Among the trypsins we have the pa pain of the Papaw fruit (Carica Papaya), the bromelin of the Pine-apple, and the enzymes present in many germinating seeds, in the seedlings of several plants, and in other parts.
Observation of germinating seedlings makes it clear that somehow they have a perception of direction.
Any attempt to interfere with these directions, by placing the seedlings in abnormal positions, is frustrated by the seedlings themselves, which change their direction of growth by bringing about curvatures of the different parts of their axes, so that the root soon grows vertically downward again and the stem in the opposite direction.
Pythium, which causes the damping off of seedlings, reducing them to a putrid mass in a few hours, and Phytophthora, the agent of the potato disease.
With seedlings and tender plants, however, matters are frequently complicated by the onslaughts of Fungie.g.
The tree is a favourite with hares and rabbits, and the seedlings are apt to be destroyed by mice.
For new varieties the flowers should be fertilized with a view to combine, in the seedlings which result from the union, the desirable qualities of the parents.
These beetles, characterized by their skipping movements and enlarged hind femora, also attack the hop (Haltica concinna), the vine in America (Graptodera chalybea, Illig.), and numerous other species of plants, being specially harmful to seedlings and young growth.
Soaking the seed in strong-smelling substances, such as paraffin and turpentine, has been found efficacious, and in some districts paraffin sprayed over the seedlings has been practised with decided success.
After the seedlings appear, thinning is completed in usually three successive hoeings, the plants being watered after thinning, and subsequently at intervals of from twelve to fifteen days, until about the end of August when picking commences.
A state sugar experiment station is maintained at Audubon Park in New Orleans, its work embracing the development of seedlings, the improvement of cane varieties, the study of fungus diseases of the cane, the improvement of mill methods and the reconciliation of such methods (for example, the use of sulphur as a bleaching and clarifying agent) with the requirements of " pure food " laws.
Hevea brasiliensis was introduced to Ceylon and Singapore from seedlings raised at Kew from Brazilian seed, specially collected by Mr H.
The seedlings rapidly developed and in most places in which they were planted grew into large trees which furnished satisfactory latex when tapped in their sixth or seventh year.
Hevea seedlings were also introduced into India, but did not apparently succeed except in Burma and S.
Great care is necessary in attending to the watering of the young and delicate seedlings, which are ready for transplanting in from fifty to sixty days after sowing.
Seedlings should be protected from frost during the first winter.
The plants are raised from seedlings, and when six or seven weeks old they are transplanted in rows 4 to 6 ft.
The number of trees in this grove has been gradually diminishing, and as no young trees or seedlings occur, the grove will probably become extinct in course of time.
With respect to the production of hybrids, the genus is remarkable for its power of resisting the influence of foreign pollen, for the seedlings of any species, when crossed, generally resemble that which bears them.
Tulips are readily raised from seeds, and the seedlings when they first flower (after about 7 years cultivation) are of one colour - that is, they are self-coloured.
(The colour variation in the flowers of seedlings is discussed above.) Seeds are sown in.
The seeds are sown in April, on rich ground, which should not be too highly manured; the young larches are planted out when two years old, or sometimes transferred to a nursery bed to attain a larger size; but, like all conifers, they succeed best when planted young; on the mountains, the seedlings are usually put into a mere slit made in the ground by a spade with a triangular blade, the place being first cleared of any heath, bracken, or tall herbage that might smother the young tree; the plants should be from 3 to 4 ft.
In plantations made with this object, the seedlings are placed very close (from 12 to 2 ft.
The young seedlings are sometimes nibbled by the hare and rabbit; and on parts of the highland hills both bark and shoots are eaten in the winter by the roe-deer; larch woods should always be fenced in to keep out the hill-cattle, which will browse upon the shoots in spring.
Supposing seedlings to have been developed, it is found that a large number of them present considerable variations, some being especially robust, others peculiar in size or form.
The pricking out of seedlings in pots in the propagating pit is effected in a similar way.
Thus shallow square or oblong wooden boxes, made of light, inexpensive wood, are very useful for seedsowing, for pricking out seedlings, or for planting cuttings.
It is from having ample room that pricked out transplanted seedlings often make the finest plants.
Pythium is a semiaquatic form attacking seedlings which are too plentifully supplied with water; its hyphae penetrate the cell-walls and rapidly destroy the watery tissues of the living plant; then the fungus lives in the dead remains.
They are usually included in Oomycetes, but their simple structure, minute size, usually uniciliate zoospores, and their negative characters would justify their retention as a separate group. It contains less than 200 species, chiefly parasitic on or in algae and other water-plants or animals, of various kinds, or in other fungi, seedlings, pollen and higher plants.
Some forms cause damping off of seedlings - e.g.
The seedlings should then be 6 ins.
Deep are dug for each plant, and refilled loosely - then the seedlings are carefully placed in them.
For instance, the young shoots seen springing from the ground around an elm are not seedlings but root-shoots.
They germinate only in the second year after sowing; in the course of their first year the seedlings attain a height of 6 to 12 in.
The modern orange industry practically began with the introduction into Southern California in 1873 of two seedless orange trees from Brazil; from their stock have been developed by budding millions of trees bearing a seedless fruit known as the " Washington navel," which now holds first rank in American markets; other varieties, mainly seedlings, are of great but secondary importance.
The seedlings when large enough to handle are placed either singly in very small pots or several in a pot or shallow pan, and put in a bottom heat, in a moist atmosphere with a temperature from 60° to 70°.
Vast numbers of Scotch firs are raised in nurseries for artificial planting; the seed is sown in the spring, being just covered with earth, and the seedlings transplanted in the second year into rows for further culture, or taken direct from the seed-bed for final planting; sometimes the seed is sown where the trees are intended to grow.
If, on the other hand, the true seeds of any of our cultivated varieties are sown, the seedlings show very wide variations from one another and from the parents.
In this connexion it is very interesting to observe that Messrs Sutton of Reading find that the seedlings of many of the varieties of potato that occur spontaneously in different parts of America come quite true to type from seed.
When the seedlings are 2 or 3 in.
The vascular system of cycadean seedlings presents some features worthy of note; centripetal xylem occurs in the cotyledonary bundles associated with transfusion-tracheids.
When the seedlings make their appearance another field is prepared for transplanting.
Thus, De Vilmorin records the presence of turgid wheats among seedlings raised from a common wheat fertilized with the pollen of a hard variety, and spelt wheats among the descendants of a common crossed with a turgid wheat.