Phenological development of subterranean clover cultivars under contrasting environments

Abstract

Six subterranean clover cultivars (representing early and late flowering genotypes from three subspecies) were used to describe and quantify their phenological development. The vegetative (V) and reproductive (R) development phases, in response to different environments created by eight sowing dates were quantified. The period from sowing to emergence was constant in thermal time at 110°Cd and the first trifoliate appeared at ~300°Cd. Crops sown in autumn had the longest period from runner initiation until floral bud initiation (R1), which would allow an extended period of grazing, particularly for later flowering cultivars like ‘Denmark’. To maximise seed set (particularly in year 1) a maximum period between R3 and R11 is required (seed set window). This ranged from 319 ± 42.3°Cd for ‘Leura’ to 661 ± 73.1°Cd for ‘Narrikup’. The complete crop life cycle from sowing (V0) to maturity (R11) ranged from 1269 ± 31°Cd (equivalent of 123 ± 6.3 days) for ‘Antas’ sown in July to 2799 ± 47°Cd (300 ± 3.9 days) for ‘Woogenellup’. When sowing occurred in an increasing photoperiod (June–November) the life cycle of all cultivars was 59% shorter than when sown in a decreasing photoperiod. The numeric scale was able to describe all the variation in the phenological phases and could be used to quantify thermal time requirements for specific phenophases. This would allow subterranean clover management to be optimised (husbandry, grazing and seed harvest) at a local level, and provides the basic parameters for inclusion in annual pasture simulation models.

Flowering responses of serradella (Ornithopus spp.) and subterranean clover (Trifolium subterraneum L.) to vernalisation and photoperiod and their role in maturity type determination and flowering date stability

“…The experiment was conducted using a complete factorial combination of six cultivars × six vernalisation treatments × four photoperiod treatments × six replicates (Supplementary Table S1). At 16 days after sowing when the unifoliate leaf was visible in subterranean clovers (V2 stage, Teixeira et al . 2021) or the first pinnate leaf of the serradellas was visible, established cohorts of the six cultivars were subjected to one of six vernalisation (VRN) treatments (0, 1, 3, 5, 7 or 9 weeks, with 8 h photoperiod).…”

“…There are various terms used to describe branching patterns in different pasture legumes. Much of the subterranean clover literature describes the formation of nodes firstly on a main stem followed by branching in which new axes, referred to as ‘runners’, are formed and from which subsequent axes, ‘laterals’, can form (Aitken and Drake 1941; Teixeira et al . 2021).…”

“…These requirements and intrinsic earliness of various subterranean clover cultivars are well studied (Aitken 1955, 1974; Evans 1959; Collins and Smith 1975; Salisbury et al . 1987; Teixeira et al . 2021) but there is only limited information concerning aspects of the response to photoperiod and vernalisation available for cultivars of yellow or French serradella (Gladstones and Devitt 1971; De Ruiter and Taylor 1979; Fu et al .…”