Soil Study

Root Microbiome Engineering Improves Plant Growth Only a few published studies have looked at the effects of artificially selecting microbiomes. In their own labs, the authors--Ulrich Mueller of the University of Texas at Austin and Joel Sachs of the University of California, Riverside--have seen microbiome engineering to be successful with Arabidopsis (a close relative of cabbage and broccoli). In the Arabidopsis experiments, bacteria from the roots of the largest plants were harvested with a filter and given to other plants growing from seed. Over time, the plants, which were genetically identical and therefore could not evolve by themselves, grew better because of their evolved and improved microbiomes. "My hope is that others will become interested in optimizing methods in other systems," says Mueller. "For agricultural applications, I would start with artificial selection of root microbiomes in a greenhouse environment, using cash crops such as lettuce,...

Difference between Biennial and Perennial Plants Biennial plant completes its life cycle in two growing seasons. The first season’s growth is entirely vegetative, and is typically characterized by short, low internodes called rosettes.  In second season, it bolts, i.e. sends up a flowering stalk with extended internodes bearing flower and fruits. Root vegetables like carrots and beets; leafy vegetables like lettuce and cabbage; and others like onions are biennial in nature. Perennial plants grow for years, and most of them are woody. Their growth can be divided into juvenile and mature phases. During the first phase, the plant grows vegetatively for several years. In the second phase, reproduction starts, and vegetative and reproductive growth are concurrent. All of our fruit trees and ornamental shrubs and trees are perennial, and some herbaceous plants are also perennial. The above ground parts of such plants are killed in winter while the underground storage structu...

Side Grafting In side grafting vigorous stock shoots are selected. Fresh and mature scion sticks about 12-13 cm long are collected from a desired variety and their leaves are clipped off. A 2-3 year old stock tree planted in orchard rows is selected. At the base of the scion on one side a longitudinal cut of 5-8 cm is made, cutting away half of the girth at the base and thus making a wedge. An oblique cut is made in the stock at an angle of 20-30 degree and about 2.5 cm deep, and the scion is inserted in the cut portion and gently pushed down until it is fixed in the bark. The union is tied with waxed cotton tape and wrapped with polythene. After the graft sprouts, the polythene is removed. This method can be performed in both spring and autumn, but the maximum rate of 90% is achieved during spring.  

Bridge Grafting and T-Grafting Bridge Grafting It is practiced to save valuable trees with diseased or damaged trunks. To prepare the tree trunk for bridge grafting, the damaged part is trimmed back to healthy tissue by removing dead or torn bark from the affected parts.  Bridge grafting is best performed during early spring when the bark can be lifted easily. Scions of sufficient length to bridge over the damaged area are taken. One long slanting cut is made at each end of the scion, both cuts on the same side. A second cut is made on back side. The bark on both upper and lower sides of the wounded area is loosened as in bark grafting, and the scions are then inserted between the bark and wood of the stock and are nailed down. All cut surfaces are carefully coated with wax, and any sprouting on scion surface should be removed. Complete healing takes place in a few years. T-Grafting               ...

Tongue Grafting and Bark Grafting Tongue Grafting                                 The scion and rootstock are cut exactly in the same way as in splice grafting. To provide strength and exposure of greater cambial area for union, tongue shaped slits are then made in both scion and stock. The secondary slits are half the length of the original slanting cuts. The scion and stocks are brought together, firmly interlocking. The graft wounds are waxed over, with or without typing. Bark Grafting                                 Unlike in the cleft graft, the stub of the stock is not cut horizontally. Instead, several scions with their basal ends trimmed as wedges are inserted betwe...

Splice Grafting A slanting cut about 10 cm long is made at the basal end of the scion, which is placed on a corresponding cut made on the rootstock seedling at a height of 30-40 cm from ground level, and then tied together. The cambial areas of scion and stock should be in close contact; to achieve these both should be of the same thickness. The top of the plant down to the graft union is covered with a polythene bag, loosely tied at the basal end to prevent excessive transpiration. The union takes place within three weeks to three months, depending upon the plant species involved and the age and condition of scion and rootstock. Splice grafting has been employed in grafting mango in the Philippines and Brazil, and for some varieties of Apple.

Wedge or Cleft Grafting This method is generally used in the propagation of deciduous fruits and top working older trees of inferior varieties. Branches of the rootstock 1.25-5 cm thick or even larger are cut at the top, and a vertical split 5-8 cm deep id made in the center of the stub with a heavy chisel or knife. The split is kept apart until scion containing at least three buds is inserted. The basal end of the scion is cut into a long sloping wedge about 5 cm long. The side of the wedge which is to face outward is made slightly wider than the inside edge. One scion is inserted in each side of the split. After adjustments of the scion, the tool used to keep the split open is removed to allow the full pressure of the split stock to bear on the scions at the point where the cambium of stock and scion are in contact. No tying is usually needed; however, all the wounded surfaces are thoroughly waxed over. Cleft grafting is the most successful when in early spring when the buds...

There are following Methods of Grafting. Inarching or Approach Grafting Wedge or Cleft Grafting Splice Grafting Tongue Grafting and Bark Grafting Bridge Grafting and T-Grafting Side Grafting

Inarching or Approach Grafting Unlike other grafting operations, in inarching the scion is attached to the stock while it is still attached to the parent plant. Round the world, the method has been extensively used in the vegetative propagation of mango. The method involves potting healthy one-year- old seedling in earthen pots, which are usually 12 in deep and 8 in wide at the top. The earth ball along with root system is kept intact and placed in the pot. The unfilled space in the pot is then filled with a mixture of well- rotted manure and canal silt. The soil is firmly pressed around the earth ball and the transplanted seedlings are then watered. Potting of seedlings is usually done one month ahead of actual inarching operations. This allows sufficient time for the seedlings to set before grafting. Inarching can either be done in the spring months or in the rainy season. July and August are preferred over the spring season because after inarching operations in the spr...

Grafting A grafted plant is composed of two parts. The basal part which provides the roots system for anchorage and absorption of moisture and nutrients is called the rootstock.  The scion provides top and fruits bearing surface and synthesize food which is transported to other parts of the plant. Scion and root stock should be compatible and closely related belonging to the same genus. Grafting is a process by which a piece of scion is attached to a rootstock in such a way that the cambium of both scion and rootstock come in firm contact so that the new secondary tissue resulting from cambial cell division in the scion and rootstock is closely knitted. The stock usually influences the size and vigour of the tree and the scion the yield and quality of fruit it will bear. Grafting allows utilization of varying climatic, soil and biotic conditions with advantage. When a single bud is used as scion and inserted into the rootstock the method is called budding, whereas when a pie...