In a 3-year study with broccoli [Brassica oleracea var. botrytis (L.) Mill. cv. Green Comet], NP or NPK fertilizer at rates of 56N-56P-0K, 56N-56P-56K, and 56N-112P-56K (kg·ha-1) were banded in plots to which three types of lime had been applied—calcitic, calcitic with 3% Mg, or dolomitic. Fertilizer and lime controls were included. Previous liming had raised the soil pH from 5.3 to 7.2-7.4. Effects of lime on yields were greatest when no fertilizer was applied. Dolomitic lime was the most effective, increasing total yield by 49%, terminal weight by 54%, and hastening maturity. Fertilizer effects were most evident when no lime had been applied, with all fertilizer treatments increasing total yield, terminal and plant weight, and hastening maturity. Most changes occurred in the 56N-56P-OK treatment. Effects of lime when fertilizer was applied and effects of fertilizer when lime had been applied were less consistent. Lime alone, especially types containing Mg, increased leaf P, which generally followed the-same trend as total yield. Calcitic lime increased leaf Ca and dolomitic lime increased leaf Mg over other lime treatments. Calcitic lime with 3% Mg increased leaf Ca, but not leaf Mg, compared to the check. All lime treatments decreased leaf Mu, B, and Zn. Fertilizer treatments usually increased leaf N and Mn. Phosphorus uptake was increased by either lime or fertilizer application. Regression analysis strongly suggested that P was the element most responsible for yield increases.
K.T. Demchak and C.B. Smith
B.L. Goulart, K. Demchak, and W.Q. Yang
Previous experiments in the laboratory and the field have suggested that location of mycorrhizal infection within the rhizosphere of blueberry plants may depend on cultural practices that are being used. Furthermore, we have observed that rapidly growing roots, whether in solution culture or within petri dishes, appear to be less likely to become infected when inoculated. A preliminary experiment found higher levels of mycorrhizal infection in roots growing at a 5-cm depth of soil compared to roots growing just under the mulch layer. To further test this hypothesis, an experiment was designed to evaluate the infection intensity of highbush blueberry plants (Vaccinium corymbosum L.) at different locations within the rhizosphere on plants growing under varying cultural practices. Cultural practices included mulching (mulch vs. no mulch) and nitrogen level (0 and 120 g ammonium sulfate/plant). Four-year-old `Bluecrop' highbush blueberry plants subjected to these treatments were arranged in a complete factorial design with six replications at the Russell E. Larson Agricultural Research Center at Rock Springs, Pa. Mycorrhizal infection intensity was evaluated from roots sampled nondestructively using a 2.5 cm soil corer at the interface of the mulch and soil, and at soil depths of 3 and 15 cm from two locations 15 cm from the crown of each plant. Results will be discussed.
Wei Qiang Yang, Barbara L. Goulart, and K. Demchak
A field trial was conducted to investigate the effectiveness of soil fumigation on maintaining nonmycorrhizal status and the effect of mycorrhizal inoculation and preplant soil amendment on the growth of tissue-cultured highbush blueberry plants. Soil fumigation using a methyl bromide/chloropicrin (67/33) mixture at the rate of 560 kg·ha-1 was effective in maintaining nonmycorrhizal status for one growing season. Noninoculated control plants became infected during the second growing season. Field inoculation using a native Oidiodendron maius was successful, but plant growth was not significantly affected by mycorrhizal inoculation in either year. Rotted sawdust amendment, however, reduced plant growth in the first year but effects were no longer measurable in the second year. Soil fumigation and field inoculation could be used to establish mycorrhizal plants and nonmycorrhizal controls for future short-term field experiments.
Wei Qiang Yang, Barbara L. Goulart, K. Demchak, and Yadong Li
The ability of mycorrhizal and nonmycorrhizal `Elliott' highbush blueberry (Vaccinium corymbosum L.) plants to acquire soil N under different preplant organic soil amendment regimes (forest litter, rotted sawdust, or no amendment) was investigated in a field experiment using 15N labeled (NH4)2SO4. Plants inoculated with an ericoid mycorrhizal isolate, Oidiodendron maius Dalpé (UAMH 9263), had lower leaf 15N enrichment and higher leaf N contents than noninoculated plants but similar leaf N concentrations, indicating mycorrhizal plants absorbed more nonlabeled soil N than nonmycorrhizal plants. Mycorrhizal plants produced more plant dry weight (DW) and larger canopy volumes. The effect of preplant organic amendments on the growth of highbush blueberry plants was clearly demonstrated. Plants grown in soil amended with forest litter produced higher DW than those in either the rotted sawdust amendment or no amendment. Plants grown in soils amended preplant with sawdust, the current commercial recommendation, were the smallest. Differences in the carbon to nitrogen ratio were likely responsible for growth differences among plants treated with different soil amendments.
D.G. Mortley, C.B. Smith, and K.T. Demchak
The effects of fertilizer placement on growth and nutrient uptake of `Count II' tomatoes (Lycopersicon esculentum Mill.) were evaluated in a 3-year study. Fertilizer was applied broadcast at two rates or banded in two bands at two widths or in four bands, or applied in combinations of sidedressing or broadcasting with banding of N, P, and K at 56, 112, or 224 kg·ha-1 each. Total fruit yield for the 112 kg·ha-1 banded treatment was 24% higher than that for the same rate broadcast and similar to yield for 224 kg·ha-1 broadcast. Treatments involving combined placements, wider bands, or four bands produced yields similar to that for 112 kg·ha-1 banded, but the 56 kg·ha-1 banded with two 56 kg·ha-1 sidedressings had the highest yield. Leaf concentrations and plant contents of N, P, and K and percentage recovery of quantities applied were generally higher in treatments involving banding or sidedressing when compared to broadcasting. Leaf Mn was much higher in banded or sidedressed than for broadcast treatments but was lower when 112 kg·ha-1 was applied in four bands than in two. Only with Mg and Mn were leaf concentrations and plant contents highly correlated. With 112 kg·ha-1 banded, 31.2% of the N, 5.8% of the P, and 44.7% of the K applied were taken up, compared to 12.5%, 2.3%, and 17.2%, respectively, for double this rate broadcast.
B.L. Goulart, K. Demchak, W.Q. Yang, C.M. Stevens, and Y. Dalpe
Past experiments have proven that meristem tip-cultured blueberry plantlets are extremely difficult to inoculate using laboratory-grown cultures of existing known isolates of Hymenoscyphus ericae, Scytalidium vaccinii, and Oidiodendron griseum; fungi that have been previously established as ericoid mycorrhizal symbionts. An experiment using both seedling and meristem tip-cultured plantlets was conducted using these proven fungal symbionts from the Canadian Fungal Culture Collection (DAOM), as well as fungi isolated from local blueberry populations at Little Flat, Pa. Treatments included inoculation using soil from the Little Flat population, the same soil (autoclaved), autoclaved soil that was reinoculated with fungi, as well as axenic treatments using H. ericae, S. vaccinii, O. griseum, Little Flat Hymenoscyphus sp., Little Flat Scytalidium sp., and Little Flat Oidiodendron sp. Sampling after 21 days revealed that only the nontreated soil plantlets were infected (≈4%). Results from later sampling dates will be presented, and the mechanism of infection discussed.
J.F. Hancock, C.A. Finn, S.C. Hokanson, J.J. Luby, B.L. Goulart, K. Demchak, P.W. Callow, S. Serçe, A.M.C. Schilder, and Kim E. Hummer
An elite group of 38 strawberry accessions representing all subspecies of the beach strawberry [Fragaria chiloensis (L.) Miller] and the scarlet strawberry (F. virginiana Miller) was planted in a replicated design at five locations across the United States, and evaluated for plant vigor, flowering date, runner density, fruit set, fruit appearance, and foliar disease resistance. Considerable genotyp× location interaction was observed for many of these traits. However, a few genotypes were impressive at all locations including PI 551735 (FRA 368) with its unusually large, early fruit, and PIs 612486 (NC 95-19-1), 612493 (Frederick 9), and 612499 (RH 30), which were very vigorous and had unusually good fruit color. Genotypes that were superior at individual locations included PIs 551527 (FRA 110) and 551728 (Pigeon Pt.) in Maryland for their large fruit, and PI 612490 (Scotts Creek) in Oregon which had extremely large fruit, superior color, firmness, and flavor. The PIs 612495 (LH 50-4), 612498 (RH 23), and 612499 (RH 30) performed well as day neutrals at multiple sites.