Boron tolerance in annual medics (Medicago spp.)

2012 ◽  
Vol 63 (9) ◽  
pp. 886 ◽  
Author(s):  
J. H. Howie
Keyword(s):  
Rating System ◽  
Boron Toxicity ◽  
Alkaline Soils ◽  
Boron Tolerance ◽  
Wide Range ◽  
Commercial Cultivars ◽  
Leaf Necrosis ◽  
Annual Medics ◽  
Leaf Symptoms ◽  
Pasture Legume

Boron (B) is present at toxic levels in the subsoils of much of the semiarid south-eastern Australian cereal-livestock zone. Boron toxicity is typically associated with alkaline soils, where annual medics (Medicago spp.) are generally the best-adapted pasture legume. New medic cultivars have been developed for which there is no published B tolerance information. Five species of annual medic represented by 13 cultivars were grown in soil amended with B and evaluated for B tolerance. A rating system based on expression of symptoms was modified from earlier research. There was a wide range of response to B, both between and within species. Cultivars varied widely in their expression of symptoms; from showing no or few leaf symptoms (tolerant) to significant leaf necrosis (very sensitive). An integrated summary of both published and previously, unpubl. data for these and other medics is presented to provide a comprehensive and up-to-date comparison between different species and most commercial cultivars. This information will be useful for plant breeders, agronomists and farmers who manage soils with high B levels.

Effect of cultivar on uptake of cadmium by potato tubers

1994 ◽  
Vol 45 (7) ◽  
pp. 1483 ◽  
Author(s):  
MJ McLaughlin ◽  
CMJ Williams ◽  
A McKay ◽  
R Kirkham ◽  
J Gunton ◽  
...  
Keyword(s):  
Dominant Role ◽  
Potato Tubers ◽  
Fresh Weight ◽  
Site Factors ◽  
Cd Accumulation ◽  
Breeding Lines ◽  
Commercial Potato ◽  
Wide Range ◽  
Commercial Cultivars ◽  
Joint Regression Analysis

Cadmium (Cd) accumulation in tubers by commercial potato cultivars was assessed at 12 sites around Australia having differing soil and environmental conditions. At all but two sites there were significant differences in tuber Cd concentrations between cultivars. Some major commercial cultivars had tuber Cd concentrations only half that of others. Advanced breeding lines showed further potential to reduce Cd accumulation. Mean tuber Cd concentrations of the 14 most common cultivars, averaged across all sites, ranged from 30 to 50 8g kg-1 fresh weight (FW), below the maximum permitted concentration (MPC) of 50 8g kg-1 of Cd (FW). However, at some sites certain cultivars exceeded the MPC. A modified joint regression analysis of the data indicated that no cultivars have consistently low or consistently high tuber Cd concentrations across a range of environments. While differences between cultivars were significant, the range in Cd concentrations found between sites was generally greater than the range in Cd concentrations between cultivars at any one site. Thus soil and other site factors (e.g. irrigation water quality, climate, etc.) play a dominant role in controlling Cd accumulation by current commercial cultivars and there is a need to breed new cultivars resistant to Cd accumulation under a wide range of environments.

Grapevine yellow speckle — a newly recognized graft-transmissible disease of Vitis

1972 ◽  
Vol 23 (3) ◽  
pp. 447 ◽  
Author(s):  
RH Taylor ◽  
RC Woodham
Keyword(s):  
Seed Transmission ◽  
Ringspot Virus ◽  
Herbaceous Plants ◽  
Grapevine Fanleaf Virus ◽  
The Past ◽  
Tomato Ringspot Virus ◽  
Wide Range ◽  
Heat Therapy ◽  
Transmissible Disease ◽  
Leaf Symptoms

Evidence is presented to show that many grapevines showing leaf symptoms which, particularly when intense, cannot be distinguished from those caused by strains of grapevine fanleaf virus (GFV) or tomato ringspot virus (TRSV) are infected with a previously undescribed disease for which the name grapevine yellow speckle (GYS) is proposed. The causal agent of the disease has not been isolated, but it is graft-transmissible from infected to healthy grapevines. It has not been transmitted by sap inoculation to herbaceous plants. The disease has been detected in some grapevine cultivars grown in Australia for many years, and also in several other cultivars and rootstocks imported from California over the past 10 years. There is no evidence of natural spread or of seed transmission. Attempts to eliminate GYS from plants by heat therapy and propagation of tip cuttings have been unsuccessful. Mataro and LN33, the best indicators for GYS at present, are not entirely satisfactory and there is a need to find an indicator which will detect GYS in a wide range of environments. The disease has not been previously detected, probably because of its similarity to GFV and TRSV and its peculiarity in expressing symptoms only in some environments.

Patterns of seed softening and seedling emergence of nineteen annual medics during three years after a single seed crop in southern Queensland

1997 ◽  
Vol 37 (7) ◽  
pp. 767 ◽  
Author(s):  
D. L. Lloyd ◽  
G. B. Taylor ◽  
B. Johnson ◽  
K. C. Teasdale
Keyword(s):  
Seedling Emergence ◽  
Soil Surface ◽  
Farming Systems ◽  
The Other ◽  
Research Station ◽  
Hard Seed ◽  
Diurnal Cycles ◽  
Wide Range ◽  
Burr Medic ◽  
Annual Medics

Summary. To produce seed to determine the rates of seed softening of annual medics in the subtropics, 8 lines of barrel medic (Medicago truncatula), 3 lines of burr medic (M. polymorpha), 4 lines of snail medic (M. scutellata), and 1 line of each of button medic (M. orbicularis), strand medic (M. littoralis) and gama medic (M. rugosa) were grown at Warra in southern inland Queensland, in 1993. Seed of a fourth line of burr medic, a naturalised line, was harvested from Hermitage Research Station at that time. Pods were placed on the soil surface and buried at a depth of 7 cm, both in flywire envelopes and as free pods. Residual hard seed numbers were determined each year for 3 years from the envelopes, and seedlings were counted and removed from the free pods after each germination event. Patterns of softening of seeds from the same seed populations were also determined after placing them in a laboratory oven with a diurnal temperature fluctuation of 60/15° C for periods of 16, 40 and 64 weeks followed, after each time period, by 4 diurnal cycles of 35/10°C. More than 90% of the original seeds were hard. Seed softening at the soil surface ranged from 26% after 3 years in button medic to almost complete softening in the gama medic after only 2 years. Burial had little effect on the rate of softening of the button medic but about halved the rate of softening of the other lines. The barrel medics were vulnerable to losses of large numbers of seedlings which softened and germinated in January–February and the snail medics from seedlings emerging in August–December. The proportion of soft seeds recovered as seedlings in the buried compared with the surface pods was higher in the larger-seeded medics, snail and gama, and lower in the other, smaller-seeded medics. Laboratory techniques effectively ranked the medic lines for their rate of seed softening in the field and provided some insight into their seasonal patterns of seed softening. A wide range of seed softening patterns is available for fitting the requirements of various farming systems. The most appropriate pattern of softening will depend on the variability of medic seed production between years and the need for self regeneration of the medic after a cereal crop.

Effects of boron toxicity on root and leaf anatomy in two Citrus species differing in boron tolerance

Trees ◽  
2014 ◽  
Vol 28 (6) ◽  
pp. 1653-1666 ◽  
Author(s):  
Jing-Hao Huang ◽  
Zi-Jian Cai ◽  
Shou-Xing Wen ◽  
Peng Guo ◽  
Xin Ye ◽  
...  
Keyword(s):  
Leaf Anatomy ◽  
Boron Toxicity ◽  
Citrus Species ◽  
Boron Tolerance ◽  
Root And Leaf Anatomy

scholarly journals Developing a comprehensive Drift Reduction Technology risk assessment scheme

2014 ◽  
Vol 54 (1) ◽  
pp. 85-89 ◽  
Author(s):  
J. Connor Ferguson ◽  
Andrew J. Hewitt ◽  
John A. Eastin ◽  
Robert J. Connell ◽  
Rory L. Roten ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Risk Reduction ◽  
Environmental Stewardship ◽  
Rating System ◽  
Spray Drift ◽  
Spray Application ◽  
Reduction Scheme ◽  
Exposure Risk ◽  
Rating Systems ◽  
Wide Range

Abstract Drift Reduction Technologies (DRTs) are becoming increasingly important for improving spray applications in many countries including New Zealand (NZ). Although there is a growing database on the performance of DRTs, there is no rating system showing the effectiveness of the DRT’s performance. In Europe, DRTs are classified relative to current reference technologies as part of the rating systems used to establish spray drift risk reduction. We have recommended some key elements of such a comprehensive exposure risk reduction scheme for any country, based on prior and on-going research into the performance of specific DRTs in row, tree, and vine crops. Our intention was to create a rating system to determine the effectiveness of a given technology. This rating system would improve spray application practices and environmental stewardship for a wide range of crops and application scenarios.

The effect of solution pH and external calcium concentration on the early growth and nodulation of several annual Medicago species

1990 ◽  
Vol 41 (5) ◽  
pp. 933 ◽  
Author(s):  
MA Ewing ◽  
AD Robson
Keyword(s):  
Calcium Concentration ◽  
Acid Soils ◽  
Early Growth ◽  
Low Ph ◽  
Solution Ph ◽  
Nodule Number ◽  
Low Calcium ◽  
Wide Range ◽  
Effects Of Ph ◽  
Annual Medics

The study tested the hypothesis that annual medic species which nodulate well in acid soils in the field (M. murex Willd. and M. polymorpha L.) will nodulate better in acid solutions with low calcium concentrations than annual medics which nodulate poorly in acid soils (M, truncatula Gaertn.). Effects of pH (5.5 and 6.5) and calcium concentration (0.2, 0.5, 1 and 2 mM) on the early growth and nodulation of three annual medic species (M. truncatula, M. polymorpha and M. murex) were investigated. Increasing pH or calcium concentration did not increase plant growth for any of the species. However, nodulation was generally depressed by low pH for all species. Increasing calcium concentration in solution increased nodulation in all species. Effects of low pH and low calcium concentration in decreasing nodule number were much greater for M. truncatula than for M. polymorpha and M. murex. At pH 5.5, M. truncatula failed to nodulate at any calcium concentration, whereas a large proportion of M. murex plants nodulated at 1 mM calcium and some M. polymorpha plants nodulated at 2 mM calcium. At pH 6.5, M. polymorpha required 1 mM calcium in solution for maximum nodule number, and M. murex only 0.5 mM calcium, whereas nodule number for M. truncatula increased up to 2 mM calcium, the highest concentration used. The results provide the basis for a simple screening system to distinguish differences among annual medics in nodulation tolerance to acidity. The maintenance of ranking among species with respect to nodulation over a wide range of stresses induced by combinations of low pH and calcium concentration suggest that screening using a single stress combining these two components would be adequate. Nodulation differences between species can be simply and effectively assessed using a scoring system combining number size and location of nodules.

The root morphology of Lupinus angustifolius in relation to other Lupinus species

1993 ◽  
Vol 44 (6) ◽  
pp. 1367 ◽  
Author(s):  
JC Clements ◽  
PF White ◽  
BJ Buirchell
Keyword(s):  
Root System ◽  
Lateral Roots ◽  
Poor Performance ◽  
Alkaline Soils ◽  
Poor Growth ◽  
Wide Range ◽  
Proteoid Root ◽  
Primary Lateral ◽  
Secondary Roots ◽  
Coarse Soil

Commercial L. angustifolius cultivation is restricted to acid to neutral coarse-textured soils in Australia. An unsuitable root system may be part of the reason for the poor performance on fine-textured or alkaline soils. As a first step to examine this question plants of 12 annual Lupinus species were grown in a coarse soil with the aim of describing the range of root morphologies within the genus and to compare these to commercial L. angustifolius. A wide range of rooting patterns were observed. The differences in the dominance of the taproot was pronounced between species. The commercial genotype of L. angustifolius occupied an extreme within the range of root morphologies of the species. Roots of L. angustifolius consisted of a dominant taproot and a relatively high number of primary lateral roots but few secondary roots. In contrast, the primary, secondary and tertiary lateral roots of L. pilosus, L. mutabilis, L. atlanticus, L. palaestinus and L. micranthus were more dominant than the taproot. The length and distribution of primary lateral roots along the taproot also varied between species. The number of primary lateral roots fell rapidly with depth in L. angustifolius and L. mutabilis, while the other species had a more even distribution. L. angustifolius had a less extensive root system and relatively thick roots when compared to species such as L. albus and L. mutabilis. L. luteus also had relatively thick roots. The relatively thick roots and less extensive lateral root system in commercial L. angustifolius may partially explain its poor growth on fine-textured soils, where a greater proliferation of finer, lateral roots may be necessary. Proteoid root formation was observed for L. albus, L. cosentinii, L. pilosus, L. palaestinus, L. micranthus, L. digitatus, L. princei and L. atlanticus. They were particularly numerous in L. micranthus and L. albus. The structure of proteoid root clusters varied between species.

Virus diseases of annual pasture legumes: incidences, losses, epidemiology, and management

2012 ◽  
Vol 63 (5) ◽  
pp. 399 ◽  
Author(s):  
Roger A. C. Jones
Keyword(s):  
Large Scale ◽  
Current Knowledge ◽  
Subterranean Clover ◽  
Summer Rainfall ◽  
Virus Diseases ◽  
Pasture Legumes ◽  
Improvement Programs ◽  
Annual Medics ◽  
Grazed Swards ◽  
Pasture Legume

This paper reviews current knowledge concerning the occurrence, losses caused, epidemiology, and management of virus diseases of annual pasture legumes. The viruses commonly present are spread by contact, or aphid vectors either non-persistently or persistently. Whether they are seed-borne and their means of transmission are critical factors determining their incidences within pastures in climatic zones with dry summers or substantial summer rainfall. Large-scale national or state surveys of subterranean clover pastures revealed that some viruses reach high infection incidences. Contamination with seed-borne viruses was widespread in plots belonging to annual pasture legume improvement programs and seed stocks of subterranean clover, annual medics, and alternative annual pasture legumes, and in commercial annual medic seed stocks. Yield loss studies with grazed swards were completed for three common viruses: two in subterranean clover and one in annual medics. These studies demonstrated considerable virus-induced losses in herbage and seed yields, and established that virus infection causes deteriorated pastures with high weed contents even when foliar symptoms are mild. Comprehensive integrated disease management tactics involving phytosanitary, cultural, chemical, or host resistance measures were devised for these three viruses in infected pastures, and for seed-borne viruses in annual pasture legume improvement programs. Several other viruses are potentially important, but, with these, quantification of losses caused in grazed swards is lacking and information on incidences in pastures is currently insufficient. Critical research and development gaps that need addressing are identified.

Estimating nitrous oxide emissions from flood-irrigated alkaline grey clays

Soil Research ◽  
2003 ◽  
Vol 41 (2) ◽  
pp. 197 ◽  
Author(s):  
Ian J. Rochester
Keyword(s):  
Nitrous Oxide ◽  
Mole Fraction ◽  
Management Strategies ◽  
Acid Soils ◽  
Nitrous Oxide Emissions ◽  
N2o Emissions ◽  
15N Balance ◽  
Alkaline Soils ◽  
Negative Exponential Function ◽  
Wide Range

Concern has mounted over recent decades regarding the emission of nitrous oxide (N2O) to the atmosphere through human activities. Modern agriculture has contributed to this with elevated use of nitrogenous fertilizers and irrigation. Irrigated cotton grown on alkaline heavy clay soils often uses nitrogen fertiliser inefficiently, due largely to N loss (commonly 50–100 kg N/ha) through denitrification. However, the amount of denitrified N emitted as N2O has rarely been measured. This paper derives estimates of the quantities of N2O emitted from N fertiliser applied to alkaline grey clays.A negative exponential function between the N2O/N2 mole fraction and soil pH was derived from a search of laboratory and field studies published by numerous authors using a wide range of soil types. A greater proportion of N2O relative to N2 is emitted from acid soils; approximately equivalent amounts of each gas are emitted from soil of pH 6.0. For the alkaline grey clays (pH 8.3–8.5), the N2O/N2 mole fraction was about 0.024.The quantities of N2O emitted from alkaline grey clays during the growth of a cotton crop were estimated by applying this relationship to 15N balance studies where N fertiliser losses had been measured. Using this approach, about 2 kg N/ha (~1.1% of the N applied) was calculated to be lost as N2O during the cotton-growing season. This is similar to the value of 1.25% commonly used to estimate N2O emissions from N fertiliser, but this estimation should only be applied to alkaline soils; a larger percentage of the fertiliser N denitrified from acid soils should be emitted as N2O-N. These estimates of N2O emissions require validation with field experimentation.The low (negligible) values for N2O emission from flooded fields compared with laboratory observations are discussed. It is possible that high N2O emissions observed under laboratory conditions result from the shallow depth of soil, reducing the opportunity for N2O to be further reduced as it diffuses through the soil profile. Management strategies that have the potential to reduce N2O emissions are discussed.

scholarly journals Landscape Performance of Buck Roses under Minimal-input Conditions in North-central Texas

2020 ◽  
Vol 30 (2) ◽  
pp. 231-237
Author(s):  
Derald Harp ◽  
Gaye Hammond ◽  
David C. Zlesak ◽  
Greg Church ◽  
Mark Chamblee ◽  
...  
Keyword(s):  
Black Spot ◽  
State University ◽  
Alkaline Soils ◽  
North Central ◽  
Diplocarpon Rosae ◽  
Landscape Performance ◽  
Wide Range ◽  
North Central Texas ◽  
Central Texas ◽  
Dead Plant

Griffith Buck (Iowa State University) bred roses (Rosa sp.) to survive long, cold winters and hot, humid summers yet still retain their foliage without fungicides. Unfortunately, there is little known about the performance of Buck roses in the southern United States. Thirty-eight Buck rose cultivars were evaluated for flowering, disease resistance, drought tolerance, and overall landscape performance in alkaline soils with no fertilizer, no pesticides, and only limited irrigation. Flowering occurred on a bimodal basis, with the highest per plant mean bloom number (16.3 blooms) and bloom coverage (9.7%) in April, and a second flowering in the fall, with 13.7 blooms per plant and 6.9% bloom coverage in October. Drought stress symptoms were most evident in October, with a wide range of symptom severity across cultivars. Black spot (Diplocarpon rosae) and powdery mildew (Podosphaera pannosa) incidence were rare across all roses and years. Landscape performance scores, rated using a 0 to 10 scale with 10 representing a perfect plant and 0 a dead plant, were highest in April (6.5) and lowest in June (4.6) and July (4.6). Landscape performance was not correlated with bloom number or coverage. While unable to recommend many of the Buck roses for north-central Texas, the cultivars April Moon and Freckles, and possibly a few other roses, can join Carefree Beauty™ (BUCbi) as recommended roses for the area.

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