Light Interception and the Growth of Pastures under Ideal and Stressful Growing Conditions on the Allegheny Plateau

Abstract

Pasture-based livestock production is impacted by management and weather. In pastures, there is conflict between leaf retention for plant growth and leaf harvest for animal nutrition. Defoliated pastures with low light interception (LI) may have a low forage growth rate (FGR), while excessive growth shades leaves, reducing FGR and resulting in an S-shaped regrowth curve. To optimize production, it is best to keep FGR linear. Three studies were conducted to evaluate the impact of management and weather on FGR. Replicated pastures were used to measure FGR when grazed from 25 to 10 cm and allowed to regrow. The impact of alternative defoliation timings and intensities on FGR were studied using clipped treatments at three recovery intervals and two stubble heights. Variability in FGR was studied using a field validated plant growth model. Of the 24 growth periods studied, two displayed exponential, 12 linear and 10 linear-plateau growth. There was no effect of FM on growth curve form. In May and June, LI increased with canopy height, up to 0.93. Stubble height and days of growth impacted FGR with an interaction. There was no treatment impact on root density. Weather caused variation in FGR. A low FGR risk occurs at high elevations; greater risk occurs east of the plateau.

Herbage Yield, Lamb Growth and Foraging Behavior in Agrivoltaic Production System

“…Light interception is one of the primary drivers of plant growth together with nutrients, temperature and available soil moisture (Rayburn and Griggs, 2020). Previous studies that were conducted in artificial shade conditions (Varella et al, 2001;Dodd et al, 2005) or in silvopastoral systems (Devkota et al, 2009) reported that light was the main determining factor for the understory forage production.…”

Can Soil pH Correction Reduce the Animal Supplementation Needs in the Critical Autumn Period in Mediterranean Montado Ecosystem?

“…Regarding the effect of tree canopy on pasture productivity, the competition for resources water, light, and nutrients are considered as the main reason for decreased yields UTC in winter and especially in spring [15,16]. However, given that tree canopy contributes to less pasture evapotranspiration and, as a consequence, guarantees higher soil moisture content [19], and also because UTC areas are usually more fertile [19], the critical factor for the lower pasture productivity under tree canopy must result from the combination of four sub-factors: (i) lower incidence of solar radiation, which affects directly the physiological processes of plants and net DM production [15], since light interception by plant leaves is used in photosynthesis to provide energy for plant maintenance, to grow new leaves and roots, and to produce carbohydrates [36]; (ii) lower land cover, due to the release of inhibitory substances resulting from leaves and other tree residues [32]; (iii) development of less productive botanical species; Graß et al [16] highlight the shadow inhibitor effects specifically on the growth of legumes; and (iv) livestock grazing, which, according to Hussain et al [37] can have an important influence on sward composition, quality and production UTC and OTC.…”

Floristic Composition: Dynamic Biodiversity Indicator of Tree Canopy Effect on Dryland and Improved Mediterranean Pastures

“…Tree canopy effect is potentially positive for the development of the pasture in winter, preventing the soil/pasture surface temperature from falling to values close to 0 • C. On the other hand, the lower soil/pasture surface temperature UTC during spring months may have a positive effect on the pasture by delaying the conclusion of the vegetative cycle (and the consequent quality degradation) [42], but it may also lead to lower pasture productivity in these areas, reflecting lower light transmission to the understory and, consequently, the reduction of photosynthetic rates in zones with lower sun exposure [43]. Light interception by plant leaves is used in photosynthesis to provide energy for plant maintenance, to grow new leaves and roots, and to produce carbohydrates stored within cells and translocated to energy sinks [44].…”