A tetraploid plant has four sets of chromosomes per cell a diploid has two sets which simply means tetraploid ryegrasses are more palatable for livestock. Stock prefer tetraploids over diploids if they have a choice and are more quickly and completely eaten by livestock. PGG Wrightson Seeds are specialists in tetraploid technology, breeding market leading cultivars since We offer a complete tetraploid portfolio of annual, Italian, short rotation, long rotation, and perennial ryegrasses, with a range of endophyte options.
These cultivars have built an impressive reputation with New Zealand farmers, due to their palatability, resilience, and animal performance benefits.
Perennial ryegrass has high sugar content, high digestibility and produces a high yield of good quality. Perennial ryegrass is particularly suitable for mixtures with white clover. Diploid varieties are — compared to tetraploid — distinguished by being more fine-leaved and dense in growth.
They are more resistant to damage by grazing cattle. The diploids have a higher dry-matter content. Tetraploid varieties are typically darker and more broad-leaved, and slightly higher yielding with higher sugar content, better winter hardiness, and more open growth.
The plant growth in height was measured with the help of a graduated rule, beginning at the substrate surface until the highest growth point, on the dates mentioned above. In the flow cytometry analysis plants from 83 seeds were evaluated, whereas four seeds, one of each rootstock of citrumelo 'Swingle', citrange 'Troyer' and citranges 'Fepagro C 13' and 'Fepagro C 37' produced a tetraploid and a diploid plant simultaneously in the same seed.
The ploidy level of these plants was confirmed as tetraploid Figure 1 by analyzing somatic cells from root ends. The presence of diploid and tetraploid plants in the same seed appears to be common in citrus and has already been described by Aleza et al. In the morphological evaluations of the diploid and tetraploid plants according to the morphological descriptor of the IBPGR Table 1 all the plants presented type 2 leaves, that is, trifoliate Table 2 and Figure 2.
Trifoliate leaves have already been described in the morphological characterization of the citrumelo 'Swingle' and citrange 'Troyer' rootstocks, while the characterization of this study for the citranges 'Fepagro C 13' and 'Fepagro C 37' confirms the results already expected, since the plants evaluated were obtained from the breeding with the P.
In terms of color, the diploid plants presented leaves with green coloring, while the tetraploids presented a more intense green, considered a darker green, besides presented more leathery leaves than the diploids Table 2. In this study, the differences observed in color and consistency of the leaves of the tetraploid plants corroborate the description made by Latado et al. The difference observed in the leaf coloring of the diploid and tetraploid plants Table 2 agrees with Machado et al.
According to Leechet et al. Therefore, this may be the factor responsible for a more intense coloring observed in the tetraploid plant leaves in this study Table 2. Regarding the characteristic of length of the petiole compared to the blade, all plants were short-petiolated, with a narrow and obovate shaped petiole. Regarding the blade shape, the leaves were classified as ellipsoids, with the exception of the tetraploid plant of the 'Fepagro C 13' rootstock, which was classified as orbiculate.
As for the format of the margin, all plants presented leaves with serrated edge Table 2. When comparing diploid and tetraploid plants, there were variations regarding petiole length and length and width of the leaf Table 3.
The highest values of petiole length were found in the diploid plants Table 3 , with the longest petiole length in diploid plants being 1. The longest petiole length in diploid plants was found in the 'Fepagro C37' with 2. In the overall average of rootstocks, there were significant statistical differences and the diploid plants presented longer petioles, averaging 1.
These results are consistent with those proposed by Frost and Soost , that the diploid plants present longer petioles than the polyploids. When analyzing the length of the leaves, in most evaluations the leaves of the diploid individuals were shorter than those of the tetraploids. In diploid plants, the lowest average length was 2. In the overall average there were significant statistical differences between diploids and tetraploids, where the tetraploid plants had a longer leaf length with a mean of 2.
Regarding the width of the blade of the central leaflet of the leaves, diploid plants showed smaller width than the tetraploids Table 3. In the overall average the tetraploid plants presented a central leaflet blade with a width of 1.
The largest length and width of leaves observed in tetraploid plants in this study Table 3 and Figure 2 agree with what has been described by Latado et al. The growth evaluations found variations in plant height between diploid and tetraploid plants, and the diploids were always higher. The greatest initial height in diploid plants was found in the 'Troyer' rootstock, with The lowest initial height in diploid plants was In this study, the results obtained with the height evaluations of diploid and tetraploid citrus plants over a year, allowed the observation that tetraploids presented a smaller and more compact form Figure 3 , agreeing with Cameron and Frost and Lee , that morphological characteristics that are different among plants with different levels of ploidy, while polyploid plants have a more compact form and reduced size when compared to diploid plants.
The results of this study are also consistent with data obtained by Allario et al. Frost and Soost highlighted that, regarding cytogenetics, the only variation between citrus autotetraploid plants and their diploid siblings is the duplicated number of chromosomes. However, according to these authors, regarding morphological and growth characters, the difference between diploid and tetraploids can easily be verified, since the tetraploid plants present slower growth, compacter shape, fewer and less vigorous sprouting.
According to Syvertsen et al. Therefore, the lower growth and the more compact shape of the tetraploid plants observed in this study Figure 3 agree with the affirmation of Frost and Soost that the distinction between diploids and tetraploids can be easily verified by analyzing morphological characters.
Citrus rootstocks should confer good characteristics to cultivate canopy, such as tolerance to drought and salinity, good quality and productivity of fruit Allario et al. In this study, differences in morphological characteristics between diploid and tetraploid plants were observed, such as differences in growth, whereas tetraploid plants were always smaller and more compact.
0コメント