INFLUENCE OF SOIL PHYSICAL CONDITIONS ON ROOT DEVELOPMENT AND ON PRODUCTIVITY OF CITRUS TREES

Soil Science ◽  
1966 ◽  
Vol 102 (2) ◽  
pp. 82-84 ◽  
Author(s):  
J. PATT ◽  
D. CARMELI ◽  
I. ZAFRIR
Keyword(s):  
Root Development ◽  
Physical Conditions ◽  
Citrus Trees

scholarly journals Effect of Various Irrigation Rates on Growth and Root Development of Young Citrus Trees in High-Density Planting

Plants ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1462
Author(s):  
Said A. Hamido ◽  
Kelly T. Morgan
Keyword(s):  
Leaf Area ◽  
Tree Growth ◽  
Root Development ◽  
Root Length ◽  
Planting Density ◽  
Citrus Tree ◽  
Irrigation Rate ◽  
Root Lifespan ◽  
Canopy Volume ◽  
Citrus Trees

Citrus yields have declined by almost 56% since Huanglongbing (HLB) was first found in Florida (2005). That reduction forced citrus growers to replant trees at much higher densities to counter-balance tree loss. The current project aims to determine how much water is required to grow citrus trees at higher planting densities without reducing their productivity. The study was initiated in November 2017 on eight-month-old sweet orange (Citrus sinensis) trees grafted on the ‘US-897′ (Cleopatra mandarin × Flying Dragon trifoliate orange) citrus rootstock planted in the University of Florida, Southwest Florida Research and Education Center (SWFREC) demonstration grove, in Immokalee, FL (lat. 26.42° N, long. 81.42° W). The soil in the grove is Immokalee fine sand (Sandy, siliceous, hyperthermic Arenic Alaquods). The demonstration grove included three densities on two rows of beds (447, 598, and 745 trees per ha) replicated four times each and three densities of three rows of beds (512, 717, 897 trees per ha) replicated six times. Each density treatment was irrigated at one of two irrigation rates (62% or 100%) during the first 15 months (2017–2019) then adjusted (2019–2020) to represent 26.5, 40.5, 53, and 81% based on recommended young citrus trees evapotranspiration (ETc). Tree growth measurements including trunk diameter, height, canopy volume, leaf area, and root development were evaluated. During the first year, reducing the irrigation rate from 100% to 62% ETc did not significantly reduce the young citrus tree growth. Conversely, the lower irrigation rate (62% ETc) had increased citrus tree’s leaf area, canopy volume and tree heights, root lifespan, and root length by 4, 9, 1, 2, and 24% compared with the higher irrigation rate (100%), respectively. Furthermore, the root lifespan was promoted by increasing planting density. For instance, the average root lifespan increased by 12% when planting density increased from 447 to 897 trees per ha, indicating that planting young trees much closer to each other enhanced the root’s longevity. However, when treatments were adjusted from April 2019 through June 2020, results changed. Increasing the irrigation rate from 26.5% to 81% ETc significantly enhanced the young citrus tree growth by increasing citrus tree’s canopy volume (four fold), tree heights (29%), root lifespan (86%), and root length (two fold), respectively. Thus, the application of 81% ETc irrigation rate in commercial citrus groves is more efficient for trees from two to four years of age.

The effect of soil physical conditions produced by various cultivation systems on the root development of winter wheat

1973 ◽  
Vol 80 (3) ◽  
pp. 435-443 ◽  
Author(s):  
J. R. Finney ◽  
B. A. G. Knight
Keyword(s):  
Winter Wheat ◽  
Root Development ◽  
Soil Physical Properties ◽  
Seminal Root ◽  
Cereal Crops ◽  
Extension Rate ◽  
Cultivation Systems ◽  
Physical Conditions ◽  
Cultivated Soil ◽  
Lower Bulk Density

SummaryThe results of a field experiment on winter wheat are presented in which the effects of the soil physical properties produced by different cultivation systems were studied in relation to root development.The extension rate of the seminal root axes was slower in undisturbed or shallow (5 cm) cultivated soil than in ploughed or deep (20 cm) cultivated soil leading to earlier lateral branching and the production of an effectively shallower seminal root system which persisted throughout the season. During the first four weeks after drilling the soil in the ploughed and the deeper cultivated plots was of lower bulk density and there were more pores of a diameter suitable for unimpeded root extension. It is suggested that seminal root development in uncultivated soils, which are less readily deformed than cultivated ones, is related to the probability of the extending seminal axes contacting pores of suitable dimensions.The implications of shallower rooting are discussed and related to field experience with cereal crops drilled directly into uncultivated soils where success has consistently been achieved on free-draining, open-textured soils.

ROOT DEVELOPMENT AND DISTRIBUTION IN RELATION TO SOIL PHYSICAL CONDITIONS ON FOUR DIFFERENT NATIVE GRASSLAND SITES FERTILIZED WITH NITROGEN AT THREE DIFFERENT RATES

1969 ◽  
Vol 49 (6) ◽  
pp. 753-760 ◽  
Author(s):  
Harold Goetz
Keyword(s):  
Bulk Density ◽  
Root Development ◽  
Nitrogen Fertilizer ◽  
Nitrogen Fertilization ◽  
Root Production ◽  
Soil Profiles ◽  
Physical Conditions ◽  
Native Grassland ◽  
Nitrogen Treatment ◽  
Nitrogen Treatments

Root production was slightly increased by nitrogen fertilization on four range sites. A major portion of the total root material was found in the upper 15.2-cm layer of the soil profiles on the Vebar, Rhoades, and Manning sites. A greater proportion of the root material was located at deeper depths in the Havre profile. Significant root increases were observed on the Vebar at the 37-kg nitrogen treatment, mainly at the 0- to 30.5-cm depth and on the Havre site at the 0- to 15.2-cm depth with 75 and 113 kg nitrogen per hectare. Significant increases were observed at the 0- to 15.2-cm and 30.5- to 45.7-cm depths only at the 75- and 113-kg nitrogen treatments on the Rhoades site. Statistically significant differences were observed between control plots and the 113-kg nitrogen treatment at the 15.2- to 30.5-cm depths on the Manning site. Bulk density decreased with increasing rates of nitrogen fertilizer on the Vebar and Manning sites.

Root development under fluctuating soil physical stress – plastic and elastic responses

2020 ◽  
Author(s):  
Tino Colombi ◽  
Hanna Sjulgård ◽  
Daniel Iseskog ◽  
Thomas Keller
Keyword(s):  
Growth Rate ◽  
Root Growth ◽  
Root Development ◽  
Optimal Growth ◽  
Penetration Resistance ◽  
Growth Conditions ◽  
Physical Stress ◽  
Soil Air ◽  
Physical Conditions ◽  
Root Growth Rate

<p>Physical properties of soil such as penetration resistance and oxygen concentration of soil air strongly influence root system development in plants. Soils typically exhibit considerable spatial and temporal fluctuations in penetration resistance and oxygen concentration of soil air due to wetting-drying cycles, small-scale differences in soil compactness or hotspots of biological activity. Hence, roots of a single plant are exposed to different physical environments and thus physical stresses during their growth through the soil profile. Plants are known to adjust their root development to these spatiotemporal fluctuations in soil physical conditions. Such phenotypic adjustments include changes of root growth rate as well as alterations of root morphology and anatomy. However, these adjustments reduce accessibility of water and nutrients and may increase the carbon demand for soil exploration, which limits aboveground plant development. Until now, it is unclear whether such adjustments in root development are plastic (i.e. the phenotype is irreversibly changed even when roots re-enter zones with optimal growth conditions) or elastic (i.e. the phenotype is only temporarily changed and recovers again when roots re-enter zones with optimal growth conditions).</p><p>To investigate the plasticity and elasticity of root development, we designed customized microrhizotrons in which soil penetration resistance and the concentration of oxygen in soil air can be varied. Near-infrared (λ=830 nm) time-lapse imaging was applied to quantify root growth rates, and combined with measurements of root morphology and anatomy. A series of experiments was conducted using different crop species with contrasting root system properties (fibrous vs. taproot system, thin vs. thick roots). After an establishment period of three days under optimal growth conditions, roots were exposed for 24 hours to increased penetration resistance, hypoxia and the combination of both stresses. Following this, the stress was released, and plants continued to grow for 24 hours at optimal conditions, before a second stress was applied for another 24 hours. Generally, root development responded to changes in soil physical conditions across all species. However, depending on the species, the adjustments in root development were found to be constant or temporary, i.e. plastic or elastic. This difference between species was particularly pronounced for root growth rate. Root growth rate in pea recovered after soil physical stress was released, while root growth rate in wheat remained low after stress release. The obtained findings will be discussed with respect to the tolerance of different plants to soil physical stress as well as the effects of root growth on soil structure dynamics.</p>

Comparison of direct drilling, reduced cultivation and ploughing on the growth of cereals

1977 ◽  
Vol 89 (3) ◽  
pp. 631-643 ◽  
Author(s):  
F. B. Ellis ◽  
J. G. Elliott ◽  
B. T. Barnes ◽  
K. R. Howse
Keyword(s):  
Root Development ◽  
Available Phosphorus ◽  
First Year ◽  
Nutrient Distribution ◽  
Physical Conditions ◽  
Seminal Roots ◽  
Different Depths ◽  
Direct Drilling ◽  
Phosphorus And Potassium ◽  
Made In

SummaryThis paper gives measurements of soil physical conditions and root growth made in the experiment described in the previous paper. The effect of methods of tillage on soil properties (strength, bulk density, nutrient distribution and fauna) and the effects on root development and the absorption of nutrients from different depths in the soil were investigated. The procedures used for these measurements are described.Greater soil compaction occurred in all years after direct drilling. The growth of seminal roots of young plants was reduced by direct drilling in each year but only in the first year were there significant differences in root development between treatments at later stages of growth. Similarly, in each year early shoot growth was reduced by direct drilling but, with the exception of the first year, the plants were subsequently able to compensate adequately. Direct drilling resulted in more earthworms being present in the soil, and caused the surface soil to be more friable and contain a higher concentration of available phosphorus and potassium.

Influence of Magnetic Fields on Solar Hydrodynamics: Experimental Results

1977 ◽  
Vol 36 ◽  
pp. 143-180 ◽  
Author(s):  
J.O. Stenflo
Keyword(s):  
Solar Activity ◽  
Energy Balance ◽  
Magnetic Fields ◽  
Solar Atmosphere ◽  
General Problem ◽  
Solar Rotation ◽  
Active Regions ◽  
Physical Conditions ◽  
Dynamic Phenomena

It is well-known that solar activity is basically caused by the Interaction of magnetic fields with convection and solar rotation, resulting in a great variety of dynamic phenomena, like flares, surges, sunspots, prominences, etc. Many conferences have been devoted to solar activity, including the role of magnetic fields. Similar attention has not been paid to the role of magnetic fields for the overall dynamics and energy balance of the solar atmosphere, related to the general problem of chromospheric and coronal heating. To penetrate this problem we have to focus our attention more on the physical conditions in the ‘quiet’ regions than on the conspicuous phenomena in active regions.

Photosynthetic responses of citrus trees to soil flooding

1991 ◽  
Vol 81 (1) ◽  
pp. 7-14 ◽  
Author(s):  
Joseph C. V. Vu ◽  
George Yelenosky
Keyword(s):  
Soil Flooding ◽  
Photosynthetic Responses ◽  
Citrus Trees

Platelet Aggregation Induced in Vitro by Therapeutic Ultrasound

1977 ◽  
Vol 38 (03) ◽  
pp. 0640-0651 ◽  
Author(s):  
B. V Chater ◽  
A. R Williams
Keyword(s):  
Platelet Aggregation ◽  
Direct Action ◽  
Adenosine Diphosphate ◽  
Ultrasonic Cavitation ◽  
Related Phenomenon ◽  
Release Reaction ◽  
Physical Conditions ◽  
Platelet Aggregates ◽  
Active Substances

SummaryPlatelets were found to aggregate spontaneously when exposed to ultrasound generated by a commercial therapeutic device. At a given frequency, aggregation was found to be a dose-related phenomenon, increasing intensities of ultrasound inducing more extensive and more rapid aggregation. At any single intensity, the extent aggregation was increased as the frequency of the applied ultrasound was decreased (from 3.0 to 0.75 MHz).Ultrasound-induced platelet aggregation was found to be related to overall platelet sensitivity to adenosine diphosphate. More sensitive platelets were found to aggregate spontaneously at lower intensities of sound, and also the maximum extent of aggregation was found to be greater. Examination of ultrasound-induced platelet aggregates by electron microscopy demonstrated that the platelets had undergone the release reaction.The observation that haemoglobin was released from erythrocytes in whole blood irradiated under identical physical conditions suggests that the platelets are being distrupted by ultrasonic cavitation (violent gas/bubble oscillation).It is postulated that overall platelet aggregation is the result of two distinct effects. Firstly, the direct action of ultrasonic cavitation disrupts a small proportion of the platelet population, resulting in the liberation of active substances. These substances produce aggregation, both directly and indirectly by inducing the physiological release reaction in adjacent undamaged platelets.

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