Number Of New Roots Research Articles

Perbandingan Kualitas Pot Hitam dan Softpot Terhadap Pertumbuhan Vegetatif Anggrek Dendrobium sonia ersakul

The aim of this research is to compare the quality of black pots and soft pots on the vegetative growth of the Dendrobium sonia ersakul orchid. The method used was perfect randomization with one treatment, namely black pot and soft pot. Data analysis used a two-way t-test at the 5% level. The results of the research show that using different types of pots can make a real difference to the parameters of plant height, length of shoots and number of new roots, but does not make a real difference to root length. The difference in the quality of the two pots is influenced by the level of water supply to the plant, plant drainage, and the level of oxygen absorption in the roots. Keywords: Dendrobium Orchid, Vegetative Growth, Black Pot, Softpot

Pengaruh Pemberian Variasi Konsentrasi Vitamin B1 (Thiamin HCl) Terhadap Pertumbuhan Fase Vegetatif Anggrek Dendrobium sonia

This study aims to determine the effect of varying concentrations of vitamin B1 on the growth of the vegetative phase of the Dendrobium sonia orchid. This research was carried out experimentally using a Completely Randomized Design (CRD) with 4 treatment levels, namely Growmore Fertilizer (2 gr/l) as a control and vitamin B1 concentration (1 ml/l, 2 ml/l, 3 ml/l) then each -Each treatment was repeated 5 times to get 20 plants, each treatment consisting of 5 plant samples. The parameters used are root length, number of new roots, shoot height and number of shoots. The data obtained was analyzed using the one way anova test. The results of the research showed that Dendrobium sonia orchids treated with varying concentrations of vitamin B1, the parameters of root length, number of shoots, shoot height and average number of shoots had vegetative growth that did not look much different. In conclusion, vitamin B1 has no significant effect on the vegetative growth of Dendrobium sonia orchids. Keywords: Dendrobium sonia, Vegetative Phase, Vitamin B1

Effectiveness of Eco Enzyme for Inducing Flower Growth in Dendrobium Sonia-ersakul Orchids

Orchid plants are ornamental plants with various shapes, colors, and sizes, exhibiting unique characteristics that make them a special attraction for enthusiasts of ornamental plants. Among them is the Dendrobium orchid, which belongs to the genus of orchids known for its diverse types and beauty. Enhancing the growth and quality of Dendrobium Sonia-ersakul orchid flowers can be achieved through proper fertilization. The fertilizer in this research is derived from liquid organic fertilizer, Eco Enzyme. This research aims to assess the impact of Eco Enzyme on the induction of flowering growth in Dendrobium orchids. This research was carried out at CV Candi Orchid, 17 Bukit Unggul Raya Street, Semarang, over three months, from May to July 2023. The research design employed in this research is the two-tailed t-test research method, which includes a control group and an experimental group treated with 0.2% Eco Enzyme. There were two combinations, with each treatment comprising six replicates. The measured variables included the number of roots, root length, buds, and panicles. The outcomes indicated that the application of Eco Enzyme led to a significant increase in the number of panicles compared to the control group. However, no significant differences were observed in root length, the number of new roots, or the number of buds when Eco Enzyme was applied.

Pengaruh Variasi Konsentrasi Indole Butyric Acid (IBA) Pada Anggrek (Dendrobium hybrid) Terhadap Survival dan Pertumbuhan Dalam Media Arang

One of the most popular types of orchids by the public is the Dendrobium Orchid. One of the functions of adding growth regulators is Indole Butyric Acid (IBA) which functions to accelerate root growth. The content possessed by IBA can cause additional roots under certain conditions. This study aims to determine the optimal variation of the concentration of the hormone Indole Butyric Acid (IBA) on the growth of Dendrobium hybrid orchids. Acclimatized Dendrodium hybrid seedlings were selected first, planted on charcoal media, and treated twice a week for two months using an IBA concentration of 0.25; 0.50; 0.75; and 1 ml/L. In this study, the optimal concentration of IBA with root length parameters was at a concentration of 1 ml/L with an average of 2.33. For a concentration of 0.75 ml/L with the parameter of the number of new roots having an average of 1.94 and the parameter of the number of leaves having an average of 1.85. Plant length with a concentration of 0.50 ml/L had an average of 2.56. The concentration of 0.25 ml/L with leaf length parameter has an average of 1.94 while the wet weight parameter has an average of 1.04. For the effect of giving IBA hormone on survival, the most optimal concentration was 0.75 ml/L with 91% live and 9% dead.

Spatial distribution and dynamics of cotton fine root under film-mulched drip irrigation

Fine roots distribution and dynamics (production, mortality, and longevity) significantly impact the crop soil ecosystems. However, the spatial distribution and dynamics of cotton (Gossypium hirsutum L.) fine roots under film-mulched drip irrigation are poorly understood. The present study aims to characterize these distributions and dynamics measured using a minirhizotron technique and the influence of soil conditions. The non-uniform distribution of soil moisture and salinity may lead to the differences of root length density (RLD) distribution. A clear decreased trend for the average RLD was observed in the shallow soil layer due to high localized salinity accumulated after brackish water irrigation. There existed a clear high soil moisture content strip at depth which may lead to a high RLD peak in the 95–100 cm soil layer. Average live root production was characterized by a very high rate during the initial growth stage followed by a decline after budding, which in turn was followed by a slight increase during boll opening. The average number of new roots was highest during the initial growth stages, decreasing after the budding stage. Thinner roots in the deep soil had shorter lifespans than those in shallow soil. Our study indicated that the minirhizotron technique can be used reliably as an in situ, non-destructive method for estimating cotton fine roots distribution and dynamics under film-mulched drip irrigation. To evaluate cotton fine root distribution and dynamics under film-mulched drip irrigation more accurately, a cotton root system architecture model could be parameterized in space and time based on the minirhizotron observations.

Perspectives on Drought Preconditioning Treatments With a Case Study Using Western Larch.

As the demand for drought hardy tree seedlings rises alongside global temperatures, there is a need to optimize nursery drought preconditioning methods to improve field performance of planted seedlings. This perspective article advocates for a more holistic approach to drought preconditioning research that considers the moderating role of plant developmental stage on the effects of drought preconditioning. We identify discrepancies in past studies of root growth potential (RGP) responses to drought preconditioning and highlight studies that suggest such discrepancies may result from inconsistencies among studies in the timing of drought preconditioning implementation. We then illustrate our perspective by presenting original research from an aeroponic RGP trial of 1st-year western larch (Larix occidentalis Nutt.) seedlings exposed to three soil moisture contents for 6months. We evaluated whether drought preconditioning could be used to increase the ratio of root: foliar tissue mass or enhance seedling physiological vigor during a subsequent growth period. Drought preconditioning was found to increase the ratio of root: foliar tissue mass and enhance seedling physiological vigor. Specifically, soil moisture content related negatively with new root biomass, positively with new foliar biomass, and negatively with the length and number of new roots (p<0.001). Meanwhile, the mass of lateral root production following drought preconditioning, but prior to aeroponic growth, correlated weakly to the mass, count, and length of new roots produced during aeroponic growth. We propose that evaluating the importance of the timing of drought preconditioning treatments constitutes an important research frontier in plant science.

Fungal endophytes from medicinal plant Bletilla striata (Thunb.) Reichb. F. promote the host plant growth and phenolic accumulation

Endophytic fungi are capable of increasing the growth and secondary metabolite production of medicinal plants in an ecofriendly and sustainable manner. Although these responses have been demonstrated in many plant species, they are not well understood in the medicinal plant Bletilla striata (Thunb.) Reichb.F.. Co-culture of B.striata with three endofungal isolates was carried out to evaluate the effects of endophytic fungal interaction on the plant growth and accumulation of phenols. The plant growth-promoting traits of isolated fungi were investigated, and the isolates had the ability to produce indole-3-acetic acid (IAA), siderophore and cellulolytic enzyme. The fungal strain Byssochlamys spectabilis 1-N2 co-cultured with plantlets of B. striata significantly increased certain growth properties, including shoot length by 71.40%, pseudobulbs dry weight by 52.58%, number of new roots by 5.25-fold, pseudobulbs diameter by 30.94% and improved the total phenolic content of the medicinal part by 25.41%. The fungal polysaccharide elicitor prepared from B.spectabilis 1-N2 mycelium also altered the accumulation of total phenolic content at different time points. Polysaccharide elicitor treatment significantly enhanced the accumulation of nitric oxide (NO) and salicylic acid (SA), which are involved in the plant defence response and significantly upregulated the activities of phenylalanine ammonia lyase (PAL), cinnamate-4-hydroxylase (C4H) and tyrosine ammonia lyase (TAL). The findings of this study contribute to our understanding of B. striata and endophytic fungi interactions and provide vital information for the use of endophytic fungi to improve plant growth and active component accumulation in B.striata cultivation.

Rooting ability of rice seedlings increases with higher soluble sugar content from exposure to light.

Rooting ability of rice seedling for mechanical transplanting has a large impact on grain yield. This study explored the relationship between endogenous soluble sugar content and rooting ability of rice seedlings. We placed 15-day-old rice seedlings in controlled environment cabinets with stable light and sampled after 0, 3, 6, 9, 12, and 24 hours of light to measure their soluble sugar content, nitrate content, starch content, soluble protein content and rooting ability. The soluble sugar content of the rice seedlings before rooting increased rapidly from 65.1 mg g-1 to 126.3 mg g-1 in the first 9 hours of light and then tended to stabilize; however, few significant changes in the other physiological indices were detected. With the light exposure time increasing from 3 hours to 12 hours, the rooting ability measured with fresh weight, dry weight, total length, and number of new roots increased by 91.7%, 120.0%, 60.6% and 30.3%, respectively. Rooting ability was related more closely to soluble sugar content than to nitrate-nitrogen content of rice seedlings before rooting and their correlation coefficients were 0.8582-0.8684 and 0.7045-0.7882, respectively. The stepwise regression analysis revealed that the soluble sugar content before rooting explained 73.6%-75.4% of the variance, and the nitrate-nitrogen content explained an additional 7.3%-14.2% of the variance in rooting ability, indicating that compared with nitrate-nitrogen content, soluble sugar content of rice seedlings before rooting was more dominant in affecting rooting ability. This study provides direct evidence of the relationship between the rooting ability and endogenous soluble sugar content of rice seedlings.

Chitosan Oligosaccharide Addition to Buddhist Pine (Podocarpus macrophyllus (Thunb) Sweet) under Drought: Reponses in Ecophysiology and δ13C Abundance

Climate warming induces the necessity to increase the drought resistance of shade-obligate juvenile trees in sub-tropical forests. Chitosan oligosaccharide (COS) is a biopolymer derived from the marine resource that has attracted accumulative attention to induce and promote a plant’s resistance to abiotic stress. Buddhist pine (Podocarpus mascrophyllus (Thunb)Sweet) seedlings were cultured as the model material whose natural distribution in sub-tropical areas of China has suffered severe summer drought events in the last 113 years. A split-block design was conducted with a simulated drought event (drought vs. irrigated control), the COS addition, and two samplings at the ends of drought and re-watered treatments. The COS addition increased the resistance to drought by inducing a starch allocation towards roots where δ13C abundance and antioxidant enzyme activities were upregulated. The COS addition can promote biomass allocation to roots and increase the number of new roots. The COS addition to drought-treated Buddhist pine seedlings resulted in robust diameter growth. Therefore, COS is an available polymer to promote the resistance of Buddhist pine to drought. More work is suggested to clarify the dose of COS addition that can induce a prominent response of biomass accumulation and carbohydrate metabolism.

Effectiveness Test of Orchid Mycorrhizal Isolate (Ceratorhiza and Trichoderma) Indonesia and Its Role as a Biofertilizer

Aim: The existence of Orchid Mycorrhizal Fungi (OMF) has a role to stimulate growth and support the supply of orchid nutrition as a biofertilizer agent. This study aimed to determine the association of mycorrhizal with Phalaenopsis amabilis (L.) Blume which was carried out through the effectiveness test of two Indonesian orchid mycorrhizal isolates i.e. Ceratorhiza and Trichoderma.&#x0D; Study Design: This study consisted of 4 treatments. Each treatment was repeated 3 times, each repetition of 5 plantlets, so that the total plantlet used was 60.&#x0D; Place and Duration of Study: Laboratory of Plant Biotechnology, Department of Biology, Universitas Gadjah Mada, Indonesia, between June 2017 and April 2018.&#x0D; Methodology: The method of inoculating orchid mycorrhizal by placing a plantlet in a petri dish containing orchid mycorrhizal for 1, 2, 3, and 4 days. Then plantlets are grown on sterile moss growing media and acclimatized in a greenhouse. Observation of each treatment is carried out every day for the next month. Observation variables include the number of initial and final roots, the number of live and dead roots, and the number of living and dead plants.&#x0D; Results: The results of the orchid mycorrhizal induction test showed that the Ceratorhiza inoculation treatment showed a fluctuation in the mean increase in the number of final roots, live roots, dead roots, and dead plantlets that were higher than the Trichoderma inoculation treatment. The results also showed that the best inoculation time on Ceratorhiza and Trichoderma was day 3 and 4. The adaptation process had the effect of increasing the number of dead roots in weeks 1 and 2. The adaptation process stopped at the beginning of week 4 with the number of new roots appearing a lot.&#x0D; Conclusion: Orchid mycorrhizal Ceratorhiza shows the value of effectiveness test compared with Trichoderma. The results of this study are expected to be basic information in efforts to cultivate natural orchids in Indonesia.

Applying Dickson Quality Index, Chlorophyll Fluorescence, and Leaf Area Index for Assessing Plant Quality of Pentas lanceolata

Plant quality greatly relates to the seedling vigor (SV), survival and growth of plants after transplantation. The objective of this study was to use the nondestructive measurements of chlorophyll fluorescence (ChlF) and leaf area index (LAI) as SV indices for star cluster (Pentas lanceolata). Plants were grown in potting soil under nature sunlight for 90 d. A total of 13 morphological and physiological parameters were selected for measurements. Among them, root growth potential (RGP) was the best predictor for SV in all tested plants. Plants were separated into 5 RGP groups based on the number of new roots, and remaining parameters were also separated into those same levels. The trends and rates of increase from levels 1 to 5 in Dickson quality index (DQI), LAI, total dry mass, and ChlF were all similar to the RGP index. Although RGP and DQI are frequently used as indices for SV, these measurements are time-consuming and require sample destruction. Consistent and strongly high correlations were observed among DQI, LAI, and ChlF, demonstrating the applicability of these indices for measuring SV in star cluster. The measurements of LAI and ChlF were predicted using multiple variables from validation datasets, and showed novel and useful parameters for examining the SV of star cluster.

Saline-alkaline tolerance of hygrophilous plant species during their asexual propagation and continued growth stages

This study determined the saline-alkaline tolerance of seven hygrophilous plant species during their asexual reproduction and continued growth stages. Indicators of asexual reproduction capacities (e.g., number of new buds/seedlings) and growth potential (e.g., total biomass, chlorophyll content index, number and length of new roots), as well as the Na+ and K+ concentrations and Na+/K+ ratios were obtained in tested plant species exposed in five alkaline salt treatments (NaHCO3) ranging from 0.3 to 20 dS/m during the 30 day experiment. The following results were observed: 1) excessive NaHCO3 (especially at a salinity level of EC ≥ 10 dS/m) seriously inhibited the capacity of asexual reproduction and continued growth; 2) the number of new buds/seedlings was significantly (P < 0.05) and positively correlated with the number of new roots of plants, while the number of new buds/seedlings was significantly (P < 0.05) and negatively correlated with the total biomass of plants; and 3) species-specific salt-tolerance strategies were observed, i.e., the entry and compartmentalization of Na+ was controlled, and a low Na+/K+ ratios in different parts of plants was maintained. In general, common reed (Phragmites australis), giant reed (Arundo donax), bulrush (Scirpus validus), and fishscale bamboo (Phyllostachys heteroclada) exhibited better saline-alkaline tolerance during asexual reproduction and continued growth under moderate saline-alkaline conditions. These species are recommended as potential plant species for restoring degraded saline-alkaline wetlands.

Root Dynamics of Peach Replant Tolerant and Susceptible Rootstocks in Soilswith Different Cropping History

Replant disease (RD) is a major constraint for the establishment of economically viable tree fruit production systems. The use of tolerant rootstocks is considered the most cost-effective and long-term sustainable option to manage RD. The present study examines root production and lifespan of a replant tolerant and susceptible peach rootstock in a replant and non-replant soil. RD susceptible rootstock genotype Lovell and RD tolerant rootstock genotype Viking were established in a replant and non-replant site. Aboveground growth was determined by measuring the tree-trunk cross sectional area annually, and belowground root dynamics were tracked during a 2-year period using minirhizotron technology. Viking trees were significantly larger than Lovell in the replant site only. No significant differences were observed on the number of new roots produced by the two rootstocks in the replant or non-replant sites. In the replant site, roots of Viking remained white for a longer period of time, had higher AMF colonization, and second order roots had longer lifespans than those of Lovell rootstock; however no differences were observed between rootstocks in the non-replant site. Future research on identification of host defense mechanisms is needed for the development of tools that will support and accelerate breeding of resistant rootstocks.

Genotypic variations in root traits of wheat varieties at phytomer level

The aims of this study were to investigate genotypic variations in root traits at phytomer level of wheat varieties and for recommending a few root traits as selection parameters in future breeding programs. Two separate experiments were conducted to measure their root traits for hydroponically grown wheat plants. In Experiment 1, main axis length, root hair density and diameter differed from phytomer to phytomer at 60 days after sowing for two varieties, Shotabdi and Sonalika. Density of first order laterals at their axis of origin, dry weights of roots and shoots and root:shoot ratio varied significantly among 8 varieties. In Experiment 2, number of root bearing phytomer, total number of adventitious roots, main axis length at root bearing phytomer 1 and 2 (youngest roots were the reference point and numbered as phytomer 1), length of first order laterals at phytomer 3, root hair density and dry weights of roots and shoots were significantly different among varieties. PC1 (principal component 1) resulted in significant variation among varieties for number of live leaves, new roots appeared, number of root bearing phytomer, total number of adventitious roots, root dry weight and shoot dry weight. PC2 yielded significant difference among varieties for live leaves, main axes length at phytomer 1 &amp; 2, number of new roots, root hair density and diameter. Selection of varieties based on main axes length at the youngest phytomer &amp; root hair density per unit surface area along with dry weights of roots and shoots could be recommended for future breeding program as these four parameters consistently resulted in significant variation among varieties. DOI: http://dx.doi.org/10.3329/jbau.v12i1.21238 J. Bangladesh Agril. Univ. 12(1): 45-54, June 2014

Effect of wood chip application on root growth of oak seedling and weed control in northern Iran

It was hypothesized that wood chips can serve as a mulch to improve the growth of young trees by facilitating the development of their root systems, inhibiting weed germination, and suppressing weed growth. The present study was carried out in Ghorogh Nursery, Golestan Northern Iran, in order to investigate the impact of wood chips application on root growth of oak (Quercus castaneifolia) seedlings and control of weed. A three centimeter wood chip layer was used on the soil surface as the mulch treatment with bare soil as the control. The number of new roots, the length of exciting roots and the density of weeds were measured after 5 and 12 weeks. Results showed that wood chip application had significant positive effect on the length of excising roots after 5 and 12 weeks compared with control seedlings. Also, weeds were reduced to near zero levels in treated plot. Our findings suggested that wood chip layer on the soil surface in the nursery can conserve soil moisture and prevent nutrient leaching from the rooting zone as well as diminish weed growth which consequently lead to production of high quality seedling.

Influence of Plantlet Age and Different Soilless Culture on Acclimatization of Stemona curtisii Hook.f.

The aim of this experiment was to study the optimal age of Stemona curtisii plantlets for acclimatization. The in vitro shoots of S. curtisii were cultured on Murashige and Skoog solid medium supplemented with 1 mg L-1 naphthalene acetic acid to induce roots. Then, the plantlets from in vitro culture of 4, 8 and 12 week-old were transferred into the soil and their survival rate during the acclimatization process in the greenhouse was investigated. It was found that the 8 week-old plantlets had the highest survival rate of 80%. However, to enhance the survival rate of these plantlets, a soilless culture technique as a possible approach for the acclimatization was considered. Eight week-old plantlets were transferred into either, soil, a hydroponic system (nutrient film technique), coconut fiber or sand. The plantlets which were cultivated in coconut fiber or hydroponic culture showed 100% survival rate with the highest average number of new roots per plant. However, the mean root length of the plantlets grown in hydroponic system was significantly higher than that grown in coconut fiber.

Pythium species and cold storage affect the root growth potential and survival of loblolly (Pinus taeda L.) and slash pine (Pinus elliottii Engelm.) seedlings

When bareroot Southern pine (Pinus) seedlings are lifted in the fall and placed in cold storage for more than one week, survival is generally lower than when seedlings are lifted and stored during the winter. The combination of root wounding at the time of lifting with the presence of Pythium in the soil, the cool, moist conditions in cold storage encourage Pythium growth that results in seedling mortality after outplanting. Loblolly pine (Pinus taeda L.) and slash pine (Pinus elliottii Engelm.) seedlings were inoculated with either Pythium dimorphum orPythium irregulare, cold stored for 3 weeks, and placed in a hydroponic system (aerated aquariums). Seedling Root growth potential (RGP was measured as the number, length, volume, surface area, and diameter of new roots and survival was recorded 4 months after outplanting. Both Pythium species reduced the number of new roots and root length, root surface area, and root volume in slash pine. P. irregulare reduced the number of new roots, root length, and root surface area andP. dimorphum reduced the number of new roots on loblolly pine. Although, P. irregulare lowered RGP, it did not reduce loblolly pine survival. In contrast, P. irregulare inoculation did reduce the survival of slash pine seedlings after outplanting. Key words: Pythium dimorphum, Pythium irregular, root collar diameter; bareroot.

Root growth dynamics of Aleppo pine (Pinus halepensis Mill.) seedlings in relation to shoot elongation, plant size and tissue nitrogen concentration

Large and high nitrogen (N) concentration seedlings frequently have higher survival and growth in Mediterranean forest plantations than seedlings with the opposite traits, which has been linked to the production of deeper and larger root systems in the former type of seedlings. This study assessed the influence of seedling size and N concentration on root growth dynamics and its relation to shoot elongation in Aleppo pine (Pinus halepensis Mill.) seedlings. We cultivated seedlings that differed in size and tissue N concentration that were subsequently transplanted into transparent methacrylate tubes in the field. The number of roots, root depth, and the root and shoot elongation rate (length increase per unit time) were periodically measured for 10 weeks. At the end of the study, we also measured the twig water potential (ψ) and the mass of plant organs. New root mass at the end of the study increased with seedling size, which was linked to the production of a greater number of new roots of lower specific length rather than to higher elongation rate of individual roots. Neither plant size nor N concentration affected root depth. New root mass per leaf mass unit, shoot elongation rate, and pre-dawn ψ were reduced with reduction in seedling size, while mid-day ψ and the root relative growth rate were not affected by seedling size. N concentration had an additive effect on plant size on root growth but its overall effect was less important than seedling size. Shoot and roots had an antagonistic elongation pattern through time in small seedlings, indicating that the growth of both organs depressed each other and that they competed for the same resources. Antagonism between shoot and root elongation decreased with plant size, disappearing in large and medium seedlings, and it was independent of seedling N concentration. We conclude that root and shoot growth but not rooting depth increased with plant size and tissue N concentration in Aleppo pine seedlings. Since production of new roots is critical for the establishment of planted seedlings, higher absolute root growth in large seedlings may increase their transplanting performance relative to small seedlings. The lack of antagonism between root and shoot growth in large seedlings suggests that these plants can provide resources to sustain simultaneous growth of both organs.

FINE ROOTS GROWTH AND LONGEVITY IN A HIGH-DENSITY PEAR ORCHARD ON QUINCE C ROOTSTOCK AS AFFECTED BY NITROGEN SUPPLY

Root development of quince C (Cydonia oblonga L.) genotype used as a rootstock for pear (Pyrus communis L.), cultivar Abbe Fetel was studied during 2004 and 2005 with the minirhizotron technique. The orchard, located near Bologna (Po Valley, Northern Italy), was planted in February 2003 and spaced 3.8 x 0.9 m. Besides control (unfertilized) trees there were trees fertigated with urea-N and others with an organic soluble N fertilizer. When provided, nitrogen rates amounted to 48 kg N ha -1 year -1 . Fine roots were observed with minirhizotrons of 70 cm depth inserted into the soil at 30 cm from tree trunk; root images were taken and analyzed by WinRHIZO Tron MF software. We observed a higher number of new roots in 2004 than in 2005, but in both years root birth mainly occurred in late winter-spring and, with less intensity, in autumn. The distribution of new roots along the soil profile differed in N-fertilized and unfertilized trees. Root longevity was unaffected by N supply but changed over time, being lowest in spring (often less than 20 days) and highest in autumn (often > 100 days). Most (68%) white roots observed at the end of November 2004 were still visible in February 2005 as white roots, a feature that should be favourable for nutrient uptake as soon as spring growth occurs.

Growth and Physiological Traits Associated with Drought Survival and Post-drought Recovery in Perennial Turfgrass Species

The objective of this study was to determine physiological traits for drought survival and post-drought recovery upon re-watering in two C3 perennial grass species, kentucky bluegrass [KBG (Poa pratensis)] and perennial ryegrass [PRG (Lolium perenne)]. Plants were maintained well watered or exposed to drought stress by withholding irrigation and were then re-watered in a growth chamber. KBG had significantly higher grass quality and leaf photochemical efficiency, and lower electrolyte leakage than PRG during 20 days of drought. After 7 days of re-watering, drought-damaged leaves were rehydrated to the control level in KBG, but could not fully recover in PRG. KBG produced a greater number of new roots, while PRG had more rapid elongation of new roots after 16 days of re-watering. Superior drought tolerance in KBG was associated with osmotic adjustment, higher cell wall elasticity, and lower relative water content at zero turgor. Osmotic adjustment, cell wall elasticity, and cell membrane stability could play important roles in leaf desiccation tolerance and drought survival in perennial grass species. In addition, post-drought recovery of leaf hydration level and physiological activity could be associated with the accumulation of carbohydrates in leaves and rhizomes during drought stress and new root production after re-watering.