What are the methods for cultivating mango grafted rootstock seedlings?
How should large mango trees be fertilized scientifically? Please advise on fertilizing bearing mango trees. The principle should be to reasonably adjust the contradiction between vegetative growth and reproductive growth. It is necessary both to promote flowering and fruiting in the current year and control excessive summer shoot growth, and to promote the flushing and robust growth of autumn shoots, laying a good foundation for continued high yields the following year. Fertilization...
How is the best way to cultivate mango grafted rootstock seedlings? How should the rootstock seedlings be managed?A single seed of a monoembryonic mango variety produces only one seedling, while a polyembryonic variety can germinate and grow into multiple seedlings. A monoembryonic seed has only one embryo (the sexual embryo), which is large, and the single seedling that develops is strong; a polyembryonic seed has multiple embryos, which are smaller, and the multiple seedlings that develop are weaker. Therefore, in the past it was emphasized that monoembryonic varieties should be used as rootstock. However, rootstock uniformity is very important for improving mango yield and quality. Monoembryonic seedlings are sexual seedlings, and their growth performance varies greatly. The huge differences in growth and yield among different plants in an orchard are very likely caused by the rootstock. Therefore, after trials, seeds of polyembryonic varieties should be selected for cultivating rootstock seedlings. In the past, native mangoes with smaller fruit, less flesh, and poorer quality but plump, well-filled embryos were often recommended as rootstock. These native mangoes are mostly monoembryonic and grow vigorously; for the above reasons, they are not ideal as rootstock. As for polyembryonic varieties suitable for use as rootstock, they still need to be determined through trials on grafting compatibility, adaptability, and high-quality, high-yield performance.
Seedlings grown from seed are mainly used as rootstock or for breeding trials. The seeds used to cultivate seedlings grown from seed should come from the same variety and be collected from mature fruit; the seeds should be plump, disease-free, and insect-free. They should be extracted and sown as quickly as possible, because mango embryos are sensitive to water loss, and once dried, their germination capacity rapidly decreases. The seeds should have the fibrous skin and membranous layer removed, be soaked in a 0.1% potassium permanganate solution for 1 minute, taken out and air-dried, and then sown. The sowing medium is best medium-coarse river sand or vermiculite, with a sand bed thickness of 30 cm.
If it is a seedbed that has already been used, spray it thoroughly with a 1% formalin aqueous solution, cover it with plastic film for 24 hours to sterilize, then air it for 24 hours to dissipate the odor completely. The embryo can also be kept moist in a dark place to allow the embryo bud to sprout before sowing. When sowing, place the embryo flat; for monoembryonic seeds, make the embryo bud face the same direction, arrange them closely, with a row spacing of 15 cm. After sowing, cover with a 2 cm thick layer of river sand or vermiculite. If plastic film is not used to retain moisture, then when temperatures are high and air humidity is low, water must be applied daily. If film is used for shade and moisture retention, water once every 3-5 days, just enough to prevent drying. In Guangzhou, when sown between June and October, seedlings can emerge in 15-20 days, and are generally transplanted to the nursery field when they have 3-5 red leaves. Each polyembryonic seed can be separated into 3-4 seedlings; large and small seedlings should be graded slightly, and weak seedlings should be discarded. Monoembryonic seedlings can be transplanted a little later.
To cultivate high-quality nursery stock, it is best to use nursery bags at least 30-40 cm long and holding at least 3 kg of soil to cultivate rootstock seedlings for grafting. Because mango has few fibrous roots, bag cultivation helps ensure survival after transplanting. When cultivating seedlings in a nursery field, choose relatively clayey soil so that soil clumps are easily retained when lifting the seedlings. At transplanting, part of the main root must be cut off, leaving about 10 cm, or the main root should be coiled to encourage lateral root development. The soil in nursery bags can be slightly sandy, but because fertilizing is less convenient than in the field, sufficient fully decomposed organic fertilizer should be mixed in to ensure good root development. After transplanting, continue shading until the leaves have fully turned color, and give full sunlight only after the branches have matured. Monoembryonic seeds can also be sown directly into nursery bags.
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