Photosynthesis and translocation in relation to plant development

Meaningful discussion of such physiological activities as they bear on yield can be no better than the perspective within which they are viewed so far as plant developmental pattern limitations. Therefore, some time is devoted to discussing developmental characteristics in sorghum in general to be followed by a consideration of photosynthesis, translocation, etc. in the context of yield analyses when possible. Our understanding of the sorghum crop still remains quite limited. The store of information regarding the crop is steadily increasing. However, knowledge of physiologic responses is inadequate yet to state the order of yield limiting physiologic functions with the degree of certainty which seems desirable for cultural and genetic improvement purposes. Our perspective is improving regarding limitations in the various developmental stages. Rapid, simple developmental stage evaluations are permitting a more precise field evaluation of both the time production factors and metabolic efficiency production factors in sorghum. Hopefully this is true to the extent that it will be useful in plant breeder selection work. Progress in photosynthesis and assimilate transport work is continuing as it relates to intraplant competition. Much work needs to be done on respiration. A potentially productive procedure for evaluating photosynthesis in the canopy as a whole has been devised and likely will be a useful tool for plant-type-field stand geometry investigations in the near future. The need exists for developing additional field screening techniques. Also much work needs to be done at the molecular level to advance our understanding of control mechanisms regarding differentiation of floral parts and control of the major physiologic processes.