Bio-techniques for improvement of qualitative and quantitative traits in walnut (Juglans regia)

Abstract

Walnut, Juglans regia (L.) is an economically significant plant for its immense nutritive and economic value. The breeding character of walnut has lent it a wide diversity in genetic characteristics. The principal vegetative and common traditional agronomic traits together with biochemical characterization i.e., karyotyping and isoenzyme expression have been the early research methods. However, these techniques are time-consuming and susceptible to the environmental variations. Literature is meager in the distribution, applied applications in general and the use of agriculture biotechnology in particular in case of walnut plants. The bio-techniques like molecular markers are adequate in number and there is little or no diversity in the method employed for research on walnuts. Despite basic research method, the organization of information, its retrieval and presentation structures, form elaboration experienced immense advancement via molecular markers such as RFLP, ISSR, RAPD AFLP, SSR and SNP. This appraisal in its first part provides detailed information regarding the present scenario of data on biogeographical distribution, health benefits of walnut worldwide and current applications in the agroforestry management, biochemical evaluations and applied uses of a walnut tree which is relevant for both basic and applied research. The review in its second part sheds light on the application of sophisticated agricultural biotechnology techniques such as use of molecular markers to evaluate, realize the full potential of walnut for increasing its quality, quantity and for its sustainable production which cannot be obtained through usual breeding techniques to meet the demands of a projected world population.