Whole plant response of crop and weed species to high subsoil boron

2006 ◽  
Vol 57 (7) ◽  
pp. 761 ◽  
Author(s):  
Eun-Young Choi ◽  
Ann McNeill ◽  
David Coventry ◽  
James Stangoulis

Within the semi-arid region of south-eastern Australia, high levels of subsoil boron (B) in alkaline soil can limit production of dryland crops. The aim of this research was to investigate the whole plant response to a range of subsoil-extractable B concentrations for a number of crop and weed species common to agricultural areas of South Australia. Specifically, the objectives were to determine (a) the morphological response of the entire root system to high subsoil B and (b) the available B concentrations in subsoil critical for expression of shoot traits commonly used in selection of B tolerance. Barley grass (Hordeum glaucum L.), crop barley (Hordeum vulgare) variety Clipper and breeders’ line VB9953, fababean (Vicia faba var. Fjiord), Lincoln weed (Diplotaxis tenuifolia L.), prickly lettuce (Lactuca serriola), and evening primrose (Oenothera stricta L.) were grown in sealed PVC cylinders (500 mm deep by 150 mm diam.) containing a sandy soil. The concentration of extractable B in the topsoil (0–0.20 m), considered non-toxic, was 0.5 mg/kg for all cylinders but a range of B treatments (0.5, 2.4, 4.3, 6.8, or 12.2 mg/kg) was applied directly to the subsoil (0.30–0.50 m). Increasing the concentration of extractable B in the subsoil decreased root dry weight in this region, but did not reduce water use from subsoil by barley grass or evening primrose. The response of the roots in the topsoil and subsequent responses in the shoot also differed among species. Symptoms of B toxicity in shoots of all the species were observed at subsoil-extractable B concentrations of 12.2 mg/kg and at lower concentrations in some of the crop and weed species. Shoot growth, total water use, and root growth in topsoil of Clipper and Lincoln weed were severely impaired by high subsoil-extractable B, as was topsoil root growth in evening primrose, with the reduction in the weed species being mostly associated with a decrease in taproot dry weight. Barley grass, VB9953, evening primrose, and to a lesser extent fababean and prickly lettuce, maintained shoot growth at all subsoil-extractable B concentrations, despite a reduction in subsoil water use by VB9953. Prickly lettuce and VB9953 also sustained root growth in the topsoil whilst fababean and barley grass increased root growth in the topsoil in response to high subsoil extractable B. There was no direct relationship between the quantity of B accumulated in shoots and detrimental effects on growth. Furthermore, there appeared to be no direct relationship between water uptake and B uptake since irrespective of the effect of subsoil B on either subsoil or total water use, shoot B concentration increased in all the species/genotypes as subsoil B increased. The degree to which plants were deemed to exhibit tolerance was, therefore, highly dependent upon the trait used for assessment. One suggestion in the current study is that shoot dry matter in B toxic soil can be a consistent parameter for considering varieties for tolerance to B toxicity.

HortScience ◽  
2018 ◽  
Vol 53 (12) ◽  
pp. 1891-1896 ◽  
Author(s):  
Nastaran Basiri Jahromi ◽  
Amy Fulcher ◽  
Forbes Walker ◽  
James Altland ◽  
Wesley Wright ◽  
...  

Controlling irrigation using timers or manually operated systems is the most common irrigation scheduling method in outdoor container production systems. Improving irrigation efficiency can be achieved by scheduling irrigation based on plant water needs and the appropriate use of sensors rather than relying on periodically adjusting irrigation volume based on perceived water needs. Substrate amendments such as biochar, a carbon (C)-rich by-product of pyrolysis or gasification, can increase the amount of available water and improve irrigation efficiency and plant growth. Previous work examined two on-demand irrigation schedules in controlled indoor (greenhouse) environments. The goal of this study was to evaluate the impact of these on-demand irrigation schedules and hardwood biochar on water use and biomass gain of container-grown Hydrangea paniculata ‘Silver Dollar’ in a typical outdoor nursery production environment. Eighteen independently controlled irrigation zones were designed to test three irrigation schedules on ‘Silver Dollar’ hydrangea grown in pine bark amended with 0% or 25% hardwood biochar. The three irrigation schedules were conventional irrigation and two on-demand schedules, which were based on substrate physical properties or plant physiology. Conventional irrigation delivered 1.8 cm water in one event each day. The scheduling of substrate-based irrigation was based on the soilless substrate moisture characteristic curve, applying water whenever the substrate water content corresponding to a substrate water potential of –10 kPa was reached. The plant-based irrigation schedule was based on a specific substrate moisture content derived from a previously defined relationship between substrate moisture content and photosynthetic rate, maintaining the volumetric water content (VWC) to support photosynthesis at 90% of the maximum predicted photosynthetic rate. Total water use for the substrate-based irrigation was the same as for the conventional system; the plant-based system used significantly less water. However, plant dry weight was 22% and 15% greater, water use efficiency (WUE) was 40% and 40% greater, and total leachate volume was 25% and 30% less for the substrate-based and plant-based irrigation scheduling systems, respectively, than for conventional irrigation. The 25% biochar amendment rate reduced leachate volume per irrigation event, and leaching fraction, but did not affect total water use or plant dry weight. This research demonstrated that on-demand irrigation scheduling that is plant based or substrate based could be an effective approach to increase WUE for container-grown nursery crops without affecting plant growth negatively.


2013 ◽  
Vol 31 (4) ◽  
pp. 259-266 ◽  
Author(s):  
Arjina Shrestha ◽  
Janet C. Cole

Water use, growth, and leaf necrosis of Burkwood viburnum, Korean spice viburnum, and leatherleaf viburnum were evaluated on plants grown in 0 (full sun), 30, or 60% shade during 2010 and 2011. In both years, total water use of Burkwood viburnum decreased with increased shade intensity. Water use of leatherleaf viburnum was lowest in 0% and highest in 30% shade. Daily water use was lower in 0% than in 30 or 60% shade for leatherleaf viburnum plants in August of both years and September of 2010 due to greater leaf necrosis, leaf abscission, and less growth in height and width. In both years, growth in height and width, and leaf number at harvest generally increased in all three species with increased shade intensity. All species had a larger leaf area, stem dry weight, and root dry weight in 30 and 60% than in 0% shade. Shade intensity did not influence root to shoot (R/S) ratio in Burkwood viburnum in 2010, but in 2011, a curvilinear relationship occurred between R/S ratio and shade intensity. Root to shoot ratio of Korean spice and leatherleaf viburnum decreased linearly in 2010 but curvilinearly in 2011 with increasing shade. Leaf necrosis ratings were lower in shaded plants of all three species in both years. Results indicate that greater plant growth, quality, and water use efficiency occurs when these three viburnum species are grown in shade than when they are grown in full sun.


2015 ◽  
Vol 33 (3) ◽  
pp. 137-141
Author(s):  
Bruce R. Roberts ◽  
Chris Wolverton ◽  
Samantha West

The efficacy of treating soilless substrate with a commercial humectant was tested as a means of suppressing drought stress in 4-week-old container-grown Zinnia elegans Jacq. ‘Thumbelina’. The humectant was applied as a substrate amendment at concentrations of 0.0, 0.8, 1.6 and 3.2% by volume prior to withholding irrigation. An untreated, well-watered control was also included. The substrate of treated plants was allowed to dry until the foliage wilted, at which time the plants were harvested and the following measurements taken: number of days to wilt (DTW), xylem water potential (ψx), shoot growth (shoot dry weight, leaf area) and root growth (length, diameter, surface area, volume, dry weight). For drought-stressed plants grown in humectant-treated substrate at concentrations of 1.6 and 3.2%, DTW increased 25 and 33%, respectively. A linear decrease in ψx was observed as the concentration of humectant increased from 0.0 to 3.2%. Linear trends were also noted for both volumetric moisture content (positive) and evapotranspiration (negative) as the concentration of humectant increased. For non-irrigated, untreated plants, stress inhibited shoot growth more than root growth, resulting in a lower root:shoot ratio. For non-irrigated, humectant-treated plants, the length of fine, water-absorbing roots increased linearly as humectant concentration increased from 0.0 to 3.2%. Using humectant-amended substrates may be a management option for mitigating the symptoms of drought stress during the production of container-grown bedding plants such as Z. elegans.


2000 ◽  
Vol 51 (6) ◽  
pp. 701 ◽  
Author(s):  
C. L. Davies ◽  
D. W. Turner ◽  
M. Dracup

We studied the adaptation of narrow-leafed lupin (Lupinus angustifolius) and yellow lupin (L. luteus) to waterlogging because yellow lupin may have potential as a new legume crop for coarse-textured, acidic, waterlogging-prone areas in Western Australia. In a controlled environment, plants were waterlogged for 14 days at 28 or 56 days after sowing (DAS). Plants were more sensitive when waterlogged from 56 to 70 DAS than from 28 to 42 DAS, root growth was more sensitive than shoot growth, and leaf expansion was more sensitive than leaf dry weight accumulation. Waterlogging reduced the growth of narrow-leafed lupin (60–81%) more than that of yellow lupin (25–56%) and the response was more pronounced 2 weeks after waterlogging ceased than at the end of waterlogging. Waterlogging arrested net root growth in narrow-leafed lupin but not in yellow lupin, so that after 2 weeks of recovery the root dry weight of yellow lupin was the same as that of the control plants but in narrow-leafed lupin it was 62% less than the corresponding control plants. Both species produced equal amounts of hypocotyl root when waterlogged from 28 to 42 DAS but yellow lupin produced much greater amounts than narrow-leafed lupin when waterlogged from 56 to 70 DAS.


1992 ◽  
Vol 70 (7) ◽  
pp. 1488-1492 ◽  
Author(s):  
Peter Nosko ◽  
Kenneth A. Kershaw

Week-old white spruce seedlings were grown for 7 days at pH 4.5, 3.9, 3.65, or 3.5 using a continuous flow system to deliver experimental solutions. At each pH, seedlings received either no aluminum or 10 μM Al, a concentration 2 – 3 orders of magnitude lower than the reported minimum Al concentrations required to induce toxicity symptoms in seedlings of a variety of tree species. In – Al treatments, root elongation was reduced at pH 3.9 and root dry weight was reduced at pH 3.5, compared with seedlings grown at pH 4.5. Exposure to 10 μM Al caused further reduction of root growth, the magnitude of which increased as pH decreased. This suggests that seedling root growth was affected by the increased proportion of the total Al existing as phytotoxic Al3+ at lower pH values or by an interaction of Al3+ and H+. Neither pH nor Al affected shoot growth. Both acidity and Al could limit natural regeneration of white spruce by preventing seedling establishment. Key words: aluminum toxicity, soil acidity, forest decline, white spruce, Picea glauca, forest regeneration.


2000 ◽  
Vol 18 (2) ◽  
pp. 66-70 ◽  
Author(s):  
Linda B. Stabler ◽  
Chris A. Martin

Abstract Growth and water use efficiency (WUE) of two, common Southwest landscape plants, red bird of paradise (Caesalpinia pulcherrima L.) and blue palo verde (Cercidium floridum Benth. Ex A. Gray), were studied in response to three irrigation regimens (frequent, moderate, and infrequent) that mimicked a range of residential landscape watering practices in Phoenix, AZ. During 50 to 58 and 138 to 147 days after the start of irrigation treatments (DAT), mid-day measurements of shoot water potential (Ψ), osmotic potential (Ψ0), and gas exchange were made. Concurrently, diurnal measurements of whole plant transpiration (T) and estimates of dry weight accrual were made to calculate WUE. More frequent irrigations increased shoot length of both species and dry weight of Cercidium. For both species, Ψ and Ψ0 showed patterns of osmotic regulation as the substrate dried between watering events for moderately and infrequently irrigated plants. Infrequently irrigated Caesalpinia and Cercidium had the lowest WUE, except for 138 to 147 DAT during which time infrequently irrigated Cercidium had the highest WUE. Instantaneous transpiration efficiency (ITE) was negatively correlated to the ratio of intracellular to ambient CO2 (Ci/Ca) in all treatments, suggesting that under more frequently irrigated conditions, WUE of Caesalpinia and Cercidium might be reduced by negative feedback effects of high Ci/Ca ratios on stomatal conductance.


Weed Science ◽  
1991 ◽  
Vol 39 (1) ◽  
pp. 27-32
Author(s):  
Larry D. Knerr ◽  
Herbert J. Hopen ◽  
Nelson E. Balke

Laboratory studies demonstrated that naptalam safens cucumber against the phytotoxic effects of chloramben. In petri dish studies, cucumber seedlings grown from seeds exposed to chloramben plus naptalam had greater shoot growth, root growth, and dry weight than seedlings grown from seeds exposed to chloramben alone. Naptalam also partially reversed the reduction in dry weight of various plant parts caused by exposure of roots of hydroponically grown seedlings to chloramben. More radioactivity from root-applied14C-chloramben remained in cucumber roots and less was translocated to shoots with a14C-chloramben plus naptalam treatment than with a14C-chloramben alone treatment. Naptalam appeared to influence chloramben metabolism. In various plant parts, concentrations of chloramben and its metabolites differed between the two treatments.


2011 ◽  
Vol 62 (11) ◽  
pp. 972 ◽  
Author(s):  
Qifu Ma ◽  
Richard Bell ◽  
Ross Brennan

In the agricultural lands of south-western Australia, salinity severely affects about 1 million hectares, and there is also widespread occurrence of potassium (K) deficiency. This study investigated whether the effects of sodium (Na) on crop K nutrition vary with plant salt sensitivity. In a glasshouse experiment with loamy sand, two barley cultivars (Hordeum vulgare L. cv. Gairdner, salt sensitive, and cv. CM72, salt tolerant) and one wheat cultivar (Triticum aestivum L. cv. Wyalkatchem, salt tolerant) were first grown in soil containing 30 mg extractable K/kg for 4 weeks to create mildly K-deficient plants, then subjected to Na (as NaCl) and additional K treatments for 3 weeks. Although high Na (300 mg Na/kg) reduced leaf numbers, moderate Na (100 mg Na/kg) hastened leaf development in barley cultivars but not in wheat. In the salt-tolerant CM72, moderate Na also increased tiller numbers, shoot dry weight and Na accumulation, but not root growth. The positive effect of moderate Na on shoot growth in CM72 was similar to that of adding 45 mg K/kg. Root growth relative to shoot growth was enhanced by adequate K supply (75 mg K/kg) compared with K deficiency, but not by Na supply. Soil Na greatly reduced the K/Na and Ca/Na ratios in shoots and roots, while additional K supply increased the K/Na ratio with little effect on the Ca/Na ratio. The study showed that the substitution of K by Na in barley and wheat was influenced not only by plant K status, but by the potential for Na uptake in roots and Na accumulation in shoots, which may play a major role in salt tolerance. The increased growth in shoots but not roots of salt-tolerant CM72 in response to moderate Na and the greater adverse effect of soil K deficiency on roots than shoots in all genotypes would make the low-K plants more vulnerable to saline and water-limited environments.


1996 ◽  
Vol 26 (12) ◽  
pp. 2145-2152 ◽  
Author(s):  
George A. Schier ◽  
Carolyn J. McQuattie

Mycorrhizal colonization and nutrient supply may have important effects on aluminum toxicity in trees grown on acidic, nutrient-poor soils. The interacting effects of mycorrhizal inoculation, nutrient level, and Al treatment on growth and mineral nutrition of pitch pine (Pinusrigida Mill.) seedlings grown with and without the ectomycorrhizal fungus Pisolithustinctorius (Pers.) Coker & Couch were determined. The seedlings were grown for 66 days in sand irrigated with 0.1- or 0.2-strength nutrient solution (pH 3.8) containing 0, 10, or 20 mg/L Al (0, 0.37, or 0.74 mM). Across nutrient and Al levels total dry weight of ectomycorrhizal (ECM) seedlings was 75% greater than that of nonmycorrhizal (NM) seedlings. Doubling the nutrient level increased the dry weight of NM seedlings by 120%, versus 60% for ECM seedlings. Aluminum reduced root and shoot growth in NM seedlings, but had no effect on shoot growth and only a marginally significant effect on root growth of ECM seedlings. Shoot growth of NM seedlings was more sensitive to Al than root growth. Increased growth of NM seedlings by doubling the nutrient level was least at the highest Al level. Symptoms of Al toxicity in roots (dark, stunted tips) occurred at a lower Al level in NM than ECM seedlings. A strong relationship was not found between Al toxicity and concentrations of Mg and Ca in roots and needles. Enhancement of growth resulting from increased uptake of nutrients due to mycorrhizal inoculation (and) or an increased level of nutrients was the overriding factor affecting the response of pitch pine seedlings to Al.


1987 ◽  
Vol 5 (4) ◽  
pp. 155-158 ◽  
Author(s):  
Stephen C. Blessing ◽  
Michael N. Dana

Juniperus chinensis (L.) ‘Sea Green’ from 3.8 1 (#.1) containers (CG) and comparably sized field grown plants balled and burlapped (B&B) were planted in clay and loam soil in mid-June. Prior to transplanting, root balls of the CG plants were either mechanlcally disrupted by vertical cuts (D/CG) or left undisturbed (CG). Root growth beyond the original root ball and shoot extension growth in loam soil were determined at 8 and 12 weeks, while similar data were collected from loam and clay soils at 16 wks. B&B plants and D/CG plants produced greater dry weight of new roots, but less shoot growth at 8 wks than CG plants with an undisturbed root ball. By 16 wks, B&B plants had produced greater new root dry weight than either CG treatment and shoot growth was not different among treatments. In clay soil B&B plants produced greater dry weight of new roots than CG plants. Root ball disruption reduced new root growth in the heavy soil compared to CG plants. Shoot growth was not different among treatments in the heavy soil, but was significantly diminished compared to shoot growth on the lighter, loam soil.


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