The demand for lemongrass (Cymbopogon citratus) is for its high citral content. Early or delayed harvesting of lemongrass affected essential oil and citral content. The objective of the study was to determine the effects of three maturity stages at harvest of lemongrass on essential oil, chemical composition and citral contents. The lemongrass plant was planted using a randomized complete block design with four replications, at the University Agriculture Park, Universiti Putra Malaysia. The plants were harvested at 5.5, 6.5, and 7.5 months after planting. After harvest, the essential oil, chemical composition and citral contents were analysed using gas chromatography-mass spectrometry (GC-MS) analysis. There were significant effects of maturity stages on essential oil and citral contents. Lemongrass harvested at 5.5 and 6.5 months after planting had significantly higher oil contents than those harvested at 7.5 months. A total of 65 compounds were detected from all the three stages of maturity. However, only 13 compounds were present at each of the maturity stage. Among 13 compounds, only 7 compounds (β-myrcene, 3-undecyne, neral, geranial, nerol, geranyl acetate and juniper camphor) had a concentration of greater than 1%. The citral content at 6.5 months after planting was higher by 11.4% than at 5.5 months after planting. The citral content decreased by 5.4% when lemongrass was harvested at 6.5 compared to at 7.5 months after planting. Citral content peaked at 6.7 ± 0.3 months after planting. Thus, maturity stage at harvest influenced essential oil and citral contents of lemongrass. Therefore, lemongrass should be harvested at the appropriate level of maturity in order to achieve high quality essential oil and lower production cost.

Clinacanthus nutans is a well recognized medicinal herb for its high phytochemical contents. Several aspects may contribute to the phytochemical contents, and thus determine the quality and efficacy of an herb. An experiment was conducted using a completely randomized design (CRD) with five replications, in a factorial arrangement of treatments. including two plant parts harvested at two different stages such as young leaves, young stems, matured leaves and matured stems, and four different storage durations such as 1, 2, 3 and 4 days. The study was aimed at determining how storage duration affects selected phytochemical contents of different plant parts of C. nutans at different harvesting stages. Total phytochemical content, total flavonoids content and DPPH radical scavenging activities are higher in young plants than in old plants, moreover, all those compounds are higher in leaves than in stems, and decrease gradually due to storage. Phytochemical, ascorbic acid and chlorophyll content of C. nutans differ among different plant parts and change due to storage. In general, young plant parts contain higher amount of phytochemicals, ascorbic acid and chlorophyll compared with matured parts confirming that phytochemicals content of C. nutans decreases when plants tend to maturity. Prolonged storage reduces phytochemical, ascorbic acid and chlorophyll content of C. nutans,which demands fresh use of this medicinal herb to avoid phytochemical losses. Further research focusing on the proper storage is necessary to minimize phytochemicals losses of C. nutans.

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Andrographis paniculata (Burm. F.) Nees. is considered as the herb of the future due to its precious chemical compounds, andrographolide (ANDRO), neoandrographolide (NAG) and 14-deoxyandrographolide (DAG). This study aims to profile the metabolites in young and mature leaf at six different harvest ages using 1HNMR-based metabolomics combined with multivariate data analysis. Principal component analysis (PCA) indicated noticeable and clear discrimination between young and mature leaves. A comparison of the leaves stage indicated that young leaves were separated from mature leaves due to its larger quantity of ANDRO, NAG, DAG, glucose and sucrose. These similar metabolites are also responsible for the PCA separation into five clusters representing the harvest age at 14, 16, 18, 20, 22 weeks of leaves extract. Loading plots revealed that most of the ANDRO and NAG signals were present when the plant reached at the pre-flowering stage or 18 weeks after sowing (WAS). As a conclusion, A. paniculata young leaves at pre-flowering harvest age were found to be richer in ANDRO, NAG and DAG compared to mature leaves while glucose and choline increased with harvest age. Therefore, young leaves of A. paniculata should be harvested at 18 WAS in order to produce superior quality plant extracts for further applications by the herbal, nutraceutical and pharmaceutical industries.

Colletotrichum gloeosporioides causes anthracnose disease in papaya fruit resulting in tremendous economic loss due to its latent infection. This study aimed to evaluate the biocontrol activity of antagonistic yeasts against C. gloeosporioides in papaya and determine the possible mechanism involved. One hundred and ten yeast strains were isolated from different parts of the papaya plant. Among them, only five strains, namely F001, F006, L003, FL013 and LP010, showed more than 55% radial growth inhibition of C. gloeosporioides. These five potent yeast strains were further evaluated in vitro and in vivo. The results indicated that strain F001 had the strongest biocontrol activity based on spore germination and fungal growth inhibition. In vivo, the strain F001 caused 66.7% and 25% reductions in disease incidence and severity, respectively. Based on molecular identification, the strain F001 was confirmed as Trichosporon asahii. Despite there was no significant induction of defense enzyme activities found on the treated fruits, SEM observation showed direct attachment of T. asahii with the fungal hyphae and interfere in their establishment to the fruit surface. Based on these findings, the antagonistic yeast T. asahii strain F001 may be used as a potential natural biological control agent against anthracnose disease in papaya fruit.