Harvest management based on leaf stage of a tetraploid vs. a diploid cultivar of annual ryegrass

Abstract

Leaf stage-dependent defoliation is linked to the plant's physiological status and may be a more suitable criterion than time-based intervals for harvesting forage grasses, but no reports of research with annual ryegrass (Lolium multiflorum Lam.var. westerwoldicum) were found. To address this, a 2-year field study was carried out at Raymond, MS, on a Loring silt loam soil (fine-silty, mixed, thermic Typic Fragiudalfs). Forage production, morphological characteristics and nutritive value responses to defoliation based on leaf stage (2, 3 and 4 leaves per tiller) and two residual stubble heights (RSH; 5 and 10 cm) of a tetraploid ("Maximus") vs. a diploid ("Marshall") cultivar of annual ryegrass were quantified. Forage harvested, in 2011, increased linearly as leaf stage increased from 7.3 to 8.8 Mg/ha, but during 2012 was least (7.0 Mg/ha) at 3-leaf stage and similar at the other two leaf stages (7.6 Mg/ha). Tiller density was less for Maximus (1,191

Functional Traits, Morphology, and Herbage Production of Vernalised and Non-Vernalised Chicory cv. Choice (Cichorium intybus L.) in Response to Defoliation Frequency and Height

“…Before vernalisation between February and May 2018, all chicory treatments accumulated on average 6.4 ± 0.98 kg/ha DM herbage per GDD. Variation in accumulated herbage mass in response to contrasting regrowth intervals of the same forage species likely result from differences in plant density and plant size [28,51]. In the current experiment, no significant differences in plant density between treatments were found (Table 5).…”

“…Our results showed that both the size of the roots and their concentration of WSC were lower for the 300 GDD plants than the 600 GDD plants before and after vernalisation. Similarly, Donaghy and Fulkerson [57] and Solomon et al [51] have reported a decline in root WSC concentration from longer to shorter defoliation intervals in perennial and annual ryegrass plants, respectively.…”

“…When comparing the two regrowth intervals, individual plant biomass was greater for 600 GDD plants than 300 GDD plants. Generally, plants (grasses, legumes or herbs) that have reached reproductive stage are more productive in terms of individual plant biomass [15,21,51]. The increased plant weight for 600 GDD plants was related to stem weight.…”

“…Following defoliation, the leaf photosynthetic rate increases and the actively growing points in plants become high priority sinks of the currently produced photosynthetic carbon and the reserves located in the roots [46,55]. Consequently, the root size and concentrations of WSC tend to be lower in more frequently grazed plants of Lolium perenne L. than in less frequently grazed ones [51,56]. Our results showed that both the size of the roots and their concentration of WSC were lower for the 300 GDD plants than the 600 GDD plants before and after vernalisation.…”

Ontogenetic development of <em>Pennisetum purpureum</em> cv. Napier: consequences for grazing management

“…However, due to difficulty of measuring aspects of light interception and LAI in field conditions, the challenge for scientists in grassland ecophysiology is to translate the ecophysiological principles into sward characteristics that should be as efficient as LAI and ease to apply, so farmers could monitor the grazing process and make the "complex seem simple" (Chapman, 2016). In this context, several grazing management guidelines have been developed, with the definition of sward height targets (Carvalho et al, 2016;Hodgson, 1990) and leaf stage indicator (Fulkerson and Slack, 1995;Gomide and Gomide, 1999;Solomon et al, 2017) being some of the most used. Independently of the sward structural characteristics used, the idea is to maintain the optimum balance between leaf growth and senescence favoring high herbage accumulation and utilization efficiency, ensuring pasture persistence and herbage consumption by animals.…”