scholarly journals Vegetative and reproductive development of Costa Rican weedy rice compared with commercial rice (Oryza sativa)

2007 ◽  
Vol 25 (1) ◽  
pp. 13-23 ◽  
Author(s):  
E. Sánchez-Olquín ◽  
G. Arrieta-Espinoza ◽  
A.M. Espinoza Esquivel
Keyword(s):  
Reproductive Development ◽  
Costa Rican ◽  
Weedy Rice ◽  
Growth Stages ◽  
Rice Varieties ◽  
Growth Increase ◽  
Wide Range ◽  
Time Required ◽  
Reproductive Phases ◽  
Range Of Variation

The variability in the chronology of the vegetative and reproductive development of weedy rice complex has been little studied. However, a field trial was established to study the timing of growth stages of sixteen weedy rice morphotypes and five rice varieties of Costa Rica. Weedy rice presented a wide range of variation for all descriptors among and within morphotypes. Weedy rice was taller than the rice varieties during vegetative phase and showed a growth increase of 14-23 cm every two weeks. Six morphotypes emerged earlier than commercial rice varieties, but no differences where found between samples for the time required for starting tillering. Early emergence of weedy rice morphotypes was not associated with early flowering, thus no correlation was detected between the vegetative and reproductive phases. All weedy rice morphotypes reached anthesis and maturity earlier than the rice varieties. Nevertheless, varieties Setesa-9 and CR-5272 overlapped anthesis with eleven morphotypes and variety CR-4338 overlapped flowering with eight weedy rice morphotypes. In contrast, none of the morphotypes overlapped anthesis with varieties CR-1821 and CR-1113. The results obtained showed the competitive capacity of weedy rice and provided valuable information about flowering overlap between weedy rice morphotypes and rice varieties which will be useful in the design of gene flow studies among them.

Cold tolerance in rice varieties at different growth stages

2009 ◽  
Vol 60 (4) ◽  
pp. 328 ◽  
Author(s):  
C. Ye ◽  
S. Fukai ◽  
I. Godwin ◽  
R. Reinke ◽  
P. Snell ◽  
...  
Keyword(s):  
Low Temperature ◽  
Cold Tolerance ◽  
High Elevation ◽  
Temperature Tolerance ◽  
Seedling Stage ◽  
Growth Stages ◽  
Rice Varieties ◽  
Low Temperature Tolerance ◽  
Wide Range ◽  
Different Growth Stages

Low temperature is a common production constraint in rice cultivation in temperate zones and high-elevation environments, with the potential to affect growth and development from germination to grain filling. There is a wide range of genotype-based differences in cold tolerance among rice varieties, these differences often reflecting growth conditions in the place of origin, as well as breeding history. However, improving low temperature tolerance of varieties has been difficult, due to a lack of clarity of the genetic basis to low temperature tolerance for different growth stages of the rice plant. Seeds or plants of 17 rice varieties of different origins were exposed to low temperature during germination (15°C), seedling, booting, and flowering stages (18.5°C), to assess their cold tolerance at different growth stages. Low temperature at the germination stage reduced both the percentage and speed of germination. Varieties from China (B55, Banjiemang, and Lijianghegu) and Hungary (HSC55) were more tolerant of low temperature than other varieties. Most of the varieties showed moderate levels of low temperature tolerance during the seedling stage, the exceptions being some varieties from Australia (Pelde, YRL39, and YRM64) and Africa (WAB160 and WAB38), which were susceptible to low temperature at the seedling stage. Low temperature at booting and flowering stages reduced plant growth and caused a significant decline in spikelet fertility. Some varieties from China (B55, Bangjiemang, Lijiangheigu), Japan (Jyoudeki), the USA (M103, M104), and Australia (Quest) were tolerant or moderately tolerant, while the remaining varieties were susceptible or moderately susceptible to low temperature at booting and flowering stages. Three varieties from China (B55, Lijianghegu, Banjiemang) and one from Hungary (HSC55) showed consistent tolerance to low temperature at all growth stages. These varieties are potentially important gene donors for breeding and genetic studies. The cold tolerance of the 17 rice varieties assessed at different growth stages was correlated. Screening for cold tolerance during early growth stages can therefore potentially be an effective way for assessing cold tolerance in breeding programs.

Vernalization Responses of Jointed Goatgrass (Aegilops cylindrica), Wheat, and Wheat by Jointed Goatgrass Hybrid Plants

Weed Science ◽  
2008 ◽  
Vol 56 (4) ◽  
pp. 534-542 ◽  
Author(s):  
Lynn Fandrich ◽  
Carol A. Mallory-Smith ◽  
Robert S. Zemetra ◽  
Jennifer L. Hansen
Keyword(s):  
Winter Wheat ◽  
Spring Wheat ◽  
Reproductive Development ◽  
Growth Stages ◽  
Aegilops Cylindrica ◽  
Jointed Goatgrass ◽  
Hybrid Plants ◽  
Synchronous Development ◽  
The Difference ◽  
Reproductive Phases

To assess the risk of gene movement between winter wheat and jointed goatgrass, information about the reproductive development of jointed goatgrass, winter wheat, and related hybrid plants is required. Seedlings from five jointed goatgrass populations, winter wheat, spring wheat, and jointed goatgrass by wheat reciprocal hybrid plants were exposed to 4, 7, or 10 C temperatures for 0, 2, 4, 5, 6, 6.5, 7, or 8 wk. Vernalized seedlings were transferred to a greenhouse set to 30/18 C day/night temperatures and 16-h photoperiod. Growth stages on all plants were recorded twice a week. All spring wheat and spring wheat related hybrid plants reproduced (as measured by the first reproductive node) in the absence of vernalization. Plants of jointed goatgrass population A-R, winter wheat, and winter wheat related hybrids were unlikely to reproduce in the absence of vernalization. Plants of jointed goatgrass populations B-W, G-S, E-S, and F-W reproduced in the absence of vernalization, and the likelihood that these plants would reproduce was different from all other plants. Plants that entered their reproductive phases together were not in synchronous development at anthesis. Plants in these studies differentially passed through the reproductive phases between the first reproductive node and anthesis. Our results demonstrate that variation in vernalization response exists among several jointed goatgrass populations, and reveal that the reproductive behavior of vernalized jointed goatgrass plants at anthesis is delayed compared to vernalized winter wheat and related hybrid plants. Hybrid plants produced between spring wheat and jointed goatgrass were vernalization insensitive. We hypothesize that hybridization between wheat and jointed goatgrass occurs as a result of cross-pollination between the younger reproductive tillers of jointed goatgrass and older reproductive tillers of wheat. The use of an early maturing wheat cultivar may exploit the difference in reproductive development and reduce the risk of hybrid production.

Salinity tolerance in rice varieties at different growth stages

1988 ◽  
Vol 28 (3) ◽  
pp. 343 ◽  
Author(s):  
DP Heenan ◽  
LG Lewin ◽  
DW McCaffery
Keyword(s):  
Vegetative Growth ◽  
Reproductive Development ◽  
Dry Weight ◽  
Sodium Concentration ◽  
Growth Stages ◽  
Rice Varieties ◽  
Shoot Dry Weight ◽  
Matter Production ◽  
Linear Regressions ◽  
Different Growth Stages

The salt tolerance of several Australian and overseas rice varieties was studied at germination, early vegetative growth, and reproductive development in a temperature controlled glasshouse to determine the reliability of screening at any particular stage. At all 3 stages, varieties differed in their degree of tolerance, but the order of tolerance varied considerably between stages. Of the varieties used, the Australian long grain variety Pelde was tolerant for germination but most intolerant during early vegetative growth and reproductive development. The Japanese variety Somewake was intolerant during germination and vegetative growth but most tolerant during reproductive development. Linear regressions showed inverse relationships (r2 = 0.97-0.73) between sodium concentration in the shoots during early growth and shoot dry weight for most varieties. For Pelde, dry matter production was most closely related to potassium concentration in the shoots (r2 = 0.92).

scholarly journals Varied shoot growth in rice plants across different developmental stages under induced flooding

2021 ◽  
Vol 8 (3) ◽  
Author(s):  
Pratyasha Samanta ◽  
Abhra Chakrabarti ◽  
Narottam Dey
Keyword(s):  
Developmental Stages ◽  
Shoot Elongation ◽  
Leaf Sheath ◽  
Growth Stages ◽  
Internodal Length ◽  
Rice Varieties ◽  
Submergence Stress ◽  
Wide Range ◽  
Early Seedling ◽  
Sensitive Line

All the modern high yielding rice varieties precariously respond to flooding, although a number of landraces are tolerant to wide range of flooding with penalty of low yield. Stage-specific flood tolerance experiment was performed at three different conditions for three different growth stages from germination to vegetative stage for five such selected landraces, along with a flood-resistant quiescent variety (FR13A), a sensitive line (IR42), an improved cultivar (Swarna) and one Sub1 loci introgressed improved line (Swarna-Sub1). Different morpho-physiological traits at each stage were observed and genotypes were evaluated by these quantifiable traits to understand their underwater performance. All the studied landraces represented strong seed germination and faster coleoptile elongation than FR13A, Swarna and Swarna-Sub1 under water. At early seedling stage var. Kumrogarh embraced with highest number of seedlings with leaves and extended greater leaf portion above the water. Shoot elongation associated with internodal and petiole/blade elongation and well developed aerenchyma tissue facilitated vegetative tissues to survive. In this stage, Kumrogarh had highest plant height but Bakui had highest internodal length which indicated that kumrogarh might have the greater leaf sheath or blade elongation up to day 21 and also smaller increase (%) in air cavity formation at day 21 which made the stem to be upright devoid of lodging. All these results indicated that the studied landraces are the potential resources for submergence avoiding response for all the stages and should be elaborately investigated for future breeding programme. The rice line kumrogarh may be one of the potent traditional rice which can withstand all sorts of submergence by virtue of all the stage-specific attributes under submergence stress.

Microwaves: Application in Electron Microscopy

1990 ◽  
Vol 48 (3) ◽  
pp. 140-141
Author(s):  
Anthony S-Y Leong ◽  
David W Gove
Keyword(s):  
Electron Microscopy ◽  
Light Microscopy ◽  
Chemical Reactions ◽  
Electromagnetic Waves ◽  
Tissue Fixation ◽  
Primary Method ◽  
Dipolar Molecules ◽  
Wide Range ◽  
Time Required ◽  
Cryostat Sections

Microwaves (MW) are electromagnetic waves which are commonly generated at a frequency of 2.45 GHz. When dipolar molecules such as water, the polar side chains of proteins and other molecules with an uneven distribution of electrical charge are exposed to such non-ionizing radiation, they oscillate through 180° at a rate of 2,450 million cycles/s. This rapid kinetic movement results in accelerated chemical reactions and produces instantaneous heat. MWs have recently been applied to a wide range of procedures for light microscopy. MWs generated by domestic ovens have been used as a primary method of tissue fixation, it has been applied to the various stages of tissue processing as well as to a wide variety of staining procedures. This use of MWs has not only resulted in drastic reductions in the time required for tissue fixation, processing and staining, but have also produced better cytologic images in cryostat sections, and more importantly, have resulted in better preservation of cellular antigens.

TIME TO THE END OF PRIMARY CONSOLIDATION (EOP) OF SOFT CLAYEY SOILS: CONCERNING THE EFFECT OF ATTERBERG’S LIMIT AND CYCLIC LOADING HISTORY

2019 ◽  
Vol 128 (2B) ◽  
pp. 29-41
Author(s):  
Trần Thanh Nhàn
Keyword(s):  
Cyclic Loading ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Clayey Soils ◽  
Loading History ◽  
Cyclic Shear ◽  
Wide Range ◽  
Primary Consolidation ◽  
Time Required

In order to observe the end of primary consolidation (EOP) of cohesive soils with and without subjecting to cyclic loading, reconstituted specimens of clayey soils at various Atterberg’s limits were used for oedometer test at different loading increments and undrained cyclic shear test followed by drainage with various cyclic shear directions and a wide range of shear strain amplitudes. The pore water pressure and settlement of the soils were measured with time and the time to EOP was then determined by different methods. It is shown from observed results that the time to EOP determined by 3-t method agrees well with the time required for full dissipation of the pore water pressure and being considerably larger than those determined by Log Time method. These observations were then further evaluated in connection with effects of the Atterberg’s limit and the cyclic loading history.

A Leaf Bud Development Scale for Rabbiteye Blueberry

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 455f-456 ◽  
Author(s):  
D. Scott NeSmith ◽  
Gerard Krewer ◽  
Jeffrey G. Williamson
Keyword(s):  
Reproductive Development ◽  
Developmental Differences ◽  
Research Management ◽  
Growth Stages ◽  
Vaccinium Ashei ◽  
Bud Development ◽  
Dormant Bud ◽  
Mouse Ear ◽  
Highbush Blueberries ◽  
Winter Chilling

Crop vegetative and reproductive development are frequently divided into stages to describe progression of development. Such a description is useful in denoting developmental differences between cultivars, for making crop management decisions based on growth stages, and for clear communication among individuals concerned with research, management, and production of the crop. We have developed such a scale for leaf bud development in rabbiteye blueberry (Vaccinium ashei Reade). Our scale has six stages briefly described as follows: 1) dormant bud; 2) early green tip; 3) late green tip; 4) unfolding stage; 5) mouse-ear stage; 6) fully opened bud. Categorizing buds in this manner has proven useful in comparing rates of leaf development between cultivars and in response to winter chilling. The stages appear to be relevant to highbush blueberries (V. corymbosum) as well.

Evaluation and Avoidance of False Alarm by Controlling Rhine Water with Continuously Working Biotests

1994 ◽  
Vol 29 (3) ◽  
pp. 207-209 ◽  
Author(s):  
H. Puzicha
Keyword(s):  
Warning System ◽  
Point Sources ◽  
Trophic Levels ◽  
River Rhine ◽  
Wide Range ◽  
River Test ◽  
Continuous Working ◽  
Range Of Variation ◽  
Contaminant Load ◽  
Rhine Water

Effluents from point sources (industries, communities) and diffuse inputs introduce pollutants into the water of the river Rhine and cause a basic contaminant load. The aim is to establish a biological warning system to detect increased toxicity in addition to the already existing chemical-physical monitoring system. To cover a wide range of biocides, continuous working biotests at different trophic levels (bacteria, algae, mussels, water fleas, fishes) have been developed and proved. These are checked out for sensitivity against toxicants, reaction time, validity of data and practical handling under field conditions at the river. Test-specific appropriate methods are found to differentiate between the normal range of variation and true alarm signals.

Analysis and Reduction of the Waste in the Work Process Using Time Study Analysis: A Case Study

2014 ◽  
Vol 660 ◽  
pp. 971-975 ◽  
Author(s):  
Mohd Norzaim bin Che Ani ◽  
Siti Aisyah Binti Abdul Hamid
Keyword(s):  
Cycle Time ◽  
Lean Manufacturing ◽  
Value Added ◽  
Time Study ◽  
Study Approach ◽  
Root Cause ◽  
Wide Range ◽  
Unit Of Work ◽  
Time Required ◽  
The Impact

Time study is the process of observation which concerned with the determination of the amount of time required to perform a unit of work involves of internal, external and machine time elements. Originally, time study was first starting to be used in Europe since 1760s in manufacturing fields. It is the flexible technique in lean manufacturing and suitable for a wide range of situations. Time study approach that enable of reducing or minimizing ‘non-value added activities’ in the process cycle time which contribute to bottleneck time. The impact on improving process cycle time for organization that it was increasing the productivity and reduce cost. This project paper focusing on time study at selected processes with bottleneck time and identify the possible root cause which was contribute to high time required to perform a unit of work.

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