Growth and physiological responses of the citrus rootstock Swingle citrumelo seedlings to partial rootzone drying and deficit irrigation

2010 ◽  
Vol 148 (5) ◽  
pp. 593-602 ◽  
Author(s):  
J. C. MELGAR ◽  
J. M. DUNLOP ◽  
J. P. SYVERTSEN
Keyword(s):  
Root Length ◽  
Deficit Irrigation ◽  
Root Zone ◽  
Specific Root Length ◽  
Total Content ◽  
Dry Weight ◽  
Citrus Rootstock ◽  
Irrigation Treatments ◽  
Partial Rootzone Drying ◽  
Swingle Citrumelo

SUMMARYThe effects of deficit irrigation (DI) and partial rootzone drying (PRD) on the growth and mineral nutrition of citrus rootstock seedlings in the glasshouse were determined, as well as the potential of DI and PRD to trigger root-to-shoot signalling of abscisic acid (ABA) to increase the growth per amount of water used (water use efficiency (WUE)). In the DI study, 3-month-old seedlings of the important citrus rootstock Swingle citrumelo with intact roots received three irrigation treatments: control (1·00 evapotranspiration (ET)), 0·75 ET and 0·50 ET. DI clearly decreased growth, the net assimilation of CO2 (ACO2), WUE and the total content of N and K in leaves, even though concentrations of leaf N and K were increased in the drought-stressed smaller plants. Root K was not affected by DI treatments. Leaf ABA concentration increased linearly with DI. For the PRD study, root systems of 6-month-old Swingle citrumelo were split into half and allowed to become established in adjacent pots. There were three irrigation treatments: control (1·00 of the total crop ET, 0·50 in each pot), PRD 50-0 (0·50 ET by weight applied to only one-half of root zone) and DI 25-25 (0·50 ET in total, with 0·25 ET applied to each root half). Although the total root length was decreased by the DI 25-25 treatment, PRD 50-0 did not affect any growth characteristics compared to control plants. The dry root zone of the PRD 50-0 treatment had a higher specific root length, longer roots per dry weight, than the wet root zone. Leaf ACO2 and WUE of the DI 25-25 treatment were significantly lower than control plants after 11 weeks. Although the total contents of N and K in leaves were not affected by either PRD treatment, the concentrations of N and K in leaves were increased by DI 25-25. Root K was decreased by PRD treatments. Leaf ABA concentration was increased by PRD 50-0 but not by DI 25-25. Although all drought stress treatments increased the levels of ABA in leaves, DI and PRD treatments did not affect the whole plant WUE. Compared to well-irrigated control plants, DI reduced growth, whereas PRD 50-0 did not.

scholarly journals Novel approaches to improving growth of pasture legumes at low phosphorus levels

2014 ◽  
Vol 76 ◽  
pp. 197-202
Author(s):  
S.N. Nichols ◽  
J.R. Crush
Keyword(s):  
White Clover ◽  
Root Length ◽  
Specific Root Length ◽  
Root Traits ◽  
Dry Weight ◽  
Root Weight ◽  
Soil P ◽  
P Acquisition ◽  
Shoot Dry Weight ◽  
Use Efficiency

Abstract Strategies to reduce the economic and environmental costs of phosphate (P) fertiliser use in mixed pastures through plant breeding are focussed on inefficiencies in the legume component. One approach is breeding within white clover for root systems with improved P acquisition properties. Selection for root length per unit root weight (specific root length, SRL) showed that higher SRL plants could retain more biomass in the above ground fraction with decreasing soil P, whereas plants with lower SRL diverted more biomass to roots. Back cross 1 (BC1) generation interspecific hybrids between white clover and a wild relative, Trifolium uniflorum L., may possess additional root traits influencing P acquisition. In glasshouse experiments, some T. repens × T. uniflorum hybrids, back-crossed to white clover, also exhibited higher shoot dry weight than their white clover cultivar parents at low nutrient supply levels and low to intermediate soil Olsen P. This, combined with low internal P concentrations, suggests some BC1 hybrids may be more tolerant of low soil P than white clover. Differences in both P acquisition ability and internal P use efficiency may contribute to the observed yield differences. There are good prospects for delivery of new-generation clover cultivars with improved phosphate use efficiency to New Zealand farmers. Keywords: phosphorus, white clover, Trifolium uniflorum, interspecific

scholarly journals VESICULAR-ARBUSCULAR MYCORRHIZAL (VAM) FUNGI ALTER ROOT GROWTH OF PROSOPIS ALBA (CHILEAN MESQUITE) IN CONTAINERS

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 688f-688
Author(s):  
Chris A. Martin ◽  
Jean C. Stutz ◽  
Robert W. Roberson
Keyword(s):  
Growth Medium ◽  
Root Length ◽  
Glomus Intraradices ◽  
Salt Lake ◽  
Salt Lake City ◽  
Specific Root Length ◽  
Dry Weight ◽  
Root Systems ◽  
Peat Moss ◽  
Vam Fungi

Effects of VAM fungal inoculum, Glomus intraradices Schenk & Smith, on the growth of Chilean mesquite in containers were investigated as part of a nursery container system for production of xeric trees. Seedling liners of Chilean mesquite were transplanted into 27-liter containers filled with a 3 pine bark : 1 peat moss : 1 sand medium. Before transplanting, 50% of the trees were band-inoculated at a depth of 8 to 12 cm below the growth medium surface with 35 g per container of Glomus intradices (Nutrilink, NPI, Salt Lake City, UT), approximately 1,000 spores g-1. All trees were top-dressed with 15 g Osmocote 18N-2.6P-9.9K (Grace-Sierra, Milpitas, CA) and 3 g Micromax (Grace-Sierra, Milpitas, CA) fertilizers and grown in a fiberglass greenhouse under 50% light exclusion. After 4 months, all inoculated tree root systems were colonized, and the percent infection was 47%. Noninoculated trees remained nonmycorrhizal. There were no differences in height, total shoot length, shoot dry weight, or root dry weight between inoculated and non-inoculated trees; however, total root length and specific root length of inoculated trees were less than those of noninoculated trees. These results suggest that the VAM fungi altered the root architecture of inoculated trees such that root systems of these trees had thicker roots with fewer fine roots elongating into the growth medium profile.

Modeling N Concentration and Uptake for Maize Hybrids under Growth Stage-Based Deficit Irrigations

2017 ◽  
Vol 60 (6) ◽  
pp. 2067-2081 ◽  
Author(s):  
Quanxiao Fang ◽  
Liwang Ma ◽  
Thomas J. Trout ◽  
Louise H. Comas ◽  
Kendall C. DeJonge ◽  
...  
Keyword(s):  
Deficit Irrigation ◽  
Root Zone ◽  
N Uptake ◽  
Quality Model ◽  
Maize Hybrid ◽  
Maize Hybrids ◽  
N Concentration ◽  
Irrigation Treatments ◽  
Crop N Uptake ◽  
N Demand

Abstract. Current maize hybrids have lower critical aboveground biomass nitrogen (N) concentration (TCNP) and grain N concentration (GNC) compared to older hybrids, but few crop models have incorporated this trend. The objective of this study was to evaluate alternative algorithms for calculating TCNP (biomass-based method) and GNC (grain N demand based on N dilution curve) for predicting crop N concentration and N uptake for a current maize hybrid in the CERES-Maize model as implemented in the Root Zone Water Quality Model (RZWQM). Experimental data were obtained from a field study on maize irrigated to meet various percentages (40% to 100%) of evapotranspiration demand at both vegetative and reproductive stages in 2012 and 2013 in Greeley, Colorado. The original RZWQM showed little response of aboveground N concentration (AGBNC) to the irrigation treatments and overpredicted GNC in both years. As a result, crop N uptake was generally overpredicted, with root mean square error (RMSE) values of 28 to 60 kg N ha-1 for the two years. Adjusted coefficients in the original TCNP and GNC algorithms (RZWQM_ADJ) effectively reduced the overpredicted GNC but with less improvement in response to the irrigation treatments in 2013 compared with the original RZWQM simulations. The RZWQM with modified TCNP and GNC algorithms simulated lower GNC and AGBNC than the original version, significantly improved the responses to the irrigation treatments, and captured the variations in measured GNC among seasons. The corresponding crop N uptake simulations improved more in 2012 than in 2013, with lower RMSE values of 16 to 32 kg N ha-1 than the original and RZWQM_ADJ versions. The better-predicted grain N uptake by the alternative algorithms could be helpful to making better crop N management decisions under different deficit irrigation conditions. Keywords: CERES-Maize, Crop N concentration, Crop N demand, Crop N uptake, Deficit irrigation, Maize hybrid, RZWQM.

scholarly journals Ameliorative effect of Ascorbic acid and biochar on Growth, and antioxidant enzymes on early Seedling of Sorghum under Salinity Conditions

2021 ◽  
Author(s):  
Aboagla Elsiddig ◽  
Guisheng Zhou ◽  
Nimir Ahmed
Keyword(s):  
Ascorbic Acid ◽  
Antioxidant Enzymes ◽  
Root Length ◽  
Specific Root Length ◽  
Dry Weight ◽  
Controlled Study ◽  
Emergence Rate ◽  
Sorghum Seedling ◽  
Physiological Attributes ◽  
Total Dry Weight

Abstract Salt stress is one of the major environmental stresses that limits the growth, antioxidant defense and sustainable crop productivity. A controlled study was done to determine the ameliorative effects of ascorbic acid (ASA) (0, 568, and 850 μM) and biochar (BC) (0, 2 and 4% BC [w/w]) on emergence, growth, and physiological attributes of sorghum grown under three salinity levels (0, 100, and 200 mM NaCl). High salinity stress significantly reduced emergence percentage, emergence rate, shoot length, root length, specific root length, total fresh weight (T.F.W), total dry weight (T.D.W), the activities of peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT), but increased malondialdehyde (MDA) content. At the 200 mM NaCl level, 850 μM ASA with 4% BC enhanced most of the physiological attributes determined. At the 200 mM salinity level, total dry weight of sorghum seedling was increased by 42.7% and 23.1% at 2% and 4% BC levels, respectively as compared with non-BC control. The highest emergence rate at 200 mM NaCl was achieved at 4% BC and 850 μM ASA level. Our study suggested that the combined application of ASA and BC at appropriate amount and concentration on sorghum seedling may be helpful in salt tolerance and getting increase antioxidant enzymes that mitigate harms affected by saline problems worldwide.

scholarly journals In situ Root Phenotypes of Cotton Seedlings Under Phosphorus Stress Revealed Through RhizoPot

2021 ◽  
Vol 12 ◽  
Author(s):  
Zichen Zhang ◽  
Lingxiao Zhu ◽  
Dongxiao Li ◽  
Nan Wang ◽  
Hongchun Sun ◽  
...  
Keyword(s):  
Growth Rate ◽  
Root Length ◽  
Root Length Density ◽  
Root Hairs ◽  
Specific Root Length ◽  
Dry Weight ◽  
P Deficiency ◽  
Branch Density ◽  
P Absorption

Phosphorus (P) deficiency is a common challenge in crop production because of its poor mobility through the soil. The root system plays a significant role in P absorption from the soil and is the initial indicator of low P levels. However, the phenotypic dynamics and longevity of cotton roots under P stress remain unknown. In this study, RhizoPot, an improvised in situ root observation device, was used to monitor the dynamics of root phenotypes of cotton seedlings under P-deficient (PD) and P-replete (PR) conditions. Low P stress reduced P absorption and accumulation in the roots, leading to low dry weight accumulation. Cotton seedlings responded to low P stress by increasing the number of lateral roots, specific root length, branch density, root length density, and length of root hairs. Additionally, the life span of root hairs was prolonged. Low P stress also reduced the average diameter of roots, promoted root extension, expanded the root coverage area, and increased the range of P acquisition. Principal component analysis revealed that the net root growth rate, root length density, root dry weight, P absorption efficiency, average root hair length, and taproot daily growth significantly influenced the cotton root architecture. Collectively, these results show that low P stress reduces the net growth rate of cotton seedling roots and restricts plant growth. Plants respond to P deficiency by extending the life span of root hairs and increasing specific root length and lateral root branch density. This change in root system architecture improves the adaptability of plants to low P conditions. The findings of this study may guide the selection of cotton varieties with efficient P utilization.

scholarly journals 590 Growth and Physiological Characteristics of Diploid and Tetraploid Citrus Rootstock Seedlings Grown at Elevated CO2

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 548D-548 ◽  
Author(s):  
J.P. Syvertsen ◽  
J.W Grosser ◽  
L.S. Lee
Keyword(s):  
Gas Exchange ◽  
Plant Growth ◽  
Water Use ◽  
Root Length ◽  
Weight Ratio ◽  
Dry Weight ◽  
Nutrient Concentrations ◽  
Volkamer Lemon ◽  
Citrus Rootstock ◽  
Leaf N

We grew three diploid (2X) Citrus rootstock seedlings and their autotetraploids (4X) at elevated CO2 to obtain insights into limitations on growth and net gas exchange that have been associated with tetraploidy. Well-nourished Volkamer lemon (Volk), Troyer citrange (Troy), and Cleopatra mandarin (Cleo) were grown in greenhouses at ambient or twice ambient CO2 for 3 months. We measured plant growth, water relations, mineral nutrition, and net gas exchange characteristics of leaves. Overall, tetraploid roots were thicker as 4X had lower root length: dry weight ratio or specific root length (SRL) than 2X roots. Tetraploid plants were smaller and had higher root/shoot ratios, shorter fibrous roots, and lower whole plant transpiration than 2X. Tetraploids also had lower leaf N and P concentrations on a dry weight basis. Since 4X leaves had thicker leaves (more dry weight per area) than 2X leaves, these nutrient differences disappeared when expressed on an leaf area basis. Elevated CO2 increased plant growth but decreased leaf N, P, and K apparently by a growth dilution effect. Elevated CO2 also increased fibrous root thickness, leaf thickness, and net assimilation of CO2 (ACO2) but decreased stomatal conductance and transpiration such that leaf water use efficiency increased. There was no effect of ploidy level on ACO2 but 4X Volk and Troy had lower rates of ACO2 than their diploids at elevated CO2. Hydraulic conductivity of intact root systems (measured in a pressure pot) was correlated to total plant growth but variability obscured effects of CO2 or ploidy on root conductivity. The low SRL of tetraploids were correlated with lower rates of water use and lower leaf nutrient concentrations, which may be operative in determining the growth characteristics associated with tetraploidy.

scholarly journals Fertigation Frequency Affects Growth and Water and Nitrogen Use Efficiencies of Swingle Citrumelo Citrus Rootstock Seedlings

HortScience ◽  
2010 ◽  
Vol 45 (8) ◽  
pp. 1255-1259 ◽  
Author(s):  
Juan Carlos Melgar ◽  
Arnold W. Schumann ◽  
James P. Syvertsen
Keyword(s):  
Water Use ◽  
N Uptake ◽  
Dry Weight ◽  
Irrigation Frequency ◽  
N Uptake Efficiency ◽  
Citrus Rootstock ◽  
Use Efficiency ◽  
Swingle Citrumelo ◽  
Fertilizer Solution ◽  
Leaf N

We determined if frequency of application of irrigation water plus fertilizer in solution (fertigation) could modify root and shoot growth along with growth per unit nitrogen (N) and water uptake of seedlings of the citrus rootstock Swingle citrumelo growing in a greenhouse. In the first experiment, all plants received the same amount of water with sufficient fertilizer N but in three irrigation frequencies applied in 10 1.5-mL pulses per day, one 15-mL application per day, or 45 mL applied every 3 days. Plants irrigated at the highest frequency grew the least total dry weight and had the highest specific root length. Plants with lowest irrigation frequency grew the most and used the least water so had the highest water use efficiency. There were no irrigation frequency effects on relative growth allocation between shoot and roots, net gas exchange of leaves, or on leaf N. A second experiment used identical biweekly irrigation volumes and fertilizer rates, but water and fertilizer were applied using four frequency combinations: 1) daily fertigation; 2) daily irrigation with fertilizer solution applied every 15 days; 3) fertigation every 3 days; or 4) irrigation every 3 days and fertilizer solution applied every 14 days. Total plant growth was unaffected by treatments, but the highest frequency using the lowest fertilizer concentration grew the greatest root dry weight in the uppermost soil depths. Roots grew less and leaf N was highest when N was applied every 15 days, implying that root N uptake efficiency was increased when fertigated with the highest fertilizer concentration. All plants had similar water use efficiencies. A third experiment was conducted with irrigation every 3 days and with four different N application frequencies: every 3, 6, 12, or 24 days using four fertilizer concentrations but resulting in similar total N amounts every 24 days. There were no differences in growth, gas exchange, or water use efficiency. Given the fact that all treatments received adequate and equal amounts of water and fertilizer, fertigation frequency had only small effects on plant growth, although very high frequency fertigation decreased N uptake efficiency.

Testing the ability of organic ligands and plant materials to reduce the toxic effects of aluminium in soils

2004 ◽  
Vol 55 (1) ◽  
pp. 13 ◽  
Author(s):  
Sahta Ginting ◽  
Bruce B. Johnson ◽  
Sabine Wilkens
Keyword(s):  
Plant Growth ◽  
Root Length ◽  
Root Zone ◽  
Acid Soil ◽  
Dry Weight ◽  
Organic Ligands ◽  
Surprising Result ◽  
Plant Materials ◽  
Soil Systems ◽  
Amended Soil

An acid soil from the Sedgwick region of central Victoria was modified to provide a range of aluminium (Al) concentrations in order to test whether incorporation of organic ligands, or plant material, could reduce plant-available (or 'reactive') Al in soils. Al concentrations in the soil were increased by addition of varying amounts of a solution of AlK(SO4)2, chosen after measurement of the adsorption of Al onto the soil. A similar study of citrate adsorption allowed estimation of the amount of citrate required to achieve a 1 : 1 Al : citrate ratio in the soil in order to test the effectiveness of organic ligands in alleviating Al toxicity. Citrate was found to decrease the level of reactive Al in the soil. Pot trials also showed that addition of citrate to Al amended soil caused some improvement in root length and dry weight of soybean plants (Glycine max) compared with the Al amended soil. Addition of oxalate also reduced the level of reactive Al but did not improve root growth. Incorporation of dried leaves from lucerne (Medicago sativa), rhubarb (Rheum rhubarbarum), oxalis (Oxalis pes-caprae), and soybean at application rates equivalent to 5 and 10 t/ha to a soil containing added Al tended to increase root length. The most surprising result was the relatively small effect of high Al concentrations on plant growth, with 2000 μm reactive Al reducing root length by only 50% after 15 days of growth. This is a much smaller reduction in root length than has previously been obtained in hydroponic systems with 500 μm reactive Al after 15 days growth (Ginting et al. 1998) and points to a major difference between plant growth trials in solution culture and soil systems. One possible explanation for this difference is that the roots are in contact with only a small volume of soil solution, and this can be modified by root exudates. Further research is required to test this hypothesis, which will require the development of a method of analysis for Al in soil systems that more accurately reflects reactive Al levels in the root-zone.

Effect of Penicillium bilaii inoculation and phosphorus fertilisation on root and shoot parameters of field-grown pea

2001 ◽  
Vol 81 (3) ◽  
pp. 361-366 ◽  
Author(s):  
J. Kevin Vessey ◽  
Krista G Heisinger
Keyword(s):  
Pisum Sativum ◽  
Root Morphology ◽  
Root Length ◽  
Specific Root Length ◽  
Dry Weight ◽  
Western Canada ◽  
Microbial Inoculants ◽  
P Nutrition ◽  
P Content ◽  
Phosphorus Fertilisation

The mechanisms underlying the stimulating effect of Penicillium bilaii inoculation on the growth of crop plants are not clear. The effect of P. bilaii inoculation on root morphology [dry weight (DW), length and specific root length) and other root and shoot parameters of pea were investigated at two field sites in western Canada in 1996. Pea (Pisum sativum L.) was grown at three levels of P fertilization (0, 6.4 and 19.3 kg ha–1) at Ellerslie, AB, and Outlook, SK. Shoot dry matter, P concentrations, P content and nodulation were also measured in pea plants harvested at the seven- to nine-node stage. Soil cores were used to sample roots. Although plants were responsive to P fertiliser at both sites, P. bilaii inoculation affected pea growth at the Ellerslie site only. At this site, P. bilaii inoculation increased root length by 48%, specific root length (m g–1 root DW) by 21%, root DW by 13%, and shoot P concentration by 13% in treatments that received no P fertiliser. We suggest that the stimulating effect of P. bilaii inoculation on crop P nutrition is partly explained by increases in root absorptive capacity in the presence of the fungus. However, this effect was only significant under P-limited conditions. Key words: Microbial inoculants, Pisum sativum, Penicillium bilaii, phosphorus, root length, root morphology

scholarly journals Differences in Seedling Growth of 23 Creeping Bentgrass Cultivars under Polyethylene Glycol-induced Drought Conditions

2018 ◽  
Vol 28 (3) ◽  
pp. 327-331 ◽  
Author(s):  
Qi Zhang ◽  
Liqi Yang ◽  
Kevin Rue
Keyword(s):  
Polyethylene Glycol ◽  
Seedling Growth ◽  
Root Length ◽  
Crop Production ◽  
Weight Ratio ◽  
Specific Root Length ◽  
Creeping Bentgrass ◽  
Dry Weight ◽  
Shoot Dry Weight ◽  
Stress Damage

Drought is the most important abiotic stress in crop production including turfgrass management. Using drought tolerant plants can help minimize stress damage. In this study, 23 commercially available cultivars of creeping bentgrass (Agrostis stolonifera) were evaluated for their responses to drought stress that was induced by polyethylene glycol (PEG) 6000 in a hydroponic system during the seed germination and seedling growth stage. In such a system, water potential was adjusted to 0.0 (the control), −0.3, and −0.6 MPa to mimic the drought condition. The absolute water content (AWC), shoot dry weight (SDW), root dry weight (RDW), longest root length (LRL), specific root length (SRL), and root-to-shoot dry weight ratio (RSR) in the plants grown for 4 weeks in the treatment were determined. Results showed that SDW and LRL were unaffected by drought; however, RDW and RSR increased, whereas SRL and AWC were reduced under drought. Among the 23 creeping bentgrass cultivars evaluated, Independence and Crystal Bluelinks had a higher turfgrass performance index (TPI), which represented the number of times a cultivar ranked in the top statistical group across all parameters. The results suggest that ‘Independence’ and ‘Crystal Bluelinks’ may be more adapted to drought than the other cultivars at the seedling stage.

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