Search Results

You are looking at 1 - 10 of 29 items for

  • Author or Editor: D. J. Makus x
Clear All Modify Search
Free access

D.J. Makus

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.

Free access

D.J. Makus

Three-week-old transplants of Amaranthus tricolor cultivars 'RRC 241' (RC) and 'Hinn Choy' (HC) were given split applications of supplemental N of 0, 100 and 200 kg/ha and in the 5th week after sowing were exposed to 100, 70 and 50% of ambient solar radiation for nine and ten days, respectively. Increased shading had a linear (L) effect on leaf blade NO3, protein, K, Mg, S, P, Al, Fe and Cu (dry wt basis). There were L and quadratic (Q) increases in chlorophyll (chloro) and carotenoids. Increasing supplemental N increased leaf blade protein (L,Q), Na (L), Mn (L), chloro (L,Q), carotenoids (L,Q), but decreased Mg (L), P (L,Q) and Zn (L,Q). Nitrate levels showed L and Q increases in RC and HC, respectively. HC was higher in leaf blade K, Mg, Na, Fe, Zn, Cu, NO3, chloro and carotenoides, but lower in CA than RC. Shading had no effect on leaf area or plant fresh wt, but decreased plant dry wt while increasing plant water content. Nitrogen application increased stem length, and plant fresh and dry wt.

Free access

D,J. MAKUS

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.

Free access

D.J. Makus

Mineral nutrients were determined in green and white `Jersey Giant' asparagus (Asparagus officinalis L.) spears grown in 1991 near Booneville, Ark. Green spears had higher concentrations of tissue N, K, P, S, Na, and Zn; similar levels of Fe, Al, and Cu; and lower levels of NO3 than white spears grown under opaque plastic rowcovers or under sawdust mulch. Levels of Ca, Mg, and Mn were higher in plastic-grown white spears than in those grown in sawdust. The spear tip contained higher concentrations of K, S, and Cu than the butt. Less NO3, Fe, and Al were in the tip than in the butt. Spear distribution gradients for K, Fe, and Cu were linear, whereas S and NO3 gradients were both linear and quadratic. Nitrogen, P, Ca, Mg, Zn, Al, and Mn levels were influenced by spear production method and spear segment.

Free access

D. J. Makus

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.

Free access

D. J. Makus

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.

Free access

D. J. Makus

On 3 Aug. 1993, 20-day-old `Hinn Choy' plants (Amaranthus tricolor L.) were-planted on 15 × 15 cm spacings in 4-row beds at 1.3 m row spacings in a Leadvale silt loam soil. Nitrogen sources of NH4, NO3 and NH4 NO3 were used at rates of 0, 100 and 200 kg/ha, and were split-applied at and 1 week after transplanting. All treatments received both supplemental K and P at the rate of 90 kg/ha at planting. Plants were harvested 31 days after transplanting. Plants given the NH, source were taller, and were higher in yield, leaf chlorophyll, total carotenoids and Mn (dry wt basis) than were plants given other N-sources. NO3-N fertilizer increased leaf Fe and Cu, and residual soil K and NO3, but reduced Mn levels. Leaf blade Ca was highest when NH4NO3 fertilizer was used. Increasing N-rates decreased both soil pH linearly and leaf blade Ca but linearly increased soil EC, NO3, and S and leaf blade N, K, S, P, NO3, Fe, chlorophyll and carotenoids.

Free access

D. J. Makus

`Jersey Giant' asparagus (Asparagus officinalis L.), grown in an Enders silt loam mineral soil near Booneville, Ark., was given an application of 80 kg/ha of Supplemental nitrogen (N, as NH4N O3) either prior to or after the Cutting season in 1993. Neither N treatment affected spear objective Color, Pigments, soluble solids concentration (SSC), or yield. Supplemental N decreased spear Ca and K levels. Green asparagus had higher levels of total-N, K, S, P, Ca, Mg, Fe, Zn, Al, Mn, and Cu, but lower levels of NO3 than did white asparagus. As the Cutting season progressed, spear SSC, S, Ca, NO3 (NO3 in White spears only), Zn, Mn, and Cu (Cu in white spears Only) levels decreased, While 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, but organic matter was lower in soil which received early supplemental N.

Free access

D.J. Makus

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.