Root Morphological Development in Relation to Shoot Growth in Seedlings of Four Range Grasses

1991 ◽  
Vol 44 (4) ◽  
pp. 341 ◽  
Author(s):  
Lucrecia Aguirre ◽  
Douglas A. Johnson
1994 ◽  
Vol 24 (1) ◽  
pp. 61-70 ◽  
Author(s):  
Conor O'Reilly ◽  
J.N. Owens ◽  
J.T. Arnott ◽  
B.G. Dunsworth

Western hemlock (Tsugaheterophylla (Raf.) Sarg.) seedlings grown in two different container cavities that received four different dormancy induction treatments, short (SD) or long days (LD) in combination with moisture stress (D) or no stress (W) in the greenhouse, and lifted and placed in cold storage (November, January, or March), were planted on two adjacent coastal reforestation sites in British Columbia and monitored for survival and morphological development. Survival was greatest in seedlings grown in the larger cavities in the greenhouse, in seedlings lifted in March, and in seedlings not treated to moisture stress. Seedling shoots had more stem units on the southeast than the northwest site, but the amount varied with nursery treatment. Seedlings from the LD treatments produced more stem units during free growth and lammas growth than those from the SD treatment. Nevertheless, most shoot growth was predetermined in the buds during nursery culture, accounting for a minimum of 67% of the final number of stem units. Stem unit length (SUL) was longer in seedlings on the southeast site than on the northwest site for those treated to LD in the nursery. Seedlings treated to short days showed the reverse pattern (SDW) to this, or were unaffected by site (SDD). Shoots and needles were shortest for seedlings from the SDD treatment and for those lifted in November. Shoot growth was greatest for seedlings lifted in March and for those treated with LD, mainly owing to their longer SUL. Lammas growth was most frequent in seedlings from the smaller cavities, and in those from the November and March lifts.


1994 ◽  
Vol 24 (8) ◽  
pp. 1608-1616 ◽  
Author(s):  
P. Puttonen ◽  
J.T. Arnott

Yellow cypress (Chamaecyparisnootkatensis (D. Don) Spach) stecklings (rooted cuttings) were acclimated for approximately 8 weeks under one of the following photoperiod–temperature treatments: 18 h/10 °C, 18 h/20 °C, 9 h/10 °C, 9 h/20 °C followed by deacclimation in a common environment of 12 h/20 °C for approximately 6 weeks. During acclimation and deacclimation, steckling morphological development, net photosynthesis, transpiration and leaf conductance, and midday shoot water potential were measured. Hardiness was determined by freeze-induced electrolyte leakage. Shoot growth was reduced more by short photoperiods (9 h) than by cool temperature (10 °C) as were net photosynthesis, stomatal conductance, transpiration, and photosynthetic efficiency. Photoperiod-induced cold hardening of shoots and height growth cessation were reversible in warm temperatures (20 °C) and 12-h days, indicating that hardiness induction treatments had no lasting effects on the growth or cold hardiness of this tree species.


Weed Science ◽  
1970 ◽  
Vol 18 (6) ◽  
pp. 754-759 ◽  
Author(s):  
A. Rahman ◽  
R. Ashford

The selective action of α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine (trifluralin) for the control of green foxtail(Setaria viridis(L.) Beauv.) in wheat(Triticum aestivumL.) was studied. Seedlings of both species, especially in the early stage of growth, were particularly susceptible to herbicide applied in the region of the coleoptile node. Selective control with trifluralin was possible, however, because of the morphological differences between the seedlings of the two species. Thus, the sensitive coleoptilar node area of green foxtail was located at a depth of less than 1 cm from the soil surface regardless of planting depth. The coleoptile node of wheat remained closely associated with the caryopsis. When a protective band of untreated soil was used to separate the caryopses from a 5-cm band of surface soil containing 1.12 ppmw of trifluralin, the shoot growth of wheat was normal. Much lower rates of trifluralin effectively controlled green foxtail, as surface or subsurface placement of a 1.3-cm layer of soil containing 1.12 ppmw of chemical above the foxtail caryopses completely inhibited shoot development. In addition to the differences in morphological development between the two species, the fact that green foxtail was considerably more susceptible to trifluralin than wheat was considered as an important factor contributing to the selective control.


1967 ◽  
Vol 20 (3) ◽  
pp. 141 ◽  
Author(s):  
R. L. Dalrymple ◽  
Don D. Dwyer

Author(s):  
Yun Lu ◽  
David C. Joy

High resolution scanning electron microscopy (SEM) and energy dispersive x-ray analysis (EDXA) were performed to investigate microparticles in blended cements and their hydration products containing sodium-rich chemical wastes. The physical appearance of powder particles and the morphological development at different hydration stages were characterized by using high resolution SEM Hitachi S-900 and by SEM S-800 with a EDX spectrometer. Microparticles were dispersed on the sample holder and glued by 1% palomino solution. Hydrated bulk samples were dehydrated by acetone and mounted on the holder by silver paste. Both fracture surfaces and flat cutting sections of hydrating samples were prepared and examined. Some specimens were coated with an 3 nm thick Au-Pd or Cr layer to provide good conducting surfaces. For high resolution SEM S-900 observations the accelerating voltage of electrons was 1-2 KeV to protect the electron charging. Microchemical analyses were carried out by S800/EDS equipped with a LINK detector of take-off angle =40°.


Author(s):  
G. M. Hutchins ◽  
J. S. Gardner

Cytokinins are plant hormones that play a large and incompletely understood role in the life-cycle of plants. The goal of this study was to determine what roles cytokinins play in the morphological development of wheat. To achieve any real success in altering the development and growth of wheat, the cytokinins must be applied directly to the apical meristem, or spike of the plant. It is in this region that the plant cells are actively undergoing mitosis. Kinetin and Zeatin were the two cytokinins chosen for this experiment. Kinetin is an artificial hormone that was originally extracted from old or heated DNA. Kinetin is easily made from the reaction of adenine and furfuryl alcohol. Zeatin is a naturally occurring hormone found in corn, wheat, and many other plants.Chinese Spring Wheat (Triticum aestivum L.) was used for this experiment. Prior to planting, the seeds were germinated in a moist environment for 72 hours.


Fruits ◽  
2003 ◽  
Vol 58 (6) ◽  
pp. 345-356
Author(s):  
Edossa Etissa ◽  
Seifu G Mariam ◽  
H. Ravishanker

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