PLANTING MATERIALS FOR WARM TROPIC POTATO PRODUCTION - MOTHER-PLANT MANAGEMENT FOR THE PRODUCTION OF ROOTED CUTTINGS

Four factors (shade, photoperiod extension, age of mother plant, and m other-plant origin) relating to mother-plant management were studied a t a tropical site. Mother plants were mostly grown from whole tubers f rom cool conditions. Seedlings from true potato seed were also used as mother plants in one experiment. A 25% reduction of irradiance induce d most branching per mother plant, and longer internodes compared to t he control resulting in more effective rooting of stem cuttings. Dense r shade reduced branching and rooting. Photoperiod extension with inca ndescent bulbs was effective in delaying tuber initiation of rooted cu ttings, more so at cooler nights (<16 degrees C). Mother-plant age, at the time cuttings were taken, showed no consistent effect on yield po tential; those from 30 to 60 days at the time of cutting were all equa lly induced to tuberize. There were no significant differences between yields from rooted cuttings from mother plants derived from tubers pr oduced either under cool or warm conditions. This is encouraging for p otato production in the lowland tropics since it obviates dependence o n cool-produced tubers as planting materials.