 5-, 10- to 15-, and 25- to 30-cm depths generally had higher concentrations of nutrients toward the surface, and NT soils had the steepest nutrient gradients, with the exception of Na and NO3. Total soil salts were reduced by RT and NT, but C: N ratio remained unchanged between tillage systems.
Kaolin cover sprays and mycorrhizal inoculation of tomatoes at transplanting were evaluated for their efficacy in improving tomato plant water status and agronomic performance in a supraoptimal, semiarid environment. Seven-week-old `Heatmaster' tomato plants (Lycopersicon esculentum Mill.) were transplanted with or without a vesicular-arbuscular mycorrhizal inoculant (Gomes intaradices Schenk & Smith) on 19 Feb. 99 into a Raymondville clay loam soil in Weslaco, Texas (lat. 26°12′). One-half of the inoculated and one-half of the uninoculated plants were sprayed between 16 Mar. and 1 June with seven applications of the kaolin-based particle film “Surround.” The trickle-irrigated plots were 5.6 m2 in size and treatments replicated four times in a RCB design. Commercial cultural practices were followed, but no fungicides were used. Results indicated that mycorrhizal inoculation tended to accelerate fruit maturation and that particle film applications delayed fruit development relative to the control treatment. Mycorrhizal (only) treated plants had the highest yields at the second (of eight) harvests compared to the other treatments. There were no significant differences between treatments in leaf temperature, diffusive resistance, transpiration rate, water potential, and soil profile moisture, except between sampling dates. Fruit mineral nutrients, pigments, dry matter, average weight, total marketable and total season yields were not significantly affected by any treatment. When fruits were sectioned into proximal and distal halves, 10 out of the 14 nutrients measured, in addition to dry matter, and total carotenoids were higher in the distal end.
Twenty-one day old seedlings of a vegetable amaranth (RCC 241, Amaranthus tricolor) and a grain amaranth (K343, A. hybridus × A. hvpocondriacus) were transplanted on July 28, 1989. Equal applications of NH4N O3 were made on July 28 and August 25 to give total N rates of 0, 60, 120 and 240 kg/ha. Accessions were harvested on Oct. 18 and 14, respectively. Increasing N, induced a quadratic response in plant dry wt, seed wt/plant and seed size fractions in both amaranth types. Seed size fractions as a percent of the total seed, plant height and seed to plant dry weight ratio were not affected by increased N. Seed protein increased linearly whereas seed nitrate increased quadratically with increasing N application. Higher N rates increased residual soil NO3, NR4 and electrolytes and decreased pH. Decreasing soil pH appeared to reduce soil K and Cu but increase Fe and Mn availability. The effect of N rate on seed germination was inconclusive, but the larger seed size was higher in germination. There were differences among species in most responses tested. These data suggest that N applications be tailored to the season growing length required by the respective species/cultivar.
Twenty-one day old seedlings of a vegetable amaranth (RCC 241, Amaranthus tricolor) and a grain amaranth (K343, A. hybridus × A. hvpocondriacus) were transplanted on July 28, 1989. Equal applications of NH4N O3 were made on July 28 and August 25 to give total N rates of 0, 60, 120 and 240 kg/ha. Accessions were harvested on Oct. 18 and 14, respectively. Increasing N, induced a quadratic response in plant dry wt, seed wt/plant and seed size fractions in both amaranth types. Seed size fractions as a percent of the total seed, plant height and seed to plant dry weight ratio were not affected by increased N. Seed protein increased linearly whereas seed nitrate increased quadratically with increasing N application. Higher N rates increased residual soil NO3, NR4 and electrolytes and decreased pH. Decreasing soil pH appeared to reduce soil K and Cu but increase Fe and Mn availability. The effect of N rate on seed germination was inconclusive, but the larger seed size was higher in germination. There were differences among species in most responses tested. These data suggest that N applications be tailored to the season growing length required by the respective species/cultivar.
Abstract
Eight accessions of Amaranthus tricolor (amaranth) produced between 10.0 to 18.4 MT/ha of plant biomass. Leaf blades constituted between 40% to 62% and leaf tissue between 53% to 80% of the above ground fresh weight of these accessions. Collectively, leaf blades contained 1.1% NO3-N and 2.3% soluble oxalate (as percentage of leaf blade dry weight) and 11.4 mg/g (dry weight) chlorophyll. Average leaf blade elemental levels were 3.84% K, 3.47% Ca, 0.77% Mg, 0.44% P, 0.46% S, 593 ppm Fe, 562 ppm Al, 458 ppm Na, 282 ppm Mn, 79 ppm Zn, and 65 ppm Cu. Four accessions were judged by a taste panel to be comparable to spinach in organoleptic quality.
Abstract
Two levels of phosphorus (20 and 80 kg P/ha) and two levels of aluminum (0 and 85 kg Al/ha) were applied to Enders soils of pH 4.4, 6.6, or 7.3. Sixteen-day-old vegetable amaranth (Amaranthus tricolor L.) plants (Rodale Research Center Accession 241) were transplanted 24 July 1986 and harvested 27 days later. Increasing soil pH from 4.4 to 7.3 decreased plant height, fresh weight, leaf area, leaf blade chlorophyll, N, K, Mn, and Zn, but increased Ca, Mg, Al, and Na (dry-weight basis). Supplemental P increased plant height, leaf area, plant dry weight, leaf blade P, K, Ca, Mg, Na, and chlorophyll; decreased Fe, B, Zn, and Al; but had no effect on leaf blade protein. Adding Al to the soil decreased plant height, leaf blade chlorophyll, N, P, and Na, but increased Mn. At the termination of the experiment, exchangeable soil Al was found only in soil at pH 4.4 (1.1 cmol·kg-1). The highest leaf blade Al concentration (2473 mg·kg-1) was found in soil at pH 6.6 that received the low rate of supplemental P. Regardless of soil pH, leaf blade Al was negatively correlated with plant height (r = -0.78), plant dry weight (r = -0.78), available soil P (r = -0.51), and leaf blade P (r = -0.53), but it was positively correlated with Fe (r = 0.98).
Sulfate, as K2SO4, was applied to silt loam (Leadvale) soils of pH of 5.0 and 7.1 at rates of 0, 6, 18 and 36 kg S/ha. Nitrogen, as NH4NO3, was split applied at 0 and 120 kg/ha. All treatments received 55 and 45 kg/ha of P and K, respectively. Twenty day-old plants of accession RRC 241 were transplanted on 12 July 1990 and harvested 47 days later. Supplemental SO. had no effect on plant ht or yield but increased soil solution SO4 levels at the end of the season. Leaf blade N and S levels were increased at the highest SO4 rate. Higher SO4 rates increased leaf blade chlorophyll (chloro) `a', total chloro and total carotenoid levels. Response of leaf blade total sulfur, sulfate and organic sulfur to supplemental SO4 was linear. Organic to inorganic S ratios were unchanged. Plants grown at pH 5 had lower yields but higher leaf blade K, Al, Fe, Mn, Zn and Cu levels. Plants grown at pH 7 had higher leaf blade P, Ca, Na, and chloro levels. Soil pH did not effect soil solution SO4 levels. N reduced soil pH, and leaf blade P, Ca, Mg, Zn but increased soil electrolytes, leaf blade N, Na, Mn, chloro `a' and `b', and total carotenoids. Leaf blade N was the only leaf consituent from plants grown at both pHs correlated with leaf blade pigments.
`Jersey Giant' asparagus (Asparagus officinalis L.), grown in an Enders silt loam mineral soil, was given 80 kg supplemental N/ha either before or after the harvest season. Neither N application timing affected spear yield, objective color, or pigment concentration. Early supplemental N application decreased K concentration in white spears and Ca concentration in green spears. Green asparagus contained higher total-N, K, P, S, Ca, Mg, Fe, Zn, Al, Mn, and Cu concentrations but a lower soluble solids concentration (SSC) and NO3 than did white asparagus. As the cutting season progressed, spear SSC and S, Ca, NO3 (NO3 in white spears only), Zn, Mn, and Cu (Cu in white spears only) concentrations decreased, but spear K and Al (Al in white spears only) increased on a dry-weight basis. Fall residual soil NO3 levels were not affected by N application timing, but organic matter (percent) was lower in soil that received early supplemental N.