Recent development in the propagation of tropical and subtropical fruit crops by cutting

Many plants of horticultural interest are now propagated commercially by cuttings, since it is the easiest and most convenient method of vegetative propagation. Secondly, as the plants develop and grown on its own root system, the complex stock-scion relationship that exist in a graft can be avoided. However, the greatest disadvantage of this method is that some plants do not readily form roots on cuttings and the benefits derived from using desirable root stocks cannot be exploited. There is a wide variability among different plant species in their ability to root. There are certain tropical and sub-tropical fruit species (e.g., grape, lime, lemon) which root easily on cuttings, whereas certain other plants (e.g., guava, litchi, mango, avocado, jackfruit) produce root only when some manipulative treatments are given; but in still others rooting is not possible even with the help of the treatments. Although, propagation of tropical and subtropical fruits through cutting is the least expensive method of vegetative propagation, its success is still limited. However, the root initiating hormones can induce early and uniform rooting. Apart from auxin, a number of non-auxinic chemicals such as indoles, phenols, growth retardants and ethylene producing chemicals also influence rooting of cutting. Eventually, it is the hormonal balance, temperature, rainfall, humidity, nature of media and light that collectively decide the status of regeneration of roots in cutting. Pre-conditioning treatments such as girdling, blanching, etiolation of shoots have been shown to induce roots in some difficult-to-root tropical and subtropical fruit plants. Many researchers have successfully developed the protocol for propagation of a large number of tropical and subtropical fruits including papaya by cutting. This paper briefly discussed the technology available for propagation of tropical and subtropical fruit crops by cutting.