Shade and nitrogen fertilization affect forage accumulation and nutritive value of C4 grasses differing in growth habit

Abstract

Light reduction in silvopastoral systems and self‐shading in treeless grasslands can lead to shade‐avoidance responses by tropical grasses. Light environment in association with nitrogen (N) supply influence the growth and nutritive value of forage grasses. This study aimed to quantify forage accumulation (FA) and forage nutritive value of tropical grasses differing in growth habit in environments with contrasting light and N resources. A field study was conducted using ‘Jiggs’ bermudagrass [Cynodon dactylon (L.) Pers.] and ‘Mulato II’ hybrid brachiariagrass (Urochloa spp). Full‐sun environments were compared with shaded environments where shade cloth limited incident radiation to 45% of ambient. Low and high N treatments were imposed (30 and 120 kg N ha−1 after each harvest), resulting in a 2 × 2 × 2 factorial arrangement of treatments in four replicates of a randomized complete block design. Forage was harvested every 28 d from May to September in 2014 and 2015 to determine FA. Herbage crude protein (CP) concentration and in vitro digestible organic matter (IVDOM) were assessed. Annual FA was greater for Mulato II than Jiggs and for high‐N and full‐sun treatments. Species showed similar CP concentrations, but Mulato II had greater IVDOM than Jiggs, likely due to a greater leaf percentage. Shade increased CP concentration of the forages whereas effects on IVDOM were not consistent. Although more productive with greater leaf percentage and nutritive value than decumbent, stoloniferous Jiggs, upright‐growing, bunchgrass Mulato II was not persistent when multiple freeze events occurred during winter, limiting its adoption in cooler subtropical environments.

Suitability Evaluation of Three Tropical Pasture Species (Mulato II, Gatton Panic, and Rhodes Grass) for Cultivation under a Subtropical Climate of Australia

“…These results together with pasture stem height and leaf height may potentially explain the vertical distribution of nutritive values in the overall sward. Generally, results of the present study supported the hypothesis that BM outperformed the other two species in quality parameters in relation to the leaf, stem, and whole plant, which was in agreement with a number of other studies [2,46,47,51,60]. The reason for BM producing relatively higher quality herbage is predominantly associated with its plant morphological composition (high leaf: stem) [10].…”

“…Pasture canopy structure is partly determined by genetics and is expected to vary within genotypes. Brachiaria Mulato II is an improved Brachiaria hybrid developed to produce quality herbage for livestock [10,49], and observed canopy structure parameters of the present study confirmed its superior agronomic performances reported in other tropical and subtropical areas around the world [13,[46][47][48][50][51][52]. In addition, the higher forage yield of GP explains the forage-yielding potential of the genus megathyrsus explained elsewhere [2].…”

Forage accumulation, nutritive value, and grazing efficiency on rotationally stocked ‘Zuri’ guineagrass pastures as affected by pre‐graze canopy height and N rate

“…The FA and forage nutritive value are generally affected by pre‐graze canopy height, and when associated with an adequate N supply (Moreno et al, 2022; Pontes et al, 2017) may allow for a greater stocking rate (Gurgel et al, 2020). Greater N inputs (e.g.…”

The Responses of Stem and Leaf Functional Traits of Medicago sativa and Bromus inermis to Different Mixed Planting Patterns

“…The gray correlation analysis and the dry matter yield of forage stem and leaf traits showed leaf area, stem diameter, and leaf length were the top three stem and leaf traits that contributed more to the dry matter yield of alfalfa [40]. The slower-growing species in the mixed sowing system were affected by the shade effect because shade strongly affects the development of forages by changing their biomass allocation strategy and reducing the growth height of the forage [41][42][43]. The stem length of awnless brome contributed more to its dry matter yield than stem diameter, suggesting that adequate light resources increase the dry matter yield of awnless brome.…”