Applications of xerophytophysiology in plant production: Potato yield increase induced by drying the cut trace of seed tuber blocks

Seed tubers of potato are usually cut into blocks to reduce seed cost, break dormancy and induce dominance while desiccation of the tuber blocks is prevented. In the present research, the cut trace of the seed tuber blocks was intentionally dried as a treatment to induce positive xerophytophysiological regulations. Drying the seed tuber block cut trace induced more production of O 2 , which might act as a stimulation signal, and consequently activate the antioxidant enzyme, SOD. The stimulation of drying the cut trace was not strong enough to activate POD and CAT and showed also no damage to cells, which was confirmed by unchanged MDA concentration. Properly drying the cut trace induced osmotic adjustment, leaf turgor improvement, disease resistance and yield increase in the potato crop although severely drying dramatically decreased plant growth and tuber yield. These results were confirmed similar under all the three different organic material application regimes although the surface soil layer application was more favourite to the potato crop. Analysis of pressure-volume curve showed that active solute accumulation was higher, symplastic water fraction was larger and osmotic potential at plasmolysis was lower in plots of drying cut trace compared with the non-dry controls. Leaf turgor potential at both midday and at full turgid status was maintained higher in plots of drying cut trace. High maintenance of leaf turgor and symplastic water fraction was accountable for the improved tuber yield. Higher osmotic potential and relative water content at incipient plasmolysis suggested higher stress tolerance in the potato plants treated by drying cut trace of the seed tuber blocks. Higher water retention ability analyzed by using excised leaf transpiration declining curve suggested higher resistance to water stress and disease. In conclusion, properly drying cut trace of seed tuber blocks was feasible to improve potato crops as one of applications of xerophytophysiology in plant production.