Breeding of cassava is hampered by its poor flower production, flower abortion, and lack of reproductive prolificacy. The current work determined that ethylene signalling affects floral development in cassava and that the anti-ethylene plant growth regulator silver thiosulfate (STS) mitigates the effects of ethylene on flower development. STS did not affect the timing of flower initiation, but improved early inflorescence and flower development as well as flower longevity such that flower numbers were increased. STS did not affect shoot and storage root growth. Studies of silver accumulation and treatment localization support the hypothesis that the beneficial effects of STS are confined to tissues of the shoot apex. The most effective timing of application was before inflorescence appearance extending to post-flower appearance. Based on this work a recommended protocol for STS use was developed. This work has the potential to improve methods for enhancing cassava flower development in breeding nurseries and thereby synchronize flowering of desired parents and enable the production of abundant progeny of desired crosses.
Figure 1: The efect of spray application of STS on foral development; fower counts are for the frst tier of fowering and are means of four replicates of four genotypes (TMSI980002, TMEB 419, TME 204, and NASE 3). a STS Experiment 1 with 0.5 mM STS foliar spray; b STS dosage experiment with the indicated concentration in STS spray; c control TMSI980002 plant with the tier 1 branch region encircled where inforescence development had initiated, then aborted; d TMSI980002 plant treated with 0.5 mM STS with tier 1 branch region and inforescence/fowers encircled.