NIR-based tissue analysis has proven useful in Australia for making fertilizer recommendations for rice and wheat growers. Viticulturists have for some time made fertilizer recommendations based on tissue analysis, although there is some debate in the literature as to whether younger or older leaves or petioles provide the best indicator of vine nutrient status for diagnostic purposes. The aim of our research has been to develop NIR-based nutrient analysis for grape producers. Aspects of sample collection, including leaf lamina vs. leaf petiole; leaf opposite the basal cluster vs. youngest leaf; aspects of drying (microwave vs. convection oven), have been reexamined from the viewpoint of convenience, cost, accuracy, and turnaround time with respect to NIR analysis. We have refined procedures for collecting and microwave-drying samples. The samples of leaves and petioles were collected from vines in most wine-growing regions of Australia and included all the major wine grape and some dried fruit cultivars on their own and, in some cases, on rootstocks. At this stage, we have developed preliminary NIR calibrations for the major nutrient elements in both leaf lamina and petioles.
All leaves from 10 replicate Cocos nucifera L. `Malayan Dwarf' (COC) and Phoenix canariensis Chabaud (CID) trees were sampled for leaf nutrient analysis. In addition, the leaflets of the youngest fully expanded leaves and the third oldest leaves were divided into five groups along the primary leaf axis and these leaflets were then cut into thirds to determine nutrient distribution patterns within leaves and leaflets. Nutrient remobilization rates were calculated for N, P, K, Mg, and Mn. Results showed that N, P, and K were highly mobile within and between leaves of both species of palms. Up to 31% of the N, 66% of the K, and 37% of the total P in the oldest leaves were ultimately remobilized to newer leaves within the palm. Magnesium remobilization rates averaged ≈71% for CID but only ≈10% for COC. The middle-aged leaves appeared to be the primary sink for Mg in COC, rather than the youngest leaves as in CID. Manganese was also quite mobile in both species, with up to 44% of the total Mn remobilized in CID. Samples consisting of recently matured leaves were determined to be the most appropriate for Ca, Fe, Mg (COC only), and Zn, but oldest leaves are more suitable for N, P, K, and Mn analysis.
Nutrient uptake and allocation patterns of Forsythia ovata × europaea `Meadowlark' grown in a recirculating hydroponic system in the greenhouse were observed for 5 months. Dormant rooted cuttings were placed in the system on 8 May 1995. The nutrient solution supplied (in mg·L–1) 100 N, 48 P, 210 K, 30 Mg, 60 Ca, 117 SO4, 3 Fe, 0.5 Mn, 0.15 Zn, 0.15 Cu, 0.5 B, 0.1 Mo. Solutions were completely replaced every 2 weeks. Leaves, stems, and roots were harvested for dry weight and nutrient analysis at monthly intervals. Nitrogen uptake and dry-weight accumulation in the roots increased throughout the experiment, reaching a maximum in the fifth month (September). Nitrogen uptake and dry-weight accumulation of leaves and stems increased rapidly throughout the first 3 months, then leveled off. Whole-plant N recovery (N taken up/N in hydroponics system) reached a maximum (58%) between 6 July and 3 August. N recovery in the hydroponics system was about 10 times greater than what we observed in related experiments with woody plants in typical production environments, suggesting that there is potential for manipulating fertilization and cultural practices to increase fertilization efficiency in woody ornamentals. Nutrient recovery and accumulation patterns of P and K also will be presented.
Cultivar may cause variation in arbuscular mycorrhizal fungi (AMF) colonization levels leading to differences in shoot growth and runner formation, and in pathogen control in strawberries. However, a clear consensus has not been reached regarding the degree to which cultivar affects the formation of the symbiosis or its functioning. The study was conducted on four commercial strawberry farms in Minnesota and Wisconsin to compare, within a farm, mycorrhizal colonization and plant response among three strawberry cultivars: `Winona', `Anapolis' and `Jewel'. At each farm, two 6 × 6 meter plots of each cultivar were randomly selected. On each of three sampling dates, 4 whole plants and soil samples were collected from these plots in the 2003 field season. Roots were separated from shoots and leaves, and fresh and dry weights were taken. Leaves and soil were dried, weighed, and submitted for nutrient analysis. Soil nutrient analyses include phosphorus (Bray P), potassium, pH, buffer pH and organic matter. Leaf tissue analyses include P, K, Ca, Mg, Na, AL Fe, MN Zn, Cu, B, Pb, Ni, Cr, and Cd. Roots were collected, frozen, and prepared for scoring using methods adapted from Koske and Gemma (1989). Presence of mycorrhizal colonization is being scored using the methods of McGongle et al. (1990). Levels of mycorrhizal colonization among different strawberry cultivars will be compared. We will also use biomass measurements, to determine mycorrhizal effects on plant growth among different cultivars. Soil and leaf analysis data will be used to determine effects of AMF on plant nutrition and compare effects among cultivars.
The influence of three irrigation treatments on flowering, yield, tree growth, root distribution, and leaf analysis of mature `Hass' avocado (Persea americana Mill.) was investigated over a six year period (1987-1992). Three irrigation treatments; 60, 80, and 100% of evapotranspiration (ETc) were applied using low-volume spray emitters. The differential irrigation treatments were maintained year round. Irrigation treatments did not affect the timing or intensity of bloom. Yield data from years 2-6 show a significant irrigation effect on cumulative weight and total number of fruit per tree. Trees receiving 100% ETc had higher yield/tree. This increased yield was due both to increased fruit numbers and individual fruit weight per tree. Tree growth was also significantly impacted by the irrigation treatments. Trees receiving 100% ETc exhibited the greatest amount of vegetative growth over the study. Yield efficiency (Kg fruit/m3 canopy) was not influenced by irrigation treatment. Irrigation treatment did not significantly influence nutrient analysis taken in the fall of each year.
Growth and mineral nutrient content of creeping bentgrass [Agrostis stolonifera (L.) var. palustris (Huds.) Farw.] in response to salinity and humic acid (HA) application were investigated, and the effects of HA application on salinity tolerance was evaluated. Bentgrass plugs were grown hydroponically in one-quarter-strength Hoagland's nutrient solution containing HA at 0 or 400 mg·L-1 with salinity levels of 0, 8.0, or 16.0 dS·m-1. Clipping dry weight (DW), tissue water content, and net photosynthesis (PN) were measured weekly for 1 month. Maximum root length, and root DW from 0 to 10 cm and >10 cm root zones were determined 31 days after treatment (DAT). The turfgrass plugs were mowed three times weekly, with clippings collected and dried for mineral nutrient analysis. Salinity was inversely related to clipping DW, tissue water content, PN, and maximum root length. Salinity had less effect on root growth than top growth. HA treatment did not affect tissue water content, PN, or root growth of salt-stressed turf. Salinity decreased uptake of N, P, K, Ca, and S; increased uptake of Mg, Mn, Mo, B, Cl, and Na; and had no influence on uptake of Fe, Cu, and Zn. Application of HA at 400 mg·L-1 during salinity stress neither increased uptake of the mineral nutrients inhibited by salinity, nor decreased uptake of nutrients which were excessive and toxic in the salinity solution. In general, application of HA did not improve salinity tolerance of creeping bentgrass.
Horticulturists are often interested in evaluating the effect of several treatment factors on plant growth in order to determine optimal growing conditions. Factors could include three or more nutrient elements, or types and rates of irrigation, pesticides or growth regulators, possibly in combination with one another. Two problems with such experiments are how to characterize plant response to treatment combinations and how to design such experiments so that they are manageable. The standard statistical approach is to use linear and quadratic (a.k.a. response surface) regression to characterize treatment effects and to use response surface designs, e.g., central-composite designs. However, these often do a poor job characterizing plant response to treatments. Hence the need for more generally applicable methods. While our goal is to be able to analyze three and higher factor experiments, we started by tweaking two-factor nutrient analysis data. The result was a hybrid model which allows for a given factor to respond linearly or non-linearly. We will show how this was done and our current “in progress” model and analysis for analyzing three quantitative factors.
We are interested in understanding the molecular changes that occur in response to phosphate starvation in the roots of tomato plants. Aeroponics offers a unique way to study the changes that occur in the roots of plants. Tomato plants were grown in an aeroponic system developed by L.A. Peterson at the Univ. of Wisconsin. Aeroponically grown tomato plants were treated with various concentrations of phosphate (Pi) ranging from 0 to 250 μm. Plants were harvested at different times after the initiation of Pi deficiency treatments for nutrient analysis and gene expression studies. Several changes in essential nutrient content were observed. A differential accumulation of magnesium between the root and shoot tissue of phosphorus-starved plants was noticed. The expression of a recently cloned phosphate starvation induced gene (TPSI1) increased with decreasing concentration of Pi in the growth media. There is a strong correlation between the concentration of the Pi in the growth media and expression of the gene. The effect of Pi starvation on the gene expression in different parts of the plant, including old and young leaves, will be discussed.
Pure and biculture stands of rye `Wheeler' (Secale cereale L.) and field pea (Pisum sativum L.) were established and killed for mulch in Spring 1996, 1997, and 1998, in Columbus, Ohio. Treatments were five rye to pea proportions, each with a high, medium, and low seeding rate. Their effects on tomato (Lycopersicon esculentum Mill.) growth and yield were compared with those of a weedy check; a tilled, nonweeded check; and a tilled, hand-weeded check. Tomato tissue and soil were sampled for nutrient analysis. Number of leaves, branching, height, leaf area, dry weight, rate of flowering and fruit set, and fruit yield of tomato plants varied directly with the proportion of pea in the cover crop and decreased with reduced cover crop seeding rates. In 1997, yields of tomato were as high as 50 MT·ha-1 in the 1 rye: 3 pea cover crop; yield was poorest in the weedy check (0.02 MT·ha-1 in 1996). Most of the cover-cropped plots produced better yields than did the conventionally weeded check. No consistent relationship between levels of macronutrients in tomato leaf and soil samples and the cover crop treatments was established. Spring-sown rye + pea bicultures (with a higher ratio of pea) have a potential for use in tomato production.
Home gardening is a popular year-round recreational activity in Hawaii that helps to increase community food security in suburban and rural communities where high levels of poverty and unemployment exist. Updated fertilizer recommendations and accurate information about the latest products allows home gardeners to improve crop growth, and to minimize nutrient imbalances in the soil, pest problems, and environmental risks from nutrient runoff or leaching. Two field experiments were conducted in Oahu, Hawaii, to evaluate several new products in the market for the production of two home-garden Chinese cabbage varieties. The treatments included Miracle Grow, a new Miracle Grow Plus formulation, Plant Power 2003 nutrient solution, a Maui Liquid Compost product, and a standard fertilizer control (150 kg·ha-1 N rate). Each treatment consisted of a 6-m long row with 30-cm plant spacing in the row. Each treatment was replicated four times in a completely randomized block design, for a total of 40 plots (two varieties × five treatments × four replications). Data collected included soil fertility before initiation and after experiment completion, tissue nutrient analysis, plant height collected twice during the growing cycle, and head weight and length measured at harvest time. The variety Pagoda was more responsive to fertilizer applications, showing an average of 30% yield increases between the best and poorest treatment, compared to 20% for `China Express'. Overall, the Miracle Grow formulations outperformed the other products. The tissue nutrient data showed tissue nutrient levels above those recommended by the Extension Service. The treatments with highest yield response also showed greater symptoms of “black heart” from possible boron deficiency.