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  • Author or Editor: Thayne Montague x
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Water quality and quantity are critical issues in the Southwest United States and many other locations in the world. Use of reclaimed water for landscape irrigation can conserve potable water significantly and possibly reduce fertilizer application. A potential concern of using alternative water sources is elevated salt levels, which can have adverse effects on plant growth and aesthetic appearance. Most Texas native wildflowers are known to be hardy and easy to maintain, and are drought tolerant after establishment. In addition, native wildflowers provide wildlife habitat and support native pollinators. However, little information is available on salinity tolerance of many Texas native wildflower species. In this study, two separate hydroponic experiments were conducted to determine salt tolerance of three Texas native wildflower species: Gaura villosa Torr. (wooly gaura), Xanthisma texanum DC. (Texas sleepy daisy), and Ipomopsis rubra (L.) Wherry (standing cypress). Species were suspended in a hydroponic setting using a randomized complete block design with a control [municipal reverse-osmosis (RO) water with a nutrition solution at an electrical conductivity (EC) of 3.0 dS·m–1] and three salinity treatments: 5.0, 7.0, and 11.0 dS·m–1 EC. Sixty days after salinity treatments were initiated, percent survival, visual rating, fresh weight, and length measurements were recorded on root and shoot tissue. To determine tissue percentage sodium (Na+), calcium (Ca2+), and chloride (Cl), shoot and root tissues were dried and ground for tissue analysis. At the end of each experiment, total percent survival for X. texanum, G. villosa, and I. rubra were 100%, 94%, and 76%, respectively, with the greatest mortality rate at the highest salinity treatment. Shoot dry weight and plant growth index (PGI) decreased in all three species as salinity of irrigation water increased. Visual qualities of all species were mainly compromised at the highest salinity level. Ion concentrations in root and shoot tissues were affected by salinity levels and varied among species. Different mechanisms of salt tolerance (ion exclusion, salt excretion, and tissue tolerance to high concentrations of Na+ or Cl) have been observed among wildflower species, and results indicate different salt tolerance mechanisms were exhibited by each trial species. In addition, results indicate I. rubra can be identified as moderately salt tolerant (EC up to 7.0 dS·m–1), whereas, X. texanum and G. villosa can be classified as salt tolerant (EC up to 11.0 dS·m–1). Results from this study suggest great potential of these native Texas wildflowers in landscapes using limited-quality irrigation water or landscapes with soil salinity concerns.

Open Access

Gas exchange and growth of transplanted and non-transplanted Acer platanoides `Schwedleri' and Tilia cordata `Greenspire' trees were investigated. This study was conducted on trees planted in 1991 in a field nursery near Logan, Utah. In Spring 1995, three trees of each species were moved with a tree spade to a new location within the nursery and three non-transplanted trees were selected as controls. To simulate landscape conditions, all trees were watered at the time of planting and once per week during the growing season. Pre-dawn water potential, dawn-to-dusk stomatal conductance, mid-day photosynthesis, and growth data were collected over a 2-year period. Transplanted trees of each species were under more water stress (indicated by more negative pre-dawn water potential) than non-transplanted trees. However, pre-dawn water potential of transplanted A. platanoides recovered to near non-transplanted levels, while transplanted T. cordata did not. Dawn-to-dusk studies in 1995 and 1996 showed that stomatal conductance was lower throughout the day in transplanted trees. Once again, transplanted A. platanoides recovered to near non-transplanted levels, while transplanted T. cordata did not. A similar trend for mid-day photosynthesis was found for both species in 1995 and 1996. Transplanted trees of each species had less stem area increase, shoot elongation, and total leaf area than non-transplanted trees for each year. These data indicate that transplanted A. platanoides can recover to near non-transplant pre-dawn water potential and gas exchange levels earlier, and therefore establish faster, than transplanted T. cordata. However, after 2 years neither transplanted tree species were able to fully recover to non-transplanted growth rates.

Free access

A survey instrument was designed to determine public opinion on water conservation, water conserving landscapes, the use of native plants in landscapes, home irrigation systems, and the performance of five Texas native plant species [pink evening primrose (Oenothera speciosa); prairie verbena (Verbena bipinnatifida); red yucca (Hesperaloe parviflora); ceniza (Leucophyllum frutescens); and ruellia (Ruellia nudiflora)] grown in low water use landscapes in the semiarid Southwestern United States. On six occasions during the 1999 growing season, participants viewed landscapes and participated in a survey. Survey data indicate that over 90% of respondents thought water conservation was important to the state of Texas. A majority of participants however, believed water conserving landscapes to be expensive to maintain and not aesthetically pleasing. The survey revealed 79% of participants would use native plants if native plants conserved water, and 86% of participants would use native plants if native plants were attractive. Chi-square approximations revealed participant's opinions regarding water conservation and home irrigation systems were influenced by education level and amount of time they participated in weekly horticulture activities. In an open-ended question, participants indicated flowers and healthy leaves were characteristics indicating a plant was performing well. Throughout the year, species in flower received higher ratings than nonflowering species.

Full access

Methoxypyrazines (MPs) are fruit-derived extractable compounds that contribute to cultivar-specific aroma traits in wine, and greater concentrations can contribute to unpleasant vegetative aromas. Both light exposure and temperature have been reported to influence MP content in developing wine grapes, but individual effects of light and temperature are confounded. A novel method of manipulating light exposure with light-emitting diodes (LEDs) was used to impose light treatments with little or no effect on cluster temperature. Three treatments were imposed on developing fruit of Vitis vinifera (cv. Cabernet Sauvignon): 1) clusters exposed to direct sunlight, 2) clusters shaded by the grapevine canopy, and 3) clusters shaded by the canopy and exposed to supplemental LED light. Experiments were conducted over 3 years across pre- and postveraison periods of fruit development. A second experiment imposed the same light exposure treatments to ripening clusters on vines experiencing continual shoot growth during the postveraison period. Light exposure reduced 3-isobutyl-2-methoxypyrazine (IBMP) concentration of developing grape berries in the preveraison period independently of berry heating from solar radiation. Berry IBMP responded less to postveraison light levels, except on vines with active shoot growth, suggesting IBMP synthesis was continued during active vine growth but was suppressed by light. An inverse relationship of growing degree days (GDDs) with berry IBMP was observed, indicating high temperatures also reduce berry IBMP concentration. Response to temperature could result from either radiant heating of light-exposed clusters or from high ambient air temperature. Canopy management should consider the impact of both light and temperature on IBMP, and vine management practices should be adjusted appropriately to regional growing conditions and grape cultivars.

Free access

Demand for locally produced, organically grown leafy greens is increasing throughout the United States. However, due to lack of efficient organic fertilizers (OFs) for soilless substrates, organic greenhouse production of leafy greens may be challenging. Therefore, a greenhouse study was conducted to analyze the effects of six liquid OFs on growth and development of lettuce in a soilless system. Two experiments were conducted using a randomized block design, and treatments included six fish- or plant-based OFs: OF1 (5N–1P–1K), OF2 (2N–5P–1K), OF3 (3N–1P–1K), OF4 (2N–2P–2K), OF5 (4N–1P–1K), and OF6 (3N–3P–2K); one inorganic fertilizer treatment (IF, 24N–8P–16K); and one unfertilized control treatment. Fertilizer solutions were prepared at 2 dS⋅m–1 and applied at 100 mL/plant. In Expt. 1, fresh biomass for IF-treated plants was 12% to 38% greater than OF treatments, whereas this difference ranged from 25% to 57% in Expt. 2. Similarly, leaf area values of IF-treated plants were 5% to 40% greater than OF treatments in Expt. 1, and the difference ranged from 28% to 90% in Expt. 2. A possible explanation could be greater availability of nutrients in the IF treatment compared with OF treatments. There was no significant difference among fertilized treatments for number of leaves and stem diameter. Based on the index-based ranking, fish-based (OF1) and fish- and plant-based (OF2 and OF6) performed well among different liquid OFs used in the study. Although the yield under OFs was less compared with that under IF, there is potential to reduce this yield gap by optimized fertility management of these fertilizers. Future research is needed to investigate the impact of optimized rate, timing, different placement, and additional nitrogen (N) sources of OFs on the soilless production of lettuce.

Open Access

Field experiments were conducted at the Central Texas Olive Ranch in Walburg, TX, in 2011 and 2012 to evaluate the efficacy of mulch and/or preemergence herbicides for weed control in high-density olive (Olea europaea L.) production during orchard establishment. Treatments were initiated on 1 Apr. 2011 and 28 Mar. 2012 and consisted of a nontreated control, isoxaben (2.2 kg a.i./ha), oryzalin (4.5 kg a.i./ha), oxadiazon (3.36 kg a.i./ha), and mesotrione (0.14 kg a.i./ha). Hardwood mulch was applied to half of each plot following herbicide application. Weed counts, combined across species (camphorweed, texas croton, lanceleaf sage, pinnate tansymustard, tumble pigweed, common purslane, and prostrate spurge), were conducted to assess % weed cover at 4 and 12 weeks after treatment (WAT). In 2011, compared with the nonmulched no herbicide treatment, adding mulch reduced weed counts by 23 and increased weed control by 70% 4 WAT. All preemergence herbicide treatments, regardless of mulching regime, resulted in ≥97% weed control 4 WAT with the exception of oryzalin without mulch (91% weed control, 3 weeds/plot). In 2012, compared with the nonmulched no herbicide treatment, adding mulch reduced weed counts by 35 and increased weed control by 64% 4 WAT. Mulching in combination with mesotrione resulted in 100% weed control, significantly greater than mesotrione applied without mulch (98%, 2 weeds/plot) 4 WAT. Oryzalin without mulch resulted in greater weed control (94%, 4 weeds/plot) in 2012 4 WAT; however, this treatment provided the least amount of weed control of all preemergence herbicides tested. By 12 WAT, weed counts were reduced by 21 and 22 in 2011 and 2012, respectively, in response to mulching in the nontreated plots resulting in a 52% and 42% increase in weed control in 2011 and 2012, respectively. Mesotrione was the only treatment affected by mulching regime 12 WAT in 2011 and 2012. Mesotrione in combination with mulch resulted in 100% weed control in 2011 and 2012, while mesotrione without mulch resulted in 93% weed control (3 and 4 weeds/plot) 12 WAT in 2011 and 2012, respectively. Although not statistically significant, isoxaben applied alone in 2011 resulted in 97% weed control (1 weed/plot), while isoxaben in combination with mulch resulted in 94% weed control (3 weeds/plot) 12 WAT. In 2011, oryzalin and oxadiazon resulted in 87% to 92% control, regardless of mulching regime 12 WAT. Weed control in response to isoxaben in 2012 was 95% 12 WAT, regardless of mulching regime. The combination of oxadiazon + mulch resulted in similar weed control (95%, 3 weeds/plot) 12 WAT; however, oxadiazon alone and oryzalin with and without mulch resulted in 87% to 89% weed control. All preemergence herbicides evaluated provided good to excellent weed control. Isoxaben and oryzalin are labeled for use on nonbearing fruit trees or during orchard establishment, while oxadiazon is only labeled for woody ornamentals. Although not labeled for use in orchards, mesotrione may be an alternative for use in olive production. The addition of mulching did not increase weed control except when used in conjunction with mesotrione. Mulch alone provided moderate weed control when preemergence herbicides were not applied. Furthermore, the utilization of mulch in combination with preemergence herbicides may help reduce photodegradation and/or volatilization when irrigation/rainfall is limited.

Free access

This study was conducted to determine the influence of production methods on the growth of container grown flowering dogwood (Cornus florida). The production practices were: full sun, 40% white shade cloth, 40% black shade cloth, and pot-in-pot. The cultivars studied were: cv. `Welch's Junior Miss', cv. `Barton's White', cv. `Weaver's White', and cv. `Welch's Bay Beauty'. The one variety used was pink. Height and caliper data was collected. Plants grown under white shade cloth had the highest overall height and caliper growth, followed by black shade cloth, full sun, and the pot-in-pot production method. The cultivar `Weaver's White' had the highest overall height and caliper growth and the variety pink had the least, regardless of treatment. The remaining cultivars had similar growth regardless of treatment.

Free access