Fig 1.
Field pictures of studied yam species.
(A) D. rotundata female plant being pollinated using a pin a binocular magnifying glass, (B) D. rotundata male plants at flowering stage, (C) D. rotundata green fruits, (D) D. alata female plant at flowering with some flowers bagged, (E) D. alata male plants at flowering stage, (F) D. alata green fruits. D. alata is characterized by angular stem, high biomass (vigor), and late maturity (~10 months) while D. rotundata has round/circular and thorny stem with hairy tubers and matures in ~8 months.
Fig 2.
Variations in weather conditions for 2020 and 2021 crossing windows, IITA Ibadan station.
Week 1 corresponds to 1st week of July while Week 27 corresponds to the last week of December. (A) D. rotundata crossing window started early August (Week 5) and ended mid-October (Week 14). (B) D. alata crossing window started in mid-October (Week 14) and ended early December (Week 21). (C) trends of daily variations in solar radiation and windspeed, (D) trends of daily variations in temperatures and relative humidity. On the time axis for (C) and (D), 0 refers to midnight while 23 refers to 11 p.m. of the same day. Highlighted hours (8 a.m. to 5 p.m.) correspond to crossing hours. Tmax = maximum temperature, Tmin = minimum temperature, RH = relative humidity.
Fig 3.
Pollination success across crossing hours: (A) D. alata, (B) D. rotundata.
Fig 4.
Dynamics of pollen germination rates across day hours.
Fig 5.
Pollination success rates across crossing months for 2020 and 2021.
(A) D. alata and (B) D. rotundata. The number 8 refers to August and 12 to December.
Fig 6.
Influence of the time interval between flower bagging and crossing on pollination success rates.
Fig 7.
Dynamics of SPE, SSR and SV across crossing months.
Monthly variability in SPE for D. alata (A) and D. rotundata (B), monthly variability in SSR for D. alata (C) and D. rotundata (D). Monthly variability in seed viability for D. alata (E) and D. rotundata (F). The number 8 refers to August and 12 to December.
Table 1.
Pollination time and seed production efficiency (SPE), seed setting rate (SSR) and seed viability (SV).
Fig 8.
Relationships among yam pollination traits and weather parameters.
CR = crossability rate/pollination success, SSR = seed set rate, SPE = seed production efficiency, SV = seed viability, Evp = evaporation, windpeed = wind speed, SolRad = solar radiation, Min T = minimum temperature, MaxT = maximum temperature, Min RH = minimum relative humidity, MaxRH = maximum relative humidity.