The sound absorption property of polyurethane (PU) foams loaded with natural tea-leaf fibers and luffa cylindrica (LC) has been studied. The results show a significant improvement in the sound absorption property parallel to an increase in the amount of tea-leaf fibers (TLF). Using luffa-cylindrica as a filler material improves sound absorption properties of soft foam at all frequency ranges. Moreover, an increase in the thickness of the sample resulted in an improvement of the sound absorption property. It is pleasing to see that adding tea-leaf fibers and luffa-cylindrica to the polyurethane foam demonstrate a significant contribution to sound absorption properties of the material and it encourages using environmental friendly products as sound absorption material in further studies.
The role of the tea commodity in the economy of Indonesia is quite strategic. Various types of microorganisms in nature have been known to increase the benefit of the root function, suppress disease, and accelerate plant growth. This study aimed to determine the potential of indigenous bacteria (Azoto II-1, Acinetobacter sp., bacteria Endo-5, bacteria Endo-65 and Endo-76) on the growth of tea plants and their potential in increasing resistance to blister blight disease. The test of microbes’ potential effect on growth and blister blight was conducted in Gambung, West Java in an experimental field using a randomized block design (RBD) with six treatments and each treatment was replicated four times. The composition of the treatments was: A) Endo-5; B) Endo-65; C) Endo-76; D) Azoto II-1; E) Acinetobacter sp.; and F) control (without microbes). Bacterial suspension was applied directly to the soil at a dose of 2 l · ha−1. The bacterial suspension was applied six times at 1 week intervals. The results of field observations indicated that the intensity of blister blight decreased in all treatments but did not significantly differ from the control. Meanwhile, the results of Acinetobacter sp. treatment in tea shoots was 17.26% higher than the control.
The chemical composition of tea tree (Melaleuca alternifolia) and wintergreen (Gaultheria procumbens) essential oils as well as their phytotoxic effects against two invasive species – Cortaderia selloana and Nicotiana glauca – were studied. Fifty-eight compounds accounting for 98.89–99.94% of the total commercial tea tree and wintergreen essential oils were identified by Gas Chromatography-Mass Spectrometry (GC-MS) analysis. Tea tree essential oil with terpinen- 4-ol (28.37 ± 0.05%) followed by 1,8-cineole (15.81 ± 0.06%), γ-terpinene (15.60 ± 0.03%), α-pinene (10.92 ± 0.08%) and α-terpinene (8.52 ± 0.01%) as the main compounds did not produce significant effects against seed germination and hypocotyl growth of N. glauca, but showed significant effects in seed germination inhibition of C. selloana (34.69%) as well as in hypocotyl (60.96%) and radicle (62.55%) growth, at the highest dose (1 μl ⋅ ml–1) assayed. High amounts of methyl salicylate (99.63 ± 0.02%) were found in G. procumbens essential oil with remarkable phytotoxic effects in C. seollana. Methyl salicylate inhibited seed germination (77.38%) and hypocotyl and radicle growth (96.38% and 96.65%, respectively) at the highest dose (1 μl ⋅ ml–1) assayed. Wintergreen essential oil constitutes an eco-friendly alternative to control the high capacity of invasiveness of C. selloana.