Search Results

You are looking at 21 - 28 of 28 items for

  • Author or Editor: Leonardo Lombardini x
Clear All Modify Search

Wilting during shelf life is a major cause of postharvest shrink for bedding plants shipped long distances from production greenhouses to retail outlets. The objective of this research was to determine if irrigation at lower, constant substrate moisture content (SMC) during greenhouse production would be a feasible way to acclimate plants for reduced shrinkage during shelf life while potentially conserving irrigation water. In two separate experiments conducted in the fall and spring seasons, rooted plugs of Angelonia angustifolia ‘Angelface Blue’ (angelonia) were grown in greenhouse production until a marketable stage in substrates irrigated at SMC levels of 10%, 20%, 30%, and 40% using a controlled irrigation system. At the end of the greenhouse production stage, plants were irrigated to container capacity and subjected to a simulated shipping environment in shipping boxes in the dark for 2 days. After shipping, plants were placed back in the greenhouse and watered minimally to simulate a retail environment. Data were taken at the end of each stage, i.e., greenhouse production, simulated shipping, and simulated retail. Results indicated that as SMC decreased from 40% to 10%, plants were shorter in height but had proportional and more compact flowering sections. The volume of water received by the 40% SMC plants was three times greater (fall) and 12 times greater (spring) than the 20% SMC plants during greenhouse production and two times greater (fall) and nine time greater (spring) during simulated retail. During production, midday water potentials decreased as the SMC levels decreased, but at the end of the simulated retail, the midday water potentials were the same, suggesting that plants that were drought-stressed during production were acclimated to lower water levels experienced in retail settings. Overall, the 20% SMC treatment produced the best postharvest quality plant resulting from reduced plant height without detrimental effects on flowering. The results demonstrate that while conserving water, controlled irrigation at a lower SMC can produce high-quality plants that have equal shelf life to those that are irrigated at high levels.

Free access

A greenhouse experiment was conducted to evaluate the effects of water stress on leaf water potential, plant growth, and photosynthesis in purple passionflower (Passiflora incarnata). Twenty 4-L pots with two plants in each pot were arranged in a completely randomized design. Ten pots received a daily irrigation dose of 100% evapotranspiration (ET) throughout the 43-day experiment (control). The other 10 pots were subjected to a reduced irrigation (RI) treatment, which was implemented stepwise to achieve a gradual increase in stress, by irrigating them with 50% ET first, then with 25% ET and, finally, with 10% ET. The last stress phase was followed by a recovery phase in which all treatments received the same amount of water (100% ET). A lower water potential was obtained at 10% ET compared with control plants (−2.51 and −0.98 MPa, respectively). Plants in both 25% and 10% ET irrigation treatments had reduced net CO2 assimilation rates (4.25 and 3.50 μmol·m−2·s−1, respectively) than plants watered with 100% ET (8.53 and 6.77 μmol·m−2·s−1, respectively). Values of maximum carboxylation rate allowed by rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase), calculated 31 days after treatment (DAT) application (when RI plants were irrigated with 10% ET) decreased by ≈60%, whereas rate of photosynthetic electron transport and triose phosphate use (TPU) were reduced by ≈30% and ≈45% in the stress treatment compared with the control during the 10% ET irrigation period, respectively. Values of water potential and net CO2 assimilation rates in previously stressed plants were not different from the control treatment in the recovery phase, suggesting that P. incarnata plants could adapt well to landscaping situations where periods of extreme drought can be expected.

Free access

The Texas Pecan Board was established in 1998 to administer the Texas Pecan Checkoff Program and is financed through a half cent per pound assessment on grower pecan sales. The Board spends the assessment collections on a variety of advertising campaigns in an attempt to expand demand for Texas pecans and to increase the welfare of Texas pecan growers. This article presents an evaluation of the economic effectiveness of the Texas Pecan Checkoff Program in expanding sales of Texas pecans. First, the effects of Texas Pecan Board promotion on sales of all Texas pecans are determined using the ordinary least squares estimator followed by a test for differential effects of Texas Pecan Board promotion activities on sales of improved and native Texas pecan varieties using the seemingly unrelated regression estimator. The analysis indicates that the Texas Pecan Checkoff Program has effectively increased sales of improved varieties of Texas pecans but has had no statistically measurable impact on sales of native varieties of Texas pecans. A benefit–cost analysis determines that $35.0 in additional sales revenues are generated for every dollar invested in promotion, indicating that the Texas pecan promotion program has been financially successful. The per unit return is large but on a very few dollars available for investment in promotion implying the need for more investment for more meaningful returns.

Free access

Planting depth during container production may influence plant growth, establishment, and subsequent landscape value. A lack of knowledge about the effects of common transplanting practices may lead to suboptimal performance of planted landscape trees. Planting depth, i.e., location of the root collar relative to soil grade, is of particular concern for posttransplant tree growth both when transplanted to larger containers during production and after transplanting into the landscape. It is unknown whether negative effects of poor planting practices are compounded during the production phases and affect subsequent landscape establishment. This study investigated effects of planting depth during two successive phases of container production (10.8 L and 36.6 L) and eventual landscape establishment using lacebark elm (Ulmus parvifolia Jacq.). Tree growth was greater when planted at grade during the initial container (10.8 L) production phase and was reduced when planted 5 cm below grade. In the second container production phase (36.6 L), trees planted above grade had reduced growth compared with trees planted at grade or below grade. For landscape establishment, transplanting at grade to slightly below or above grade produced trees with greater height on average when compared with planting below grade or substantially above grade, whereas there was no effect on trunk diameter. Correlations between initial growth and final growth in the field suggested that substantial deviations of the original root to shoot transition from at-grade planting was more of a factor in initial establishment of lacebark elm than the up-canning practices associated with planting depth during container production.

Free access

The objective of this study was to assess the changes in leaflet zinc (Zn), leaf nutritional state, vegetative and physiological parameters, and yield quality in pecan trees sprayed with different Zn compounds. Eight-year-old ‘Western Schley’ pecan trees grafted to native seedlings were treated with ZnNO3 (100 mg·L−1 Zn), Zn-EDTA (50, 100, and 150 mg·L−1 Zn), and Zn-DTPA (100 mg·L−1 Zn) and compared with the Zn-untreated control. After 3 years of evaluation, the trees with the best appearance were those treated with ZnNO3 (100 mg·L−1 Zn) and Zn-DTPA (100 mg·L−1 Zn), which showed leaf Zn concentration increases of 73% and 69%, respectively, when compared with the controls. The chlorophyll values of the Zn-treated trees reached 46 SPAD units, equivalent to 43 mg·kg−1 dry weight (DW) of chlorophyll compared with values of 22 mg·kg−1 DW in Zn-deficient leaves. On a leaf area basis, chlorophyll value was 37% lower under Zn deficiency conditions than that of Zn-treated trees. Nut quality was unaffected by the Zn treatments. Data suggest that Zn-DTPA and Zn-NO3 are good options to carry out foliar Zn fertilization in pecan trees.

Free access

Tree transplanting practices influence plant survival, establishment, and subsequent landscape value. However, transplanting practices vary substantially within the horticultural industry. Of particular importance is the location of the root collar relative to soil grade at transplant. The objective of this study was to determine the effects of factorial combinations of planting depths, root collar at grade or 7.6 cm either above or below grade, and soil amendments on container-grown (11 L) Quercus virginiana Mill. Soil treatments included a tilled native soil (heavy clay loam, Zack Series, Zack-urban land complex, fine, montmorillonitic, thermic, udic paleustalfs), native soils amended with 7.6 cm of coarse blasting sand or peat that were then tilled to a depth of 23 cm, or raised beds containing 20 cm of sandy loam soil (Silawa fine sandy loam, siliceous, thermic, ultic haplustalfs). A significant (P ≤ 0.05) block by soil amendment interaction occurred for photosynthetic activity. Incorporation of peat significantly decreased the bulk density of the native soil. Planting depth had no significant effect on photosynthetic activity or stem xylem water potential at 3 months after transplant. Soil water potentials did not statistically differ among treatments.

Free access

Seedlings from 13 open-pollinated families of Taxodium distichum (L.) L.C. Richard from the gulf coast, central and south Texas, and Mexico were grown in a nursery in College Station, Texas. Forty seedlings per family were measured on three dates during the production cycle; 99, 109, and 133 days after sowing in Spring and Summer 2004. A two-step cluster analysis based on height and trunk diameter created 3 clusters of families. Cluster 1 had a mean height of 32 cm and a mean trunk diameter of 3.3 mm. Cluster 2 had a mean height of 33 cm and a mean trunk diameter of 3.4 mm. Cluster 3 had a mean height of 43 cm and a mean trunk diameter of 4.1 mm. Although clusters 1 and 2 are statistically significantly different, practically there is little difference between the two. The families from Mexico and central Texas were all in cluster 1 or 2 and the families collected from the gulf coast were all placed in cluster 3, with the exception of a single family from Biloxi, Miss., which was placed in cluster 1. Analysis of covariance revealed that family membership and days after sowing were both highly significant, as well as an interaction between family and days, for height. Families from Mexico and central and south Texas were 10 to 15 cm shorter than the families from the gulf coast, with the exception of the single family from Biloxi, Miss. Only days and the interaction between family and days were significant for trunk diameter. A pattern similar to the cluster analysis means was seen among the families for trunk diameter in the analysis of covariance.

Free access