What methods are used to reduce water loss in agriculture?

Ensuring the availability of water and its dissolved nutrients is a challenge to growing our crops. Historically, the approach of farmers has been to grow crops adapted to the local environment (e.g., heavy rainfall for rice) or adapt the environment for the plant (irrigation). With our changing climate resulting in droughts, a new approach—adapting the plant’s genetic ability to the environment—has begun. The HARDY gene, described in Investigating Life: Improving Water-Use Efficiency in Rice, confers adaptation to drought in rice plants by upregulating the expression of clusters of genes involved in water-use efficiency, the ratio of plant biomass produced to water transpired. This is largely achieved through increased leaf thickness, with more mesophyll cells resulting in increased photosynthesis, as well as increased root growth, for greater uptake of water from the soil. The HARDY gene acts during development of leaves and roots, which you will recall happens throughout the life of the plant.

Future directions

Sorghum bicolor is an important grain crop worldwide, grown for human food, animal feed, and as a source for biofuels. It is especially valuable because it is both drought- and heat-tolerant, and so is important in hot, dry regions in Africa and South America. At the University of Illinois, scientists are trying to improve the water-use efficiency of sorghum by reducing transpiration in two ways: reduction of leaf stomata and shifting more photosynthesis to lower leaves, which are nearer to the ground and thus surrounded by humid air. Thousands of varieties of sorghum are stored in “seed banks.” Samples of these seeds will be germinated and grown in the search for the two desired phenotypes. In addition, a deliberate molecular approach using transgenic plants will be attempted. It is hoped that the result will be a crop even better adapted to make the best use of limited water.