Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/5/2017
Publication Date: 8/3/2017
Publication URL: https://handle.nal.usda.gov/10113/5832849
Citation: Hale, A.L., White Jr, P.M., Webber III, C.L., Todd, J.R. 2017. Effect of growing media and fertilization on sugarcane flowering under artificial photoperiod. PLoS One. 12(8):1-10. https://doi.org/10.1371/journal.pone.0181639.
Interpretive Summary: The sugarcane variety development program at the USDA-ARS Sugarcane Research Unit in Houma, LA aims to maximize the number of flowers available for making crosses for the production of sugarcane seed. In the temperate environment of Houma, flowering is dependent on the artificial manipulation of the daylight hours to simulate the day length of the tropics in which the parental plants would naturally flower. Even manipulating the day length, not all sugarcane stalks produce a flower, making the process time consuming and costly; thus breeders seek ways to increase the number of flowering stalks. In a three-year study, the effect of growing media (soil) and the timing of fertilizer applications on sugarcane flowering and the number of days to flowering (DTF) were studied. The leading Louisiana commercial sugarcane variety, ‘HoCP 96-540’, which does not flower naturally, was grown in pots and underwent the standard photoperiod treatment used in the breeding program. The variety was planted on four different growing media and subjected to three different fertilizer applications. The Control fertilizer treatment consisted of a one-time incorporation of a slow-release fertilizer (Osmocote) at planting. In addition to the incorporation of Osmocote at planting, for the continuous treatment, the variety received supplemental fertilizer three times per week beginning in June with the initiation of day length manipulation and continuing through October. Plants in the partial treatment received the slow-release fertilizer at planting as well as supplemental fertilizer between September and October, the peak time for flowering. In Louisiana, ceasing application of fertilizer prior to the beginning of photoperiod treatments is generally accepted to improve flowering. Results from this study indicate that this practice should be reconsidered. Flowering did not appear to be influenced by the different soil media. When averaged across growing media, the control treatment (standard practice) produced 21.2% less flowers than the continuous treatment, where fertilizer was supplied throughout the season. In addition, the continuous fertilizer treatment produced flowers, on average across growing media, four days earlier than the control treatment and six days earlier than the partial treatment. Evidence from this three-year experiment indicates that we should consider modifying plant nutrition management to ensure soil fertility is adequate for flowering.
Technical Abstract: The USDA-ARS Sugarcane Variety Development Program in Houma, LA aims to maximize the number of panicles available for crossing through artificial manipulation of the environment. In a three-year study, the effect of growing media, fertilizer treatment, and their interaction on sugarcane flowering (% of panicles emerged), and number of days to flowering (DTF) under an artificial photoperiod treatment were assessed. The commercially-available sugarcane cultivar, ‘HoCP 96-540’ was planted in 2.8-L pots and subjected to the standard local photoperiod treatment. The cultivar was planted in four growing media (RediEarth Seedling and Germination Mix, Fafard, MetroMix902, and MetroMix900) and subjected to three different fertilizer applications. In the control treatment, fertilizer application was stopped prior to the commencement of the photoperiod treatment as practiced in some sugarcane breeding programs. The continuous treatment consisted of an application of a 10 ml solution of a NPK three times a week between June and October. The partial treatment consisted of applications of the same NPK solution applied post-initiation between September and October. Nitrogen starvation prior to the commencement of the photoperiod treatment is generally accepted to improve flower initiation; thus the standard practice is to cease nitrogen application two weeks prior to beginning a photoperiod regime. The growing media used in this study did not have a significant effect on days to flowering or percent panicle emergence. In our study, the control fertilizer treatment showed a flower induction percentage across all growing media types of 21.2% less than a continuous fertilization regime. Furthermore, a significant trend was observed between fertilization treatments and days to flowering, with the continuous treatment producing panicles, on average across growing media, four days earlier than the control treatment, and six days earlier than the partial treatment. Evidence across this three-year experiment indicates that we should consider modifying plant nutrition management as soil fertility was found to be inadequate.