Fall and spring collards (Brassica oleracea L. Acephala Group) were grown under one of three mulches (black plastic, ground newspaper, wood chips) and in a bare soil control. Mulch treatments were arranged in a factorial design with five rates of N fertilizer: 0, 67, 134, 201, or 268 kg N/ha. All fertilizer was preplant-incorporated into the bed before applying mulches and transplanting collards. Season did not affect collard yield, and there was no significant season × N rate interaction. Collard yields increased with increasing rates of N, with a maximum yield at 163 kg N/ha. Mulch type significantly affected collard yield, with fall collard yields highest under bare ground or wood chip mulches and spring yields highest under black plastic mulch. Collards produced under newspaper mulch produced the lowest yields in the fall and yields equal to bare soil and wood chips in the spring. Collards produced under newspaper mulch had less tissue N at harvest than those of any of the other treatments in both seasons. Collards produced on black plastic produced the lowest plant populations in both seasons. Wood chips and newspaper offer some appeal as low-input, small-scale mulches, but additional research to explore fertility management is necessary.
A greenhouse pot study was conducted with a Wynnville sandy loam surface soil to determine the influence of application rates of poultry litter (PL) on growth and nutrient uptake of collard (Brassica oleracea, Acephata Group L., cv. Champion), and the residual effects of PL on growth and nutrient uptake of cabbage (Brassica oleracea, Capitata Group L., cv. Rio Verde). PL at 0, 13, 26, 53, and 106 g·kg–1 was incorporated into limed (pH 6.5) and nonlimed (pH 5.2) soil. Collard plants were grown for 52 days. The residual effects of PL were evaluated by growing three successive crops of cabbage without further application of PL (total 218 days). Collard plants were severely damaged or killed within 7 days after transplanting when the application rate of PL exceeded 26 g·kg–1 soil. Maximum dry matter yield of cabbage shifted from 26 to 106 g PL/kg soil during three successive crops. After four successive growth periods, 6% to 37% of N, 3% to 62% of Ca, 20% to 120% of K, 5% to 60% of Mg, and 3% to 25% of P added through PL was removed by plants. The decrease in water-extractable K accounted for the decrease in the soil salinity. Our results suggest that application rates of PL ≥ 53 g·kg–1 soil can result in elevated levels of salts and NH3 in soil, which can produce severe salt stress and seedling injury.
Aluminum concentrations of 0, 3, 10, 30, and 100 ppm in nutrient solution reduced proportionately the dry weights of stem, roots, and leaves of seedlings of ‘Lovell’ peach [Prunus persica (L.) Batsch]. Roots grown at 30 and 100 ppm A1 were shorter, thicker, and had less branching than roots grown at lower concentrations. The epidermal and endodermal cells were small, with grossly thickened cell walls. Cells of the cortex were shortened in the longitudinal axes. Leaf A1 level indicated solution A1 better than did the A1 levels of roots, stems, or the 2% acetic acid-extractable A1 fraction of leaves, stems, or roots. The concentration of Ca, Mg, Mn, and P were reduced as A1 concentration increased.
Peach (Prunus persica (L.) Batsch) seedlings were grown in nutrient solutions containing 0, 222, 666, 1333 or 2000 μM Al. Diffusive resistance (DR) increased as Al concentrations increased and were significantly higher at 2000 μM Al than at lower concentrations. Stomatal apertures were larger on seedlings grown in 666 μM than those in 222 or 1333, those of the check were smaller, and those in 2000 μM Al were the smallest. Root volume decreased as Al concentrations increased. Changes in DR appeared to be more closely related to root volume than to stomatal aperture or density.
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 µm 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.
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.
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.
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.
‘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.
Two studies were conducted to evaluate recycled newspaper mulch for landscape plantings. In the first study, two paper products (pellets and crumble) were tested at three depths. Application of either 25 or 50 mm provided excellent control of prostrate spurge. Of the four annuals grown, ageratum exhibited severe stunting of roots and shoots. In the second study, three annual species were mulched with the two recycled paper products applied at 25 mm each and adjusted with P at 0, 3.75, or 7.5 ppm to bind excess Al. When no P was added, ageratum growth was about half that of the control plants. Addition of P at either rate resulted in similar growth compared to control plants. Marigold and geranium were less affected by recycled paper mulch; however, when P was added growth was always similar to nonmulched control plants.