Infection of adventitious roots of Agrostis palustris by Pythium species at different temperature regimes

1994 ◽  
Vol 72 (3) ◽  
pp. 378-383 ◽  
Author(s):  
Clinton F. Hodges ◽  
Douglas A. Campbell
Keyword(s):  
Low Temperatures ◽  
Adventitious Roots ◽  
Root Hairs ◽  
Dry Weight ◽  
Agrostis Palustris ◽  
Pythium Species ◽  
Root Tips ◽  
Pythium Arrhenomanes ◽  
Temperature Regimes ◽  
Disease Complexes

Pathogenicity of several isolates of Pythium species to the adventitious roots of Agrostis palustris was evaluated at high (35:24, light:dark) and low (24:13 °C, light:dark) temperature regimes. Isolates of P. graminicola–arrhenomanes, P. rostratum, P. torulosum, P. vanterpoolii, and one unclassified species were evaluated. All isolates of all species infected roots. Some isolates of P. graminicola–arrhenomanes (PGA-5), P. torulosum (PT-1, PT-2, PT-3, PT-5), P. vanterpoolii (PV-1), and an unclassified species (UP-1) infected roots and decreased dry weight at both the high and low temperature regimes. Other isolates of P. graminicola–arrhenomanes (PGA-1, PGA-2, PGA-4, PGA-6, PGA-7) and P. torulosum (PT-4) infected roots and decreased dry weight only at the high temperatures. Isolate PGA-7 of P. graminicola–arrhenomanes also stimulated plant growth at low temperatures. The remaining isolates of P. graminicola–arrhenomanes (PGA-3), P. rostratum (PR-1), and P. vanterpoolii (PV-2) infected roots and decreased dry weight only at the low temperatures. Infection of roots was limited to root hairs, root tips, and epidermal and cortical tissues. The observations are discussed relative to the function of Pythium species as minor root pathogens and their potential function in disease complexes. Key words: disease complexes, infection, minor pathogens, pathogenesis, pathogenicity, Pythium arrhenomanes, P. graminicola, P. graminicola–arrhenomanes, P. rostratum, P. torulosum, P. vanterpoolii.

scholarly journals (198) Growth and Development of Watermelon Plants Grafted onto Citrullus Rootstocks Selected for Disease Resistance at Two Temperature Regimes

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1053E-1054
Author(s):  
Yun-Chan Huh ◽  
Du-Hyun Kim ◽  
Sang-Gyu Lee ◽  
Kyoung-Sub Park ◽  
Dong-Kum Park ◽  
...  
Keyword(s):  
Plant Growth ◽  
Leaf Area ◽  
Low Temperatures ◽  
Dry Weight ◽  
Total Leaf Area ◽  
Relative Growth ◽  
Shoot Dry Weight ◽  
Temperature Regimes ◽  
Reduced Rate ◽  
Two Temperature

Growth response of `Sambok Honey' watermelon grafted onto different rootstocks, including four Citrullus rootstocks and three other cucurbitaceous rootstocks, was evaluated at low and normal temperature regimes. Marked reduction in plant growth rate was observed in plants grown at low temperatures as compared to those grown at normal or optimal temperatures. Relative growth reduction rates were 40% to 48% for vine length, 39% to 51% for total leaf area, 37% to 60% for shoot fresh weight, and 50% to 79% for shoot dry weight, respectively. Watermelon rootstock PI 482322 showed comparable plant growth as the most popular rootstock (Shintozwa pumpkin) even at low temperatures. `Sambok Honey' watermelon grafted onto watermelon hybrids `PI 271969 × PI 296341' and `PI 271769 × Calhoun Gray', showed comparable plant growth as FR Dantos bottle gourd rootstock. Index of growth ability at low temperature (IGALT), which was calculated on the basis of reduced rate of vine length, dry weight, and leaf area, was comparatively high in C. martinezii, Shintozwa, PI 482322, and `PI 271769 × PI 296341' rootstocks (50% or higher) and lowest in own-rooted `Sambok Honey' or in watermelon plants on `Knight' rootstock. Watermelon hybrids `PI 271969 × PI 296341' and `PI 271769 × Calhoun Gray' exhibited better or at least comparable growth at low temperatures as compared to `FR Dantos', thus confirming the feasibility of using watermelon rootstocks even in winter greenhouse conditions.

Effects of Growing Wheat in Hypoxic Nutrient Solutions and of Subsequent Transfer to Aerated Solutions. I. Growth and Carbohydrate Status of Shoots and Roots

1988 ◽  
Vol 15 (4) ◽  
pp. 585 ◽  
Author(s):  
EG Barrett-Lennard ◽  
PD Leighton ◽  
F Buwalda ◽  
J Gibbs ◽  
W Armstrong ◽  
...  
Keyword(s):  
Dry Weight ◽  
Triticum Aestivum L ◽  
Seminal Root ◽  
Platinum Electrodes ◽  
Root Tips ◽  
Seminal Roots ◽  
Crown Roots ◽  
Carbohydrate Status ◽  
Nutrient Solutions ◽  
Oxygen Concentrations

This paper evaluates the effects of hypoxia (imposed by flushing N2 gas through the nutrient solution) on the growth and carbohydrate status of wheat (Triticum aestivum L.), and the reversibility of these effects once aeration is resumed. Plants were transferred to hypoxic nutrient solutions (containing 0.003 mol O2 m-3) at the early tillering stage, when they had 3-4 leaves, well developed seminal roots, and a few crown roots. Hypoxia for 10-14 days had little adverse effect on shoot growth, whereas the seminal roots stopped growing, i.e. elongating and increasing in dry weight; in contrast, the crown roots elongated to a maximum of 9 cm and continued to increase in dry weight. Hypoxia increased the porosity of crown roots 2-3-fold compared with those grown under aerated conditions; in contrast, the porosity of seminal roots was unaffected. Oxygen concentrations in the gas filled pores of hypoxic crown roots (65 mm or longer) were estimated from measurements of radial oxygen loss using cylindrical platinum electrodes. Oxygen concentrations in the root tips were substantially lower than the critical oxygen pressures required for maximum respiration. Further, both oxygen concentrations in root tips and rates of root elongation were higher in shorter than in longer roots. Plants grown in hypoxic nutrient solutions had substantially higher sugar concentrations in shoots and roots than plants grown in aerated solutions. Sugars were not deficient in hypoxic roots since concentrations over a diurnal cycle remained higher than in aerated roots in both the bulk of the seminal and crown roots, and in the tips of the crown roots. Furthermore, tips of seminal roots had similar sugar concentrations when exposed to either aerated or hypoxic solutions. Hypoxia presumably killed seminal root apices, since the seminal axes did not resume elongation once aeration was restored. In contrast, crown roots resumed elongation when aeration was resumed. Although seminal root tips were moribund, the bulk of the seminal root was still alive. Following the transfer to aerated solutions, there was a rapid increase in the dry weight of both crown and seminal roots, in the latter case due to the proliferation of laterals.

Comparison of Green Foxtail (Setaria viridis) and Wild Oat (Avena fatua) Growth, Development, and Competitiveness under Three Temperature Regimes

Weed Science ◽  
1993 ◽  
Vol 41 (3) ◽  
pp. 369-378 ◽  
Author(s):  
David A. Wall
Keyword(s):  
Leaf Area ◽  
Dry Weight ◽  
Mature Seed ◽  
Wild Oat ◽  
Replacement Series ◽  
Relative Growth ◽  
Temperature Regimes ◽  
Green Foxtail ◽  
Increasing Temperature ◽  
Series Study

In a replacement series study, barley was more competitive than green foxtail and wild oat at 28/22 and 22/16 C. Wild oat was more competitive with green foxtail at 22/16 C than at 28/22 C. Maximum green foxtail dry weight and leaf area was produced at 28/22 C. As temperature increased, maximum dry weight and leaf area occurred earlier during plant growth. Similarly, maximum wild oat leaf area occurred earlier with increasing temperature, but the greatest leaf area was observed at 16/10 C. Leaf area ratio (LAR) and relative growth rate (RGR) of wild oat did not differ markedly between temperature regimes. Green foxtail LAR was higher while RGR was lower at 16/10 C than at 22/16 or 28/22 C. Under the 16/10 C regime green foxtail produced little mature seed. Greatest seed numbers were produced at 28/22 C. Wild oat produced mature seed under all temperature regimes with the greatest seed numbers produced at 22/16 C.

Effects of Elevated Temperature and Reduced Water Uptake on Enzymes of Starch Synthesis in Developing Wheat Grains

1990 ◽  
Vol 17 (4) ◽  
pp. 431 ◽  
Author(s):  
CY Caley ◽  
CM Duffus ◽  
B Jeffcoat
Keyword(s):  
Elevated Temperatures ◽  
Starch Content ◽  
Starch Synthesis ◽  
Dry Weight ◽  
Endosperm Development ◽  
Starch Synthase ◽  
Temperature Regimes ◽  
Endosperm Starch ◽  
Rate Limiting ◽  
Reduced Water

The mechanism of temperature regulation of endosperm development has been investigated by studying the effects of two temperature regimes on starch deposition and starch synthase activity during grain development in two cultivars of wheat. Most of the starch synthase activity was present throughout development as the granule-bound form using ADPglucose as the principal substrate. That starch synthase may be a rate-limiting enzyme for accumulation of starch, and hence dry weight, is suggested by: (1) rates are proportionately less in the cultivar with the lower final endosperm dry weight; (2) at elevated temperatures when starch content and dry weight are reduced, starch synthase activity falls; (3) the rate of starch deposition calculated to be possible from measured rates of starch synthase activity is close to the observed rate of starch deposition. On the other hand, it was concluded that it is not lack of starch synthase activity that causes termination of starch deposition, since activity is maintained well after starch deposition has ceased. Using the same two wheat cultivars, grown as detached ears in liquid culture, the effects of reduced endosperm water content, induced by the presence of polyethylene glycol in the culture medium, were investigated. Endosperm starch synthase activity was unaffected but ADPglucose pyrophosphorylase activity was greatly reduced, suggesting a possible role in the termination of starch synthesis.

scholarly journals Changes in soluble carbohydrates during storage of Caesalpinia echinata LAM. (Brazilwood) seeds, an endangered leguminous tree from the Brazilian Atlantic Forest

2006 ◽  
Vol 66 (2b) ◽  
pp. 739-745 ◽  
Author(s):  
I. S. Garcia ◽  
A. Souza ◽  
C. J. Barbedo ◽  
S. M. C. Dietrich ◽  
R. C. L. Figueiredo-Ribeiro
Keyword(s):  
Low Temperatures ◽  
Soluble Sugars ◽  
Dry Weight ◽  
Soluble Carbohydrates ◽  
Leguminous Tree ◽  
Neutral Sugars ◽  
Main Tendency ◽  
Low Levels ◽  
Caesalpinia Echinata ◽  
Seed Storability

Caesalpinia echinata seeds stored in laboratory environmental conditions lose their viability in one month whilst under low temperatures germination is maintained for 18 months of storage. These seeds are tolerant to desiccation, keeping their viability up to 0.08 gH2O.gDW-1. Since soluble carbohydrates are believed to be involved with desiccation tolerance and seed storability, the aim of this work is to analyze the content and composition of soluble carbohydrates in C. echinata seeds during storage in paper bags (PB) and glass flasks (GF) at laboratory room (RT) and cool (CT) temperatures. In freshly harvested seeds, total soluble carbohydrates comprised approximately 10% of the dry weight, decreasing to ca. 8% over 18 months of storage at RT. In seeds stored at CT, sugars varied differently decreasing initially and being restored at the end of the analysis period. The main neutral sugars in seeds from all treatments were sucrose, fructose and glucose. Raffinose and stachyose were present as traces. Free myo-inositol and other cyclitols were also detected. The main tendency observed was the variation in levels of both glucose and fructose in relation to sucrose, the highest levels of monosaccharides which were found in seeds stored at CT. The values of glucose and fructose were practically constant in seeds stored in paper bags for 18 months at CT, decreasing consistently in the other treatments, mainly at RT. Sucrose contents remained relatively stable. Changes in soluble sugars during storage suggest that the loss of germinability of seeds of C. echinata could be associated with low levels of glucose and fructose in relation to sucrose.

scholarly journals Interactive effect of AM fungi with Trichoderma viride and Pseudomonas fluorescens on growth and yield of broccoli

2013 ◽  
Vol 49 (No. 3) ◽  
pp. 137-145 ◽  
Author(s):  
A. Tanwar ◽  
A. Aggarwal ◽  
S. Kaushish ◽  
S. Chauhan
Keyword(s):  
Pseudomonas Fluorescens ◽  
Glomus Intraradices ◽  
Interactive Effect ◽  
Trichoderma Viride ◽  
Am Fungi ◽  
Dry Weight ◽  
Growth And Yield ◽  
Vegetable Crops ◽  
Fresh Weight ◽  
Root Tips

Most of the vegetable crops are known to depend upon arbuscular mycorrhizal fungal (AM) symbiosis for growth and development, since AM fungi provide nutrients and water in exchange for photosynthates.  The influences of AM fungi (Glomus intraradices (G) and Acaulospora laevis (A)) with Trichoderma viride (T) and Pseudomonas fluorescens (P) alone and in combinations on growth, mycorrhization, chlorophyll content, nutrient uptakes, and yield of broccoli plants were studied in pot culture under glasshouse conditions. The obtained results demonstrated that the single inoculation of broccoli plants with T. viride significantly increased the above ground fresh weight, root length, chlorophyll b, head diameter, root phosphorus, and shoot nitrogen in comparison to uninoculated control plants. On the other hand, consortium of G+A+T+P significantly increased plant height, above ground dry weight, root fresh weight, chlorophyll a, head fresh weight, and root nitrogen content. Similarly, G+T showed maximum leaf area, and P alone showed maximum uptake of shoot phosphorus. Whereas when P was supplied along with T, early flowering was recorded. AM fungal colonisation was negligible and only root tips were found infected in G or A treated plants which confirms low dependency of broccoli on AM fungi.  

scholarly journals Histological Observation of Primary and Secondary Aerenchyma Formation in Adventitious Roots of Syzygium kunstleri (King) Bahadur and R.C.Gaur Grown in Hypoxic Medium

Forests ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 137 ◽  
Author(s):  
Hong-Duck Sou ◽  
Masaya Masumori ◽  
Hiroyuki Kurokochi ◽  
Takeshi Tange
Keyword(s):  
Formation Process ◽  
Rainy Season ◽  
Adventitious Roots ◽  
Root Tip ◽  
Histological Observation ◽  
Root Tips ◽  
Aerenchyma Formation

Trees growing in wetlands develop adventitious roots from the trunk during the rainy season and adapt to the flooded environment by forming primary (schizogenous or lysigenous) and secondary aerenchyma in the roots. Therefore, it is necessary to clarify the formation process of each type of aerenchyma in these adventitious roots. In this study, saplings of Syzygium kunstleri (King) Bahadur and R.C.Gaur were grown under four different treatments, and a total of 12 adventitious roots generated from trunks were used to clarify the distribution of each aerenchyma type in the roots using light or epi-florescence microscopy. Schizogenous aerenchyma was observed in the root tips where the root color was white or light brown, whereas lysigenous aerenchyma was found at some distance from the root tip where the root color gradually changed from light to dark brown. The secondary aerenchyma and periderm were observed in dark brown parts near the root base. None or only one layer of phellem cells was detected in the white roots near the root tip, but dark brown roots near the root base had at least three layers of phellem cells. Considering these results, oxygen transportation may occur between primary and secondary aerenchyma at the point where two or more layers of phellem cells are formed.

scholarly journals Germination test of Eucalyptus phaeotricha seeds

2018 ◽  
Vol 22 (9) ◽  
pp. 653-657 ◽  
Author(s):  
Carlos E. Affonso ◽  
Givanildo Z. da Silva ◽  
Tatiane S. Jeromini ◽  
Cibele C. Martins
Keyword(s):  
Dry Weight ◽  
Water Volume ◽  
Conduction Time ◽  
Germination Test ◽  
Randomized Design ◽  
Temperature Regimes ◽  
Seed Analysis ◽  
Completely Randomized Design ◽  
Mean Time ◽  
Temperature Conduction

ABSTRACT The rules for seed analysis do not have recommendations for conducting the germination test of Eucalyptus phaeotricha seeds. Thus, the aim of this study was to determine the best substrate, temperature, conduction time, and substrate moistening level for the germination test of E. phaeotricha seeds. First count of germination, germination, germination speed index and mean time of germination were evaluated. The first experiment was carried out in a completely randomized design, in a factorial scheme (6 x 2), corresponding to six temperature regimes (15, 20, 25, 30, 35 °C and 20-30 °C) and two substrates (paper and sand) with four replicates, and the means were compared by Tukey test at 0.05 probability level. In the second experiment, the germination test was installed with the most favorable substrate and temperature identified in the previous step, evaluating substrate moistening levels equivalent to 1.0, 1.5, 2.0, 2.5 and 3.0 times the dry weight of the substrate; due to the quantitative nature of the treatments, the data were subjected to regression analysis and curve fitting. The germination test of E. phaeotricha seeds should be conducted at 30 °C on paper, moistened with a water volume of 2.2 times the dry weight of the paper, with initial and final counts at 6 and 14 days after sowing, respectively.

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