FIELD PERFORMANCE OF PEAT-LITE MIX ENCAPSULATED SMALL MINITUBERS

Small minitubers (1.3 to 1.9 cm diameter), produced in the greenhouse from tissue culture plantlets are usually discarded because they are u ndersized for field planting. They have potential as a means of expand ing the production of basic nuclear potato seedstocks. Field trials we re conducted to evaluate the performance of greenhouse-produced minitu bers at 15 and 30 cm spacings, with one or two minitubers/hill, and wi th or without encapsulation in a moist ball of artificial greenhouse p eat-lite mix. All minitubers were green-sprouted for about two weeks u nder 16 hr/day fluorescent lighting before planting. Encapsulation in moist peat-lite mix significantly increased total yield by an average of 44% over minitubers without the soil mix. Independent of encapsulat ion, closer seed spacing and two minitubers/hill increased yields by a n average of 35% and 20%, respectively, compared to wider spacing and one minituber/hill. Yields of encapsulated minitubers compared favorab ly with cut (50 gm) and whole (80 gm) seed, averaging 103% of the cut and 87% of the whole seed yields, respectively. These results indicate that small minitubers can be used effectively to expand production of basic nuclear seedstocks.