Prospects of Improving Photosynthesis for Increased Crop Productivity

Abstract

One purpose of photosynthesis research may be to obtain results which can be used in relation to plant breeding for increased productivity. Questions which can be posed relate to what is known about the relationship between photosynthesis and crop yield, can this knowledge be applied in order to improve yields, and do the techniques exist which may be used to implement such improvements? It is conventional to view productivity of plant crop systems in terms of the harvested yield per unit land area per annum or growing season; values explessed in terms of tonnes per hectare per annum are convenient. In the case of crops produced as a source of food, as fibre, for paper pulp, timber or chemicals, the economic yield represents only a part of the total biomass produced. On the other hand where crops are produced as a source of fuel, wood in particular, the whole plant may be utilised. Again, by-products or wastes derived from food crop production or processing may be used and hence have some value. As a result the characteristics of a production system may vary quite substantially, depending on the end use to which the crop is to be put. In the same way breeding objectives differ. In food crops, yield is a product of both quantity and quality (in terms of nutritional value, appearance, palatability, ease of harvest, storability and so on). Trees grown for paper pulp or timber as well as crops producing fibre such as cotton or sisal again have their own particular qualities which must be enhanced during breeding improvements.