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- Author or Editor: J. H. Edwards x
- Journal of the American Society for Horticultural Science x
Abstract
Peach [Prunus persica (L.) Batsch] seedlings of ‘Siberian C’, ‘Tzim Pee Tao’, NA 8, and 152A1–2 were grown for 64 days in nutrient solutions with constant N concentration, but the ratio of NO3 to NH4 in the nutrient solution varied from 100:0 to 0:100. The greatest growth occurred when the NO3:NH4 treatment was 50:50 or 25:75. The poorest growth occurred when NO3 was the sole N source in the nutrient solution. Significant interaction of nutrient concentrations occurred with the different rootstock and N ratios in all tissues studied. The N concentration in leaves and roots was highest in seedlings grown in N treatments of 100:0 or 75:25. The concentrations of P, Ca, and Mg in the leaves, stems, and roots of all cultivars decreased with each increment increase in the NH4 concentration in the nutrient solution. The relative growth rate and N uptake rate of all seedlings increased with high NH4 concentrations. The uptake rates of P, K, Ca, and Mg were highest for NO3:NH4 treatments of 50:50 or 25:75. Chlorosis developed on margins of leaves mid-way on the main stem on all seedlings with NO3:NH4 treatments 50:50, 25:75 and 0:100. The disorder occurred in the mature leaves of all cultivars but did not affect expanding leaves.
Abstract
Total nutrient content, uptake rates, and distribution were determined for seedlings of peach [Prunus persica (L.) Batsch] grown in nutrient solutions containing 0, 222, 666, and 2000 µ m Al. Generally, total nutrient content decreased in the peach seedling organs as Al concentration increased. The responses obtained with increased Al concentration were linear with some nutrients and curvilinear with others and varied with plant organ. As Al concentration increased, the uptake rates for P, Ca, Mg, Zn, and Mn decreased but those for K and Fe increased. Aluminum did not alter the translocation of most nutrients; however, a greater percentage of the absorbed Ca accumulated in the leaves than in the roots or stems. Thus, aluminum toxicity in peaches may be related to a reduction in Ca uptake rate and not to inhibition in translocation of Ca.
Abstract
‘Elberta’ and ‘Lovell’ peach seedlings (Prunus persica (L.) Batsch) were grown in nutrient solutions for 36 days with 0.8, 2.5, 7.5, 22.5, 67.5, and 202.5 μM Ca. At 0.8 μM Ca root growth was reduced, roots became brown, appeared gelatinous, and decayed before any foliar Ca deficiency symptoms developed. The Ca concentration in the external solution increased from 0.8 μM to 4.5μM Ca due to exchange of previously adsorbed Ca and efflux of Ca from the roots. Leaves wilted severely within 24 hrs and plants began to defoliate 5 days after initiating the 0.8 μM Ca treatment. Calcium deficiency symptoms in 2.5 μM Ca developed in the leaves as marginal chlorosis followed by necrosis that spread to the leaf apexes. Shoot tips died on some peach seedlings. Roots in 2.5 μM Ca died back severely and little regrowth occurred. Elongation of main and secondary roots was restricted and roots that developed were swollen and stubby. Reduced root growth was the only indication of Ca deficiency in seedlings grown in 7.5 μM Ca. No Ca deficiency symptoms appeared on seedlings grown in Ca concentrations greater than 7.5 μM.
Abstract
Seedlings of ‘Lovell’ and ‘Elberta’ peach [Prunus persica (L.) Batsch] were grown in the greenhouse for 29 or 50 days in nutrient solutions containing 8, 16, 33, 66, 132, 264, or 660 µM Ca at pH 4.5. Relative growth rate was unaffected by Ca concentrations. Calcium concentration in the stems was increased from 700 to 4330 µg/g dry weight and in the roots from 348 to 1787 µg/g dry weight by Ca treatments for the 29 days of growth. No Ca deficiency symptoms were observed on the seedlings when the Ca concentration in the leaves exceeded 2300 µg/g dry weight. The Ca uptake rates during the 29 days of growth for ‘Lovell’ increased from 0.46 to 3.77 and for ‘Elberta’ from 0.44 to 2.84 µmoles/g fresh-weight-root/day. After 50 days of growth, Ca uptake rates increased for ‘Lovell’ from 0.58 to 3.51 and for ‘Elberta’ from 0.52 to 3.02 µmoles/g fresh-weight-root/day. Calcium accumulated in stems when Ca concentration in the nutrient solution exceeded 264 µm Ca with no change in total Ca content in the roots. The K and P uptake rates were increased by higher Ca treatments but the Mn uptake rate was decreased when the Ca concentration in nutrient solution was greater than 66 µm.
Abstract
Seedlings of ‘Babygold 5’ peach [Prunus persica (L.) Batsch] were grown for 50 days in nutrient solutions with 0.4, 21, 42, 125, 250, 500 μm Mg. Magnesium deficiency symptoms were observed 19 days after initiation of the Mg treatments in the seedlings in 0.4 μm Mg solutions. The relative growth rate was significantly increased for the first increment of Mg concentration with no further increases at higher Mg concentrations. Increasing Mg in the nutrient solution significantly increased Mg concentration in the leaves, stems, and roots, but Mg tissue concentration decreased at all levels of Mg in the nutrient solution as physiological age increased. Visible Mg deficiency symptoms were observed on mature leaves at the 125 μm Mg treatment, but when the Mg concentration exceeded 250 μm, Mg concentration in mature leaves was increased above the threshold for appearance of Mg deficiency symptoms. No Mg deficiencies were observed on ‘Babygold 5’ seedlings when the Mg concentrations in the leaves exceeded 2000 μg/g dry weight and Mg uptake rate was 2.5 μmoles/g fresh wt./day.
Abstract
‘Elberta’ (Prunus persica (L.) Batsch) peach seedlings were grown in nutrient solutions for 27 days with aluminum concentrations of 0, 222, 666 and 2000 μ m; the 2000 μ m concentration induced A1 toxicity symptoms in leaves and severely restricted root growth. The early stage of A1 toxicity was characterized by marginal chlorosis that later developed into necrotic areas that extended along the veins toward the midrib. Advanced stages of toxicity were characterized by collapse of the midrib, terminal dieback and defoliation of the seedlings which are typical symptoms of calcium deficiency in peaches. At high A1 concentrations roots died back and new roots developed as irregularly shaped cylinders with constrictions and enlargements at the root apex.
Abstract
Nitrogen rate and in-row plant spacing significantly influenced yields of mechanically harvested red Tabasco (Capsicum frutescens L.) pepper. Red pepper yields increased with an increase in N rate from 0 to 112 kg N/ha, and a decrease in in-row plant spacing from 81 to 10 cm. The percentage of machine harvested red pepper in relation to green and orange fruit removal was enhanced with 20 cm in-row spaced plants. Tabasco plant height increased with an increase in N rate from 0 to 112 kg N/ha, while plant diameter decreased with a decrease in in-row spacing from 81 to 10 cm. Conventionally spaced (81 cm in-row spacing) Tabasco plants were damaged substantially more during mechanical harvesting than 10 cm in-row spaced plants. Early season leaf-petiole tissue N concentrations had higher correlations with red pepper yields than did late season tissue N concentrations. Multiple harvests of red Tabasco pepper with a flail-type machine produced yields similar to those obtained with hand harvesting.
Abstract
‘Redglobe’ peaches [Prunus persica (L.) Batsch] were grown under drip irrigation. Applications of NH4NO3 through the irrigation system were compared with broadcast applications. Soil pH, where NH4NO3 was applied through the irrigation system, decreased in the top 30 cm from 6.2 to 3.7 pH in the zone wetted by emitters that had been in place for 2 years, and from 6.2 to 4.5 pH in the zone where emitters had been in place for 6 months. Aluminum concentration in wetted zones increased from 0.01 to 1.45 meq/100 g of soil after 2 years and from 0.02 to 0.73 meq/100 g of soil after 6 months of NH4NO3 application through drip irrigation. Soil Ca and Mg concentrations were reduced in both wetted zones, but the greatest decrease occurred in the 2-year emitter site. The addition of NH4NO3 in the irrigation water substantially reduced root growth in the vicinity of the emitters, irrigation water application, and fruit yield, because of the high A1 concentration in the wetted zone.
Abstract
‘Redglobe’ peaches (Prunus persica (L.) Batsch) were grown under drip irrigation and no irrigation, with and without fumigation with 1,2–dibromo–3–chloropropane (DBCP). The irrigation treatments were 1) nonirrigated, 2) irrigated until harvest, 3) irrigated from harvest to dormancy, 4) irrigated all season. Fumigation increased trunk cross-sectional area by 18 cm2, and when postharvest water was applied the increase was 25 cm2 at the end of 1978. Irrigation increased marketable yields of fresh peaches from 3.6 to 7.4 MT/ha (62-150 bu/acre) in 1977. In 1978, fumigation did not increase yields unless preharvest water was applied; then, yields were increased from 12.1 to 17.2 MT/ha (232-357 bu/acre). Fumigation apparently increased water use as indicated by the increased rate of controlled water application. Fumigation reduced populations of Macroposthonia xenoplax (Raski) DeGrisse and Loof, from a range of 30-400 to a range of 1-30 nematodes/150 cm3 of soil.