Commonly thought of as a series of letters that make up a 'word' there is a distinction between acronyms and shorthand. Online enthusiasts are learning that shorthand are in fact called acronyms, but this is incorrect. The difference between acronyms and shorthand is that with acronyms, you pronounce the letters as a new word for example, 'FUBAR' is pronounced 'foo-bar' and 'RADAR' is pronounced 'ray-dar'.
In contrast, shorthand pronunciations are like an initialism a set of initials in which you say the letters one-by-one for example, 'ESP' is an initialism for 'extra sensory perception' whereas 'esp. The online practice is to refer to shorthand, initialisms, or abbreviations as acronyms. The majority of the expressions you see above are not acronyms, but rather shorthand used while text messaging or IMing.
There are several terms to describe different kinds of jargon including anacronym , backronym , weather acronyms , city acronyms , leetspeak and textonyms. The tissues corresponded to adaxial epidermis, palisade parenchyma, bundle sheath cells, vascular bundles, and abaxial epidermis. The epidermis is uniseriate, with the adaxial face thicker than the abaxial face Figure 1 C and D. Similar results were reported by Ferreira et al. Figure 1 Leaf blade thickness A , homogeneous parenchyma B , adaxial epidermis C , and abaxial epidermis D of Amaranthus hybridus leaf grown at different soil moisture levels.
The same as for the leaf blade, there was increase in the thickness of parenchyma, adaxial epidermis, and abaxial epidermis with increase of water deficit Figures 1 B, C and D. It is worth noting that the parenchyma of branches, roots, and leaves are important water reservoirs Zweifel, et al. The leaves of A. We also observed a marked reduction in the proportion of vascular bundles in the leaf blade of A. In contrast to the other tissues of A. The decrease in the proportion of the different tissues is possibly due to the decrease in cell size in response to water stress Lukovik, , Zhang et al.
On the other hand, the increase in thickness of the parenchyma is a characteristic that has been related to tolerance to osmotic Rajabpoor et al. Figure 2 Proportion of adaxial epidermis A , proportion homogeneous parenchyma B , abaxial epidermis C , bundle sheath cells D , and vascular bundle E of Amaranthus hybridus leaf grown at different soil moisture levels. Figure 2 Cont. Proportion of adaxial epidermis A , proportion homogeneous parenchyma B , abaxial epidermis C , bundle sheath cells D , and vascular bundle E of Amaranthus hybridus leaf grown at different soil moisture levels.
Thus, the increase in leaf thickness is the result of an increase in thickness of epidermis and parenchyma, and the increase of parenchyma was more pronounced, in terms of proportion. The increase in parenchyma thickness seems to be associated with the increase of both photosynthetic efficiency and water use efficiency Kulkarni et al. CO 2 is transported to bundle sheath cells where it is definitly captured in the Calvin-Benson cycle.
Interestingly, the water restriction caused a proportional increase in the parenchyma and a decrease in vascular tissues, including the sheath Figure 2B and D.
The reduction in the conduction capacity is, unlike that observed for the parenchyma, an indicator of lack of tolerance to water stress. The quantitative anatomy study of B. Blade leaf thickness of B. The internal tissues of B. However, the vascular bundle sheath showed no significant variation with decrease in soil moisture Figure 6 D , which is similar to what is observed in plants with low tolerance to water stress Zhang et al. As discussed earlier, the reduction in thickness of leaf tissues is possibly related to the decrease in cell size.
However, in the case of B. Figure 5 Leaf blade thickness A , adaxial epidermis B , homogeneous parenchyma C , vascular bundle diameter D , and abaxial epidermis thickness E of leaves of Brachiaria brizantha grown at different soil moisture levels. Figure 5 Cont. Leaf blade thickness A , adaxial epidermis B , homogeneous parenchyma C , vascular bundle diameter D , and abaxial epidermis thickness E of leaves of Brachiaria brizantha grown at different soil moisture levels.
Figure 6 Proportion of adaxial epidermis A , bundle sheath cells B , homogeneous parenchyma C , vascular bundles D , and abaxial epidermis E of leaves of Brachiaria brizantha grown at different soil moisture levels. Figure 6 Cont. Proportion of adaxial epidermis A , bundle sheath cells B , homogeneous parenchyma C , vascular bundles D , and abaxial epidermis E of leaves of Brachiaria brizantha grown at different soil moisture levels.
The water deficit caused an increment in the proportion of adaxial epidermis of B. However, the proportion of parenchyma increased and the proportion of bundle sheath cells decreased with soil moisture reduction Figures 6 B and C. It is interesting that the thickness of epidermal cells on the adaxial surface of B.
Considering that the bulliform cells were measured together with the epidermis, we can infer that there was a reduction in the proportion and thickness of the epidermal cells, but an increase in the proportion of bulliform cells in response to water deficiency. Bulliform cells have thin walls and thin or no cuticles, thus they lose water by transpiration more quickly than other epidermal cells.
As the turgor pressure decreases in the bulliform cells, the maintenance of the turgor pressure in the cells on the abaxial lower side causes leaves to roll up. Figures 3 and 4 show the visual effect of the water deficit in the two species evaluated, with the increase in leaf thickness of A. According to Shao et al. Thus, the reduction of vascular bundle size in stressed plants, as observed in B. Changes caused by water stress are related to other stress factors, such as high temperatures and excess solar radiation.
Coffee plants subjected to high radiation intensity, without shading, for example, had greater leaf blade thickness, which is typical of sun leaves, responding primarily to water limitation due to excess temperature Nascimento et al. These characteristics tend to minimize heating by increasing the thickness of the chlorophyll parenchyma, with the purpose of absorbing, channeling and dispersing the light, not interfering with the leaf activities Batista et al. Different soil moisture levels affected weed species differently, causing changes in both the thickness of the tissues analyzed and their proportions.
Stapf e B. Revista Brasileira de Zootecnia, Journal of Experimental Botany, Journal of Experimental Botany , Planta Daninha, Cao KF Leaf anatomy and chlorophyll content of 12 woody species in contrasting light conditions in a Bornean heath forest. Canadian Journal of Botany, Functional Plant Biology, Annals of Botany, Planta Daninha , A review. Agronomy and Sustainable Development, Flora,
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