Inducing potato tuber formation at low elevation of tropical region by foliar spray of PGR mixtures at different application times

Abstract

Growing potato crops at low elevation in the tropical region may face many problems related to high temperature, such as an increase in endogen GA3 levels, causing the inhibition of tuber formation. Suppressing GA3 biosynthesis, by applying a mixture of plant growth regulators (PGRs), is of important. The objectives of this experiment were to study the best PGR mixtures, PGR application time, and their interaction in promoting tuber formation at low altitude of tropical areas in Indonesia. The experiment used a completely randomized design arranged in factorial (2 factors, 3 replications). The first factor was a mix of plant growth regulator solution (M), consisting of 4 levels, which were: M0 = No PGR; M1 = 10 ppm 2,4-D + 100 ppm Daminozide, M2 = M1 +10 ppm BAP, M3 = M1 + 25 ppm COU, and M4 = M1+ 500 ppm PBZ. The second factor was application time of the solutions (T), consisting of 3 levels, which were: T1 = 3, 4, 5, 6 weeks after emergence (WAE), T2 = 3, 4, 5 WAE, and T3 = 3, 4 WAE. The results showed that all of the PGR mixtures promoted tuber formation with 10 ppm 2,4-D + 100 ppm Daminozide + 500 ppm Paclobutrazol was found as the best PGR mixture. Moreover, the best time to spray the mixture was 3,4,5,6 WAE. Finally, the best interaction between PGR and application time was10 ppm 2,4-D + 100 ppm Daminozide + 10 ppm BAP applied at 3,4,5 WAE.