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На сайте с 16.05.07 Сообщения: 7007 В дневниках: 16
Добавлено: Ср Июн 09, 2021 17:08
Here I will want to explain my views on why the number of new cultivars of Crassula ovata is limited.
I will consider only 3 possible Crassula ovata that are stable under non-stressful conditions. These are regular Crassula Ovata with white flowers (1), Crassula Ovata 'Pink Beauty' (2) and Crassula Ovata 'Hummel's Sunset' (3). The composition of pigments and their number in the leaf cells of these Crassula ovata depends on their genetics. And this same genetics determines their difference.
I don't have exact literature data, but I am sure that the ordinary Crassula ovata genetically has the most chloroplasts (N1) and the least chromoplasts (M1). 'Pink Beauty' and 'Hummel's Sunset' have fewer chloroplasts (N2, N3) and more chromoplasts (M2, M3) that differ in composition. N1 is the chloroplast number in ordinary ovata, M1 - the chromoplast number in ordinary ovata, N2 - the chloroplast number in 'Pink Beauty', M2 - the chromoplast number in 'Pink Beauty' and N3 - the chloroplast number in 'Hummel's Sunset', M3 - the chromoplast number in 'Hummel's Sunset'. So, N1 > N2 ≈ N3 and M1 < M2 ≈ M3. The chromoplast composition of 1 and 2 may be are the same.
In the variegated cultivars obtained from these three ovatas, the amount of chloroplasts changes. But the genetic predisposition to the formation of certain chromoplasts in their variegatas persists.
Thanks to my opponents, I changed my mind about the formation of minor cultivars. Yes, with a lack of nitrogen nutrition, the formation of chloroplasts decreases. But the genetic ratio of the pigments in the leaves is preserved. And a larger number of chloroplasts will not allow a stable reduction in the size of the regular ovata leaves. So Lutea has enough pigments of chloroplast its minor Crosby's Compact variegata to be stable. The ratio of pigments also allows to get stable Crosby's Compact with very small leaves. While in the regular ovata, the growth rate simply decreases with a strong lack of nitrogen.
Alba, White Nights, Tricolor can not have minor forms because they do not have enough of the major and accessory pigments of photosynthesis. Solana, Lemon-Lime and Mikaery Bijin as mediovariegated and so having more chloroplasts can form minors, but such minors may be are not very stable.
Two cultivars, Hummel's Ghost и Hojawon Sunshine, require special explanation. They have the same leaf pigment composition and are both margin variegated. But chlorophyll-free cells in Hummel's Ghost are usually not able to synthesize pigments. And Hojawon Sunshine chlorophyll-free cells in contrast Hummel's Ghost synthesize pink pigments under light with low energy. Then these pigments promote the chloroplast formation in light under suitable conditions. Therefore, it should not be kept in the light with low energy and fertilized with nitrogen, so as not to stimulate the formation of chloroplasts to preserve the variegation.
Also, Lutea and Hummel's Sunset do not yet have mediovariegated cultivars, because their chlorophyll-free cells should not have and should not be able to synthesize pigments.
Последний раз редактировалось: ard (Пт Июн 18, 2021 16:48), всего редактировалось 2 раза