Changes of photosynthetic pigments and phytol content at different levels of nitrogen fertilizer in Italian ryegrass fresh herbage and hay

Abstract

The content of photosynthetic pigments in herbage not only has a strong antioxidant function, but also can improve the health of animals and the quality of livestock products after being ingested by ruminants. Increasing the content of photosynthetic pigments can improve the feed value of herbage, which is of great significance in the process of animal feeding. The experiment aimed to investigate the effect of nitrogen (N) fertilizer levels on the contents of photosynthetic pigments and phytol in fresh Italian ryegrass (IR) herbages and their changes after drying under natural condition over two consecutive seasons. IR variety: Ace (for 2013-2014 season) and Inazuma (for 2015-2016 season) were planted in 3 blocks (4 × 6 m) from two separate fields (≥1 ha), three plots (2 × 2 m) were arranged in each block and three fertilization treatments, control: 0 kg N/ha, 60 N: 60 kg N/ha, and 120 N: 120 kg N/ha, were applied for each block. The results revealed that the crude protein, ether extract, photosynthetic pigments and phytol in IR (fresh herbage and hay) were increased with increasing N fertilizer levels. Photosynthetic pigments decreased obviously by hay preparation (chlorophylls: 40%-70%, phytol: 25%-47%, β-carotene: 72%-90%, lutein: 31%-69%). The decomposition of phytol and β-carotene was not affected by the growing year and N fertilizer levels. However, the decomposition of chlorophyll and lutein was affected by growing year, which was higher in 2014 than that in 2016. Also, the contents of total phytol and lutein of the fresh herbage and hay harvested in 2016 were higher (p < .05) than those harvested in 2014. In conclusion, higher N fertilizer levels could increase the photosynthetic pigments and phytol content in IR fresh herbage which contributes to improving the feed value. However, the content of photosynthetic pigments and phytol in IR hay decreased significantly. IR variety may also affect the nutrient content and their degree of decomposition during drying.

Dynamics and correlations of chlorophyll and phytol content with silage bacterial of different growth heights Pennisetum sinese

“…That result in pigment yield was higher in H3 or H4. In addition, the pigment content of P. sinese was reported for the first time in this study, the content were significantly higher than Italian ryegrass (Lv et al, 2017;Lv et al, 2020;Lv et al, 2021). Besides the cultivation conditions, the plants characteristics (variety or harvesting stage) also determine the differences in photosynthetic pigment content (Lv et al, 2017;Lv et al, 2021).…”

“…In addition, the pigment content of P. sinese was reported for the first time in this study, the content were significantly higher than Italian ryegrass (Lv et al, 2017;Lv et al, 2020;Lv et al, 2021). Besides the cultivation conditions, the plants characteristics (variety or harvesting stage) also determine the differences in photosynthetic pigment content (Lv et al, 2017;Lv et al, 2021). As a kind of typical plant, the photosynthesis would be more effective under full sunlight, thus P. sinese produce the photosynthetic pigments more beneficial.…”

“…According to previous reports, the contents of phytol or chlorophyll in forage were affected by many factors, for instance, forage variety and growth period ( Lv et al., 2021 ). In addition, cultivation measures affect these pigment content of forage, Hák et al.…”

“…According to previous reports, the contents of phytol or chlorophyll in forage were affected by many factors, for instance, forage variety and growth period (Lv et al, 2021). In addition, cultivation measures affect these pigment content of forage, Haḱ et al (1993) and Lv et al (2017) reported that the chlorophyll and phytol contents increased when applied nitrogen fertilizer and harvested earlier.…”

“…In addition, cultivation measures affect these pigment content of forage, Haḱ et al (1993) and Lv et al (2017) reported that the chlorophyll and phytol contents increased when applied nitrogen fertilizer and harvested earlier. Moreover, the forage processing and modulation method also affects the pigment content; Lv et al (2021) reported that drying can obviously reduce the content of chlorophyll and phytol in the harvest grass. On the contrary, ensiling could preserve the phytol in temperate grasses Italian ryegrass well (Lv et al, 2017;Lv et al, 2020).…”