Agricultural problems of saline arable land in Pakistan

Abstract

Salinity represents a serious threat to irrigated arable land. It has been estimated that about one-third of the irrigated land of the world is now salt-affected. In addition, vast areas of potentially fertile land cannot be used for the cultivation of conventional crops because of an excessive salt content of the soil.Crop growth is not only depressed by excess salt but also by the poor quality of the structure of the saline soil. Under certain conditions chemical amendment (application of gypsum) may improve the physico-chemical quality of arable land but only locally and at high costs. For the arid and semi arid conditions in Pakistan it can be calculated that using the amount of water the river Indus transports through the flood plains, only a limited area can be properly irrigated and used for agriculture without salination. Therefore an extensive area of salt affected land will always remain and be abandoned by the farmers. During the last two decades biosaline research aims at cultivation of salt adapted plants on saline arable land.The perspective of conventional screening and breeding techniques to obtain salt tolerant crops is discussed. Also advanced biotechnological approaches (callus and cell culture, meristem culture, plant regeneration, and protoplast fusion) have improved the possibilities to increase salt tolerance in plants. Fodderbeet is a domesticated cultivar of the coastal halophyte Beta vulgaris. Cultivars of the fodder beet were found fairly salt tolerant and even improved growth of the leaves and beet was found on saline land in field trials as compared with non-saline land.Further field studies are being carried out to test the usefulness of this salt tolerant crop on salt affected land in Pakistan combined with other salt tolerant crops (Chenopods, grasses, legumes), to be used in rotation schemes. In addition, since the mechanism of salt tolerance is still incompletely understood, fundamental research is required to see how higher plants may grow well under saline conditions.