Plant Root Dry Weight Research Articles

Effect of salinity and seed priming on growth and biochemical parameters of different barely genotypes

An experiment was conducted to investigate the interactive effect of salinity and seed priming on barely genotypes at the Institute of Biotechnology and Genetic Engineering (IBGE), Khyber Pakhtun Khwa Agricultural University Peshawar Pakistan. The experiment was carried out in completely randomized design (CRD) with three replications consisting of twelve barely genotypes (Haider-93, Soorab-96, Arabic Asward, NRB-37, Frontier-87, Jau-83, Balochistan-Local, NRB-31, KPK-Local, Sanober-96, Awarn-2002 and AZ-2006) at two seed conditions (seed priming with 30 mM NaCl or no seed priming) under four salinity levels (0, 50, 100 and 150 mM). The results revealed that seed priming and salinity had significantly (p≤0.05) affected all the parameters under study. However, the effect of seed priming was non significant (p>0.05) on shoot chlorophyll a content (mg g -1 fresh weight) and root sugar content (mg g -1 dry weight). Salinity stress had adversely affected growth and biochemical parameters of barley genotypes, however, seed priming with NaCl had diminished the negative impact of salt stress. Maximum shoot dry weight plant -1 (1.81 g), root dry weight plant -1 (0.42 g), shoot K + content (1.41 mg g -1 dry weight), root sugar content (7.55 mg g -1 dry weight) were recorded in Balochistan-Local. Similarly, Haider-93 produced highest root K + content (0.67 mg g -1 dry weight), shoot sugar content (16.36 mg g -1 dry weight), shoot chlorophyll a content (3.44 mg g -1 fresh weight) and shoot chlorophyll b content (1.78 mg g -1 fresh weight). Maximum shoot Na + content (1.20 mg g -1 ) and root Na + content (1.47 mg g -1 ) was recorded in Frontier-87. Seed priming had significantly (P<0.05) enhanced all the aforementioned parameters. The positive effect of seed priming was more profound in Balochistan-Local followed by Haider-93 as compared to other genotypes. Key words : Barely, salinity, seed priming, Na + , K + , chlorophyll a and b.

Effects on growth, yield, and fruit quality in tomato (Lycopersicon esculentum Mill.) using a mixture of potassium humate and farmyard manure as an alternative to mineral-N fertiliser

SummaryThe effects of potassium humate (KH) mixed with farmyard manure (FYM), as an alternative to mineral-N fertiliser, on the growth, leaf mineral composition, fruit yield and quality of tomato on newly-reclaimed soil were investigated. Mixtures of KH and FYM were applied at the rates of 50 kg KH + 25 metric tonnes (MT) FYM, 50 kg KH + 50 MT FYM, 100 kg KH + 25 MT FYM, and 100 kg KH + 50 MT FYM ha–1. No mineral-N fertiliser was included in any of these treatments. In addition, the recommended dose of mineral-N fertiliser was used as a control. Significant positive effects of 100 kg KH + 50 MT FYM ha–1 were observed on shoot dry weight (DW) plant–1, root DW plant–1, leaf free proline content, leaf mineral composition (N, P, K, Fe, Mn, and Zn), leaf and fruit nitrite (NO2–) and nitrate (NO3–) contents, total fruit yield ha–1, and fruit vitamin C and total soluble solids (TSS) contents when compared with the other three KH + FYM treatments. In contrast, there were no significant differences in these parameters between the 100 kg KH + 50 MT FYM ha–1 and the recommended mineral-N fertiliser treatments, except for leaf and fruit NO2– and NO3– contents, where significant reductions occurred in the 100 kg KH + 50 MT FYM treatment. The same trends were observed over two growing seasons (2008 and 2009).

Mitigation of salt stress in strawberry by foliar K, Ca and Mg nutrient supply

Plant root and shoot dry weight, leaf relative water content (LRWC) and chlorophyll content were reduced by 30%, 21%, 15%, 34%, respectively, at 40mM NaCl as compared to non-salt stress conditions. However, membrane permeability (MP) of plant increased (85.0%) with increasing salinity. Foliar nutrient application (FNA) alleviated deleterious effects of salinity stress on growth and this effect was statistically significant. The highest alleviation effect of FNA at 40mM salinity stress was observed in the case of 10mM foliar KNO&lt;sub&gt;3&lt;/sub&gt; and Ca(NO&lt;sub&gt;3&lt;/sub&gt;)&lt;sub&gt;2&lt;/sub&gt; application, resulting in increase in plant root dry weight (50%), shoot dry weight (50%), LRWC (8.2%) and MP decrease (27.4%) at 40mM NaCl. Phosphorus, Fe and Zn contents in shoots and roots of plants also increased with FNA treatments, but they were still much lower than those of non-salt stress treatment. Sulphur, P, Fe and Zn contents of shoots reached similar values as in non-salt stress treatment when KNO&lt;sub&gt;3&lt;/sub&gt; was applied, whereas Fe, Mn, Zn, and Cu contents of roots reached the values of non-salt stress treatment when Ca(NO&lt;sub&gt;3&lt;/sub&gt;)&lt;sub&gt;2&lt;/sub&gt; was applied.

Ameliorative Effect of Hydro Gel Substrate on Growth, Inorganic Ions, Proline, and Nitrate Contents of Bean under Salinity Stress

ABSTRACT The effect of varying hydrogel (0, 0.5, and 1.0% w/w) supply on some agro-physiological properties, such as dry matter, nutrient contents, chlorophyll contents, proline content, and ionic balance of bean plants in different salt sources and stress due to doses were investigated. Plants were treated with eight salt sources [sodium chloride (NaCl), sodium sulfate (Na2SO4), calcium chloride (CaCl2), calcium sulfate (CaSO4), potassium chloride (KCl), potassium sulfate (K2SO4), magnesium chloride (MgCl2), magnesium sulfate (MgSO4)] and four concentrations (0, 30, 60, and 120 mM doses) for 60 days in a growth media. Salt type, doses, and hydrogel (HG) affected the soil electrical conductivity. Soil salinity affected the parameters considered, and changed the nutrient balance of plants. High salt concentration caused substantial reduction in plant growth. Different salt concentrations negatively affected plant dry weight. The highest decrease of plant root dry weight was obtained with NaCl application followed by Na2SO4, CaCl2, CaSO4, MgCl2, MgSO4, KCl, and K2SO4, and similarly NaCl, Na2SO4, CaCl2, CaSO4, KCl, K2SO4, MgCl2, and MgSO4 in root dry weight. Total chlorophyll and nitrate contents of plants decreased with increasing salt doses, and the lowest value was obtained for NaCl application. Proline contents of plants were increased with increasing salt doses, and the highest value was obtained with the NaCl application. The effects of salt concentrations in nitrogen (N), potassium (K), and phosphorus (P) content of plants were significant. The presence of salt in the growth medium induced an important decrease the macro nutrient of the root and shoot part of plant such as N, P, K, calcium (Ca), and magnesium (Mg) content, but the N and P content of root and shoot part of the plant were increased with increasing of the HG application doses. The highest N and P increases were obtained with the 1.0 HG application for all salt types for both the root and shoots of plants. The HG added to saline soil significantly improved the variables affected by high salinity and also increased plant N and P, reduced soil electricity conductivity, nitrate, proline, and electrolyte leakage of plants, enhanced plant root and shoot dry weight by allowing nutrients and water to release to the plant as needed. The results suggested that HG has great potential for use in alleviating salinity stress on plant growth and growth parameters in saline soils of arid and semi-arid areas. This HG appears to be highly effective for use as a soil conditioner in vegetable growing, to improve crop tolerance and growth in saline conditions. It is intended to confirm the results of these studies by field trials.

Saprobe fungi decreased the sensitivity to the toxic effect of dry olive mill residue on arbuscular mycorrhizal plants

We studied the influence of olive mill dry residue (DOR) treated with saprobe fungi on growth of tomato and alfalfa colonized by Glomus deserticola. The application of 25 g kg −1 of dry DOR to soil decreased the shoot and root dry weight of tomato and alfalfa. Plants were more sensitive to the toxicity of DOR when colonized with the arbuscular mycorrhizal (AM) fungi. The sensitivity of both plants to the toxicity of DOR differed according to whether they were colonized by G. deserticola or by indigenous AM fungi. The phytotoxicity of DOR towards tomato and alfalfa was decreased by incubation the residue before planting with saprobe fungi for 20 wk. The beneficial effects of AM fungi on plant growth added with DOR incubated with saprobe fungi depend of the type of the plant and AM fungi. The contribution of AM fungi to the beneficial effect of DOR incubated with saprobe fungi varied according to the type of the plant and AM fungi. G. deserticola increased the shoot and root dry weight of plants when they were grown in the presence of DOR incubated with saprobe fungi for 20 wk. The beneficial effect of saprobe fungi on the dry weight and the level of AM mycorrhization of plants seem to be related to the decrease caused by these fungi in the phenol concentration in DOR. However, the toxicity of DOR due to substances other than phenols can not be ignored. The use of certain saprobe and AM fungi allows the possibility of using DOR as an organic fertilizer.

Studies on the effect of mycorrhization of potato roots on the hatching activity of potato root leachate towards the potato cyst nematodes, Globodera pallida and G. rostochiensis

Abstract Successful mycorrhization of potato plants cv. Golden Wonder was achieved with three commercial preparations of arbuscular mycorrhizal fungi (AMF): Vaminoc (mixed-isolate inoculum) and two of its components, Glomus intraradices and Glomus mosseae. Potato cyst nematode hatching assays were conducted on the potato root leachate (PRL) produced by inoculated and non-inoculated potato plants to examine the effect of AMF inoculation on the hatching response of the two PCN species, Globodera rostochiensis and G. pallida. The overall hatch response of G. rostochiensis to the potato root leachate was greater than G. pallida. Root leachates from Vaminoc- and G. mosseae-inoculated plants were found to stimulate the hatch of G. pallida in the first 3 weeks after shoot emergence. Fractionation of root leachates with standardised carbon content by Sephadex G-10 chromatography revealed multiple AMF effects on hatching factor (HF) production. Root leachates from Vaminoc-inoculated plants contained markedly more G. pallida-active HF than all other treatments; by contrast, PRL from the three AMF treatments exhibited little variation in the quantity of G. rostochiensis-active HF produced. Several HF were PCN species-specific or species-selective, with those resolved from the G. intraradices and G. mosseae PRL profiles exhibiting an apparent preference for G. rostochiensis rather than G. pallida. Mycorrhization also significantly increased the root dry weight of plants.

Shade acclimation in the forage grass Festuca Pallescens: biomass allocation and foliage orientation

Plants can acclimate to shade through different processes. In particular, they can modify their biomass allocation and the architecture in order to increase light interception. The objective of this study was to evaluate the shade acclimation capacity of Festuca pallescens (St. Ives) Parodi, as part of research concerning the use of this species in silvopastoral systems in Patagonia, Argentina. Biomass allocation was estimated from the leaf and root dry weights of plants growing in an open pasture and forested plots. Crown architecture of plants growing in the open and in two shade treatments was studied dividing each plant in three concentric cylinders, within which leaf angles and leaf area were measured. Light interception of plants in each treatment was estimated from the projected leaf areas and the relative amount of radiation reaching each location. Biomass allocation changed significantly in plants growing under shade conditions, increasing the proportion of leaves relative to the roots (Leaf Mass Fraction = 0.29 (SD: 0.12) and 0.40 (SD: 0.09) in plants in the open and under shade, respectively). Also, mean leaf inclination angles changed in plants growing under shade conditions, allowing an increase in light interception of approximately 35% compared to plants with the crown architecture typical of the open treatment. Previous studies have shown that F. pallescens does not change its photosynthetic response to light under shade conditions. Therefore, we conclude that the reported changes in biomass allocation and crown architecture, in addition to the increment in specific leaf area explain the relatively high shade tolerance of this species.

Growth and stress tolerance of tomato seedlings (Lycopersicon esculentum Mill.) in response to seed treatment with paclobutrazol

SUMMARY‘Marglobe’ tomato seeds were soaked (24 h at 22°C) or matric primed (-1.0 MPa for 7 d at 22° C) in 50 mgl-1 of paclobutrazol (PB), a triazole growth retardant. Plants from these treatments and from non-treated seeds or seedlings whose shoots were sprayed with 10 mg PB l-1 at 14 days after planting (DAP) were assessed for growth and physiological responses before and after factorially combined stresses of drought (a 14 d period of drying cycles until severe wilting) or heat (4 h at 50° C) were initiated at 24 DAP in the greenhouse. At 23 DAP, shoot heights and shoot and root dry weights of plants from PB-soaked seeds or PB-sprayed plants were similar, but lower than those from non-treated or PB-primed seeds. This pre-stress PB-mediated growth suppression was associated with greater stress tolerance as revealed by greater increases in shoot and root dry weights during the 10 d post-stress recovery period. Further support for the increased stress tolerance of plants from PB-soaked seeds or PB-sprayed plants than occurred with plants from non-treated seeds or PB-primed seeds was their higher leaf xylem pressure potential, lower leaf electrolyte leakage, and lower loss of leaf total chlorophyll during the 10 d post-stress recovery period.

Soil Aggregate Size Affects Phosphorus Desorption from Highly Weathered Soils and Plant Growth

Because plant absorption of P depends on the desorption of P from soil, understanding P desorption from soils may improve the precision of P diagnosis and fertilization recommendations. Many soils with high P retention due to high levels of Fe and Al are also highly aggregated. Extractable P is sometimes higher on larger size aggregates, which will probably result in increased P release from aggregates. The effects of aggregate size on P availability of three highly weathered soils were quantified with a column-leaching study and a pot experiment. Phosphorus desorption by leaching from small aggregates was greater than that from large aggregates when P had been added to the bulk soil (Kapaa and Leilehua soils) and a mixture of different-sized aggregates (Leilehua soil). When aggregates were separated and then P added, however, P desorption was greater from large aggregates (4-6 mm) than from small aggregates (<0.5 mm). Conformity of the P desorption data to the parabolic diffusion and expanded Elovich equations suggests that P desorption is probably controlled by diffusion processes. A pot experiment showed that total P in lettuce (Lactuca sativa L.) and soybean [Glycine max (L.) Merr.] ] shoots, and the root dry weights of plants grown in the large aggregates (2-6 mm) were higher than for plants grown in the small aggregates (<0.5 mm) after equal amounts of P were added to the separated aggregate fractions. Increased P uptake with increased aggregate size was attributed to increased P release from aggregates because of reduced P fixation. The results suggest that soil management that favors soil aggregation may, in some cases, increase availability of applied P. Perhaps the distribution of soil aggregates should be considered in making P management decisions.

Influence of soil impoverishment on the interaction between Glomus mosseae and saprobe fungi

The effect of the saprobe fungi Wardomyces inflatus (Marchal) Hennebert, Paecilomyces farinosus (Holm & Gray) A. H. S. Brown & G. Sm., Gliocladium roseum Bain., Trichoderma pseudokoningii Rifai and T. harzianum Rifai, isolated from sporocarps of Glomus mosseae, on arbuscular mycorrhizal (AM) colonisation and plant dry matter of soybean was studied in 2/3 and 1/5 diluted soils in a greenhouse trial. Soil dilution to 1/5 had no effect on shoot dry matter of soybean but decreased AM colonisation and root dry weight of plants. CFU of saprobe fungi, except T. harzianum, were higher in 1/5 than in 2/3 diluted soils. W. inflatus and Gliocladium roseum decreased the shoot dry weight of soybean plant when inoculated together with Glomus mosseae. The saprobe fungi P. farinosus and T. pseudokoningii increased the shoot dry weights of plants grown in 1/5 diluted soil. The shoot dry weight and AM colonisation in 1/5 diluted soil were also increased when T. harzianum was inoculated together with Glomus mosseae. Thus, saprobe fungi increased AM colonisation of soybean plants by indigenous endophytes. The AM colonisation of plants at both soil dilutions was increased by Glomus mosseae. The highest level of AM colonisation was observed when P. farinosus and T. pseudokoningii were inoculated together Glomus mosseae. The dilution of soils influenced the interaction between inoculated microorganisms and their effect on plant growth.

Phytophthora Root Rot of Blueberry Increases with Frequency of Flooding

Phytophthora root rot is a severe disease on blueberry (Vaccinium corymbosum L.) in poorly drained soils. Little is known about how mulching and frequent waterlogging affect disease severity in blueberries. Phytophthora cinnamomi Rands was grown on rice hulls, which were incorporated into the soil at the rate of 10% (v:v). Waterlogging conditions were imposed for 48 hours 1 week after planting on mulched and nonmulched blueberry plants at weekly, biweekly, and monthly intervals for a total of 3 months. Control plants were not subjected to flooding. The severity of Phytophthora root rot increased with time. Significant linear relationships were found between flooding interval and disease severity rating of shoot, percentage of root infection, and shoot and root dry weights of plants. Disease symptoms were minimal in control plants, but shoot disease rating and percentage of root infection were high in mulched and nonmulched plants that were flooded every week. Shoot and root dry weights were higher in 1997 than in 1996. In 1996, mulched plants had higher shoot dry weights than did nonmulched plants. Disease incidence was higher with weekly and biweekly flooding than with monthly or no flooding. However, mulching did not affect root infection.

Styrene-Lined and Copper-Coated Containers Affect Production of Cornus florida

Abstract Response of dogwood cultivars (Cornus florida ‘Barton's White’ and ‘Weaver's White’) to styrene lining and copper hydroxide coating of 10.3 liter (#3) black plastic containers was evaluated in 1993 and 1994. After the first growing season, dogwoods were either left in their original containers or repotted into untreated 23.3 liter (#7) containers. Copper hydroxide reduced root circling of both cultivars in containers; however, root dry weight of plants grown in copper-treated containers was reduced during the first season. Copper-treated containers resulted in less growth in height when plants were left in their original container during the second growing season and less trunk diameter growth of plants repotted into 23.3 liter (#7) containers. In the absence of copper, more surface root coverage and less surface root dieback occurred with plants grown in styrene-lined containers. Both cultivars grown the second season in their original styrene-lined containers had greater height increase than those in unlined containers. After being repotted into 23.3 liter (#7) containers, both cultivars originally grown in styrene-lined containers had greater trunk diameter growth than those in unlined containers.

Influence of Root Flooding Interval on Phytophthora Root Rot of Blueberry

Phytophthora root rot is a severe disease on blueberry (Vaccinium corymbosum L.) in poorly drained soils. The objective of the study was to determine the frequency of water-logged conditions on disease severity of blueberry. Phytophthora cinnamomi was grown on rice hulls and incorporated into the soil at the rate of 10% v/v. Water logging conditions were inflicted for 48 hr on mulched and non–mulched blueberry plants at 1-, 2-, and 4-week intervals. Non-water logging conditions were used on both mulched and non-mulched control plants. There was a significant linear relationship between disease severity of shoots and roots and the frequency of water-logging conditions. Disease symptoms were low in control plants, but disease ratings were high in mulched and non-mulched plants that were treated with water-logging conditions every week. There was also a linear trend between shoot dry weight and root dry weight of plants with frequency of water logging. Higher dry weights were seen on control plants. There was a significantly higher shoot, root dry weight and number of leaves of mulched plants than non-mulched plants. The percentage of infection on roots were high with frequent water logging. The study revealed high disease incidence with frequent water loggings. However, growth of mulched blueberry plants were comparable in control plants and plants that were subjected to water logging at 4-week intervals.

Response of Poinsettias to Paclobutrazol in Paint Applications

The effectiveness of a paclobutrazol/paint mix in controlling growth of poinsettia plants (Euphorbia pulcherrima) cultivars Freedom Red and Angelica Red was evaluated. Plants were grown in containers whose interior walls were coated with a flat latex impregnated with varying concentrations of paclobutrazol: 0, 5, 20, 80, 100, 150, 200, and 300 mg·L–1 (0. 0.032, 0.128. 0.512, 0.64, 0.96, 1.28, and 1.92 mg a.i. per container, respectively). As a comparison, one treatment consisted of plants drenched with 118 ml/container of a paclobutrazol solution at 3 mg·L–1. Plants grown in containers with the paint–paclobutrazol mix were shorter than the control plants. Treatments involving concentrations of 100 mg·L–1 or more (even as much as doubled or tripled) did not produce proportionately shorter plants. Root dry weights of plants in all treatments were not significantly different. However, the length of roots touching the internal surface of the container decreased with increasing growth regulator concentrations. This may help explain why doubling concentrations of growth regulator-in-paint does not produce proportionately shorter plants: roots start absorbing the growth regulator as soon as they touch the wall of the container. As a consequence, all root elongation is reduced, resulting in less root-growth regulator contact and less growth regulator uptake. More measurements of root length and root area are required in order to proof this hypothesis. When paclobutrazol concentrations were higher than 100 mg·L–1, some bracts showed evidence of “crinkling.”

The Effect of Salinity on Strawberry Stress and Growth on Two Soil Types

Plants of strawberry (Fragaria × ananassa cv. Tristar) of the same size were grown in 4-inch plastic plots either containing sand or organic soil mix. Plants were watered with solutions of 10, 25, and 50 mM of NaCl, and some with distilled water used as control. Under sunny conditions, the chlorophyll fluorescence measurements indicated that plants growing in sandy soil with 50 and 25 mM of NaCI with Fv/Fm values less than 0.40 tend to show salinity stress after 10 days with 50 mM NaCI, and after 15 days with 25 mM NaCI. Plants grown in organic soil mix do not show stress symptoms at any of the given NaCI concentrations. Plants growing under cloudy days do not show stress symptoms, whether or not the plants were grown in sandy soil or organic soil mix. No significant differences were detected on the total average shoot and root dry weights of plants grown in sandy soils and organic soil mix. However, highly significant differences was detected on the total average shoot dry weight growing under organic soil mix. These data indicate that organic matter reduces the effect of Na+ and Cl– on strawberry plant growth by decreasing the physiological stress during bright, sunny days. Plant tissue analysis shows that plants grown in organic soil mix absorb far less Na+ and Cl– than in sandy soil. Also, it does seem that strawberry plants can tolerate low concentrations of NaCI ions in the soil solution.

Yield and Dry Matter Partitioning of Strawberry Plants Grown with Three Preplant Soil Fumigation Treatments

Three preplant soil fumigation treatments were applied to a strawberry fruit production field in Summer 1993: 1) a mixture of 67 methyl bromide: 33 chloropicrin (wt/wt, 392 kg·ha–1) (MBC); 2) chloropicrin (trichloronitromethane, 336 kg·ha–1) followed by metam sodium (935 liters·ha–1) CMS); and 3) nonfumigation (NF). Bare-rooted `Camarosa' strawberry plants were established in each treatment on 1 Nov. in annual hill culture. Plant mortality was &lt;1%; thus, differences in growth and productivity among treatments were due to sublethal effects of competitive soil organisms. Fruit yields were recorded weekly from 14 Jan. to 23 May 1994. For the NF treatment, early season (January–March), late season (April–May), and total yields were 86%, 69%, and 72%, respectively, of those of the MBC treatment. Early season yields were greatest for the MBC treatment, but late and total yields were greatest for the CMS treatment. From Jan. through May 1994, 20 plants were destructively harvested from each treatment at about monthly intervals for determination of leaf (LDW), crown (CDW), and root dry weight (RDW). For a given date, LDW, CDW, and RDW of plants in the MBC and CMS treatments were greater than those of the NF plants. From January to March, plants in the NF treatment allocated a proportionally greater amount of dry matter to roots, and proportionally less dry matter to crowns and leaves than fumigated plants. In April and May, root: shoot ratios were similar for all three treatments. These data demonstrate the marked influence of soil fumigation treatment on yield and dry matter partitioning of strawberry, and suggest that combinations of chloropicrin and metam sodium may be a viable, albeit expensive, alternative to fumigation with methyl bromide.

Seed Size and Water Potential Effects on Germination and Seedling Growth of Winter Wheat

Published reports on the effects of seed size on wheat (Triticum aestivum L.) vigor are conflicting. The interactive effects of seed size and water stress on germination and early growth of wheat are perhaps important in this regard. Experiments were conducted to measure the effects of seed size and water potential on germination and seedling growth of the soft red winter wheat genotypes ‘Auburn’ and ‘Howell’. In a growth chamber germination test using solutions of mannitol, germination percentage (GP) was not affected by seed size, but osmoticum of −300 kPa reduced GP to 69 compared to 88 and 89 for the 0 and −100 kPa treatments, respectively. In greenhouse soil, shoot dry weight (SOW), root dry weight (ROW), and number of tillers (NT) of 4‐wk‐old seedlings from large seeds (35 mg seed−1) were larger than those of seedlings from medium (26 mg seed−1) and small (17 mg seed−1) seeds. Soil water potentials of −100 and −300 kPa decreased all three parameters compared to the control (−10 kPa). The GP in the greenhouse was reduced by low water potential, but was not affected by seed size. The genotype × water potential interaction was significant for SOW and ROW, but not for GP and NT; Howell was more susceptible to water stress than Auburn. At −10 kPa, 4‐wk‐old plants from small seeds had SDW and ROW that were 30 and 39% smaller, respectively, than those from large seeds, while at −300 kPa, SOW and ROW of plants from small seeds were 75 and 78% smaller, respectively, than those of plants from large seeds. The ability of larger seeds to produce larger seedlings than smaller seeds thus appears to be more pronounced under drought than under well‐watered conditions. While it is not known whether larger seedlings (with larger roots) would enhance water supply to the plant by exploring more soil, or would decrease the supply through more transpiration, faster early growth from larger seeds may be advantageous in establishing plants under dry soil conditions.

Root Temperature and Calcium Level Effects on Winter Wheat Forage: I. Shoot and Root Growth

AbstractWheat pasture poisoning is a metabolic disorder of ruminants, that occurs particularly in the spring, during a sudden spurt in plant growth, under conditions of optimum temperature, ample soil moisture and adequate mineral supply. To determine the effects of an increase in root temperature and four Ca levels on the shoot and root growth of winter wheat (Triticum aestivum L. ‘Centurk’), seedlings were grown under three root temperature regimes (constant 8 °C, constant 16 °C, and increasing from 8‐16 °C), in nutrient solutions with four Ca levels (0.2,0.6,2.0, and 5.0 mM). No significant differences due to Ca levels were found for growth rates of the shoots and roots (dry weight basis), nor for root extension rates. Growth rates of the shoots and roots (dry weight basis), and root extension rates were significantly slower for plants grown at 8 °C compared to those grown at 16 °C. Lateral root growth, in particular, was depressed in plants grown at a cold root temperature. The mean root diameter was significantly greater at 8 °C than at 16 °C, apparently due to the greater proportion of main root axes with larger root diameters at a cold root temperature. Plants transferred to 16 °C had growth rates of the shoots and roots that were intermediate, relative to those grown at constant low or constant high root temperatures. A lag period of 1 wk was observed before shoot and root dry weights of plants transferred to 16 °C increased, compared to those maintained at 8 °C. Thus, root temperatures play a major role in modifying shoot and root growth parameters.

Root-zone Temperature Affects Water Status and Growth of Red Maple

Abstract Red maple (Acer rubrum L.) plants were evaluated for their responses to 5 weeks of constant root-zone temperatures from 18 to 36C. Shoot lengths of plants grown with 18 to 30C root zones did not differ significantly from one another at any time during the study, and shoot dry weights of these plants were similar. However, after 21 days of exposure, shoot length of plants grown with roots at 36C was significantly less than that of plants with roots grown at 30C and below. Leaf area was greatest among plants with roots at 24C, and mean shoot and root dry weights of plants in the 36C treatment were 57% and 68% less, respectively, than those for plants with roots at 30C. Leaf diffusive resistance of plants grown at 36C was five times greater than for plants with root zones at 30C or below. Shoot water potential decreased with increasing temperature, but increased solute concentration in leaves of 36C-grown plants probably contributed to turgor maintenance.

Growth and Chemical Composition of Populus deltoides × nigra Grown in Field-grow Fabric Containers

Growth and chemical composition of popular (Populus deltoides × nigra, DN 69) grown in field-grow fabric containers (FGFC) was evaluated. Unrooted hardwood cuttings were grown in 0.6, 2.4, 6.0, and 14.0 L (0.2, 0.6, 1.6, and 3.7 actual gal) custom-made FGFC inserted in 3, 6, 12 and 24 L (#1,2,3 and 6 trade size) plastic nursery containers, resp. A 3.5 cm (1.4 in) layer of the same medium was placed under the between the FGFC and the walls of the nursery container. Each bag was filled with a medium of pine bark; spruce bark (3:1 by vol.). Control plants were grown in containers of all sizes without FGFC in the same medium. Plant growth increased with increasing container size. Root dry weight of plants grown in FGFC were 21% less than plants without FGFC. However, there was no difference in top growth between FGFC and control plants. Soluble sugars concentration was 7% higher in leaves of FGFC grown plants, but leaf N, P, and K concentrations were similar. Roots outside the FGFC contained more N, P, and K than roots inside the FGFC. Soluble sugars and starch concentrations were greater inside the FGFC than outside.