Pg. 33-37 The use of plant growth substances to reduce fruit drop and increase fruit size in litchi

It is known that the application of plant growth substances can effect fruit retention and fruit size, depending on the application time and the concentration used. Trials were undertaken in the Malelane and Nelspruit areas to determine the effect of the synthetic cytokinin, CPPU. and CPPU in combination with the gibberellins, ProGibb® (GA₃) and Promalin® (GA_{4_7}), on fruit size and retention of ‘HLH Mauritius·. Applications were made during early fruit development. With early treatments, two to seven days after full female bloom, fruit drop was significantly increased with CPPU and CPPU in combination with ProGibb® and Promalin®. No significant increase in fruit size was obtained. This caused a significant reduction in yield. With the later treatments, two to three weeks after full female bloom, no significant effect on fruit drop was observed. Although not significant, fruit size was slightly increased by the CPPU treatment alone. No significant increase in fruit size occurred, where CPPU was used in combination with ProGibb® and Promalin®.