Comparison of phenolic constituent in Hibiscus sabdariffa cv. UKMR-2 calyx at different harvesting times

The metabolic changes in the phenolics content of Hibiscus sabdariffa cv. UKMR-2 were investigated at different harvesting times based on the High-Performance Liquid Chromatographic method using a photodiode array detector (HPLC-PDA) with gradient elution. The antioxidant activity was also determined using 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity (DPPH) assay. The cultivation was executed under a control condition, and the calyces were separately harvested at four maturation stages. UKMR-2 calyces were extracted with water via sonication (50°C, 30 min). HPLC-PDA analysis showed two predominant anthocyanins, namely delphinidin-3-O-sambubioside (2.07-2.47 mg/g DW) and cyanidin-3-O-sambubioside (0.55-1.01 mg/g DW). In addition, ascorbic acid (3.34-9.88 mg/g DW), caffeic acid (0.08-0.09 mg/g DW) and chlorogenic acid (0.50-0.65 mg/g DW) were also detected in all maturity stages. Cyanidin-3-O-sambubioside content increased as the calyx became more mature, whereas the delphinidin-3-O-sambubioside, ascorbic acid, and chlorogenic acid content declined towards calyx maturity. The antioxidant activity gradually increased as the calyx ripening progressed. However, the activities did not differ significantly between the stages (p>0.05). The high content of total phenolic, total anthocyanins, and free radical scavenging activity were detected at Stage 4 (28-30 DAA) in UKMR-2, suggesting that this stage is the most appropriate maturity stage for harvesting H. sabdariffa cv. UKMR-2 calyces compared to the other maturity stages

Growth and phenolic constituents’ production in roselle (Hibiscus sabdariffa var. ukmr-2) as influenced by irrigation treatment

This study was carried out to investigate the influence of irrigation on the growth and phenolic content production of Hibiscus sabdariffa var. UKMR-2. The greenhouse cultivation for UKMR-2 was done under control condition using two different irrigation treatments; Water Treatment 1 (WT1) with 1.72 L/plant/day and Water Treatment 1 (WT2) with 0.86 L/plant/day. Roselle calyces were harvested at selected maturation stage and extracted with water via sonication (50 °C, 30 mins). Analysis of total phenolic, anthocyanin content and antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity (DPPH) assay was performed using water extract of roselle calyces. The growth parameters such as plant height, stem diameter, number of branches and leaves were also recorded. The result showed the mean value for WT1 and WT2 treatment respectively: total phenolic content (TPC) were 2.54±0.34 and 2.47±0.34 mg gallic acid equivalent (GAE)/g DW; total anthocyanin content (TAC) were 8.06±1.10 and 7.64±1.38 mg cyanidin-3-glucoside /g DW; IC50 value were 0.28±0.50 and 0.30±0.61mg/mL. WT1 treated plants growth and percentage yield tended to be more higher compared with WT2 treatments. However, there are no significant differences (p>0.05) recorded on the growth parameter with different irrigation treatment. The results also showed that different irrigation treatment have no significant influence on the TAC, TPC and antioxidant activity (p>0.05). All data showed higher quality on growth and calyx’s productivity (including higher concentrations of phenolic contents and antioxidant activity) in UKMR-2 from WT1. Therefore, WT1 (1.72 L/plant/day) is recommended option for roselle cultivation to produce higher phenolic contents, without negative effect on the growth and quality of roselle calyces

Physiological and growth response of rice plants (Oryza sativa L.) to Trichoderma spp. inoculants

Trichoderma spp., a known beneficial fungus is reported to have several mechanisms to enhance plant growth. In this study, the effectiveness of seven isolates of Trichoderma spp. to promote growth and increase physiological performance in rice was evaluated experimentally using completely randomized design under greenhouse condition. This study indicated that all the Trichoderma spp. isolates tested were able to increase several rice physiological processes which include net photosynthetic rate, stomatal conductance, transpiration, internal CO(2) concentration and water use efficiency. These Trichoderma spp. isolates were also able to enhance rice growth components including plant height, leaf number, tiller number, root length and root fresh weight. Among the Trichoderma spp. isolates, Trichoderma sp. SL2 inoculated rice plants exhibited greater net photosynthetic rate (8.66 μmolCO(2) m(−2) s(−1)), internal CO(2) concentration (336.97 ppm), water use efficiency (1.15 μmoCO(2)/mmoH(2)O), plant height (70.47 cm), tiller number (12), root length (22.5 cm) and root fresh weight (15.21 g) compared to the plants treated with other Trichoderma isolates tested. We conclude that beneficial fungi can be used as a potential growth promoting agent in rice cultivation

Kesan gelembung udara dan auksin bagi penginduksian akar pada tunas arundina graminifolia dalam sistem rendaman berterusan tertutup

Arundina graminifolia atau orkid buluh adalah orkid yang hidup di atas tanah, tahan panas dan penyakit, mudah dijaga, berbunga sepanjang tahun dan sangat sesuai untuk dijadikan tanaman landskap di kawasan terbuka. Kebiasaannya, A. graminifolia dibiak melalui pembahagian rumpun dan kultur tisu. Kadar pembiakan daripada kaedah ini adalah sangat rendah dan mengambil masa yang lama untuk memperbanyakkan bahan tanaman. Penggunaan sistem rendaman berterusan tertutup (CPIS) telah berjaya mempercepatkan penginduksian mata tunas A. graminifolia. Namun, penginduksian akar mengambil masa yang agak lama iaitu melebihi tiga bulan. Oleh yang demikian, kajian ini bertujuan untuk menambahbaik sistem CPIS dengan menambah gelembung udara bagi mempercepatkan penginduksian akar pada tunas A. graminifolia. Seterusnya, penggunaan auksin asid naftalenasetik (NAA) dan asid indol-3-butirik (IBA) bagi meningkatkan peratus pengakaran pada tunas A. graminifolia turut dijalankan. Kehadiran gelembung udara di dalam sistem CPIS menunjukkan terdapat peningkatan yang signifikan untuk kelebaran, ketinggian dan kerenggangan mata tunas berbanding dengan CPIS tanpa kehadiran gelembung udara. Tunas yang terhasil dalam sistem CPIS dengan kehadiran gelembung udara juga mampu menghasilkan akar (10% tunas yang berakar) berbanding dengan sistem CPIS tanpa kehadiran gelembung udara yang langsung tidak menghasilkan akar. Penginduksian akar pada tunas A. graminifolia menggunakan IBA dan NAA dengan kepekatan 0, 0.5, 1.0 dan 1.5 ppm menunjukkan perbezaan yang signifikan berbanding kawalan. Penggunaan hormon NAA dengan kepekatan yang semakin meningkat telah meningkatkan purata panjang akar, namun memberi kesan sebaliknya diperhatikan pada rawatan IBA. Kesimpulannya, sistem CPIS dengan kehadiran gelembung udara berserta hormon NAA 1.5 ppm mampu menginduksi dan meningkatkan peratus pengakaran A. graminifolia dengan lebih cepat

Effects of elevated atmospheric CO2 on photosynthesis, growth and biomass in Shorea platycarpa F. Heim (Meranti Paya)

Elevated atmospheric CO2 is widely reported to stimulate the plant growth and affect plant physiological processes. However, studies on the respond of tropical plant species to elevated CO2 are quite limited and remain largely unknown. The objective of this study was to investigate the effects of elevated atmospheric CO2 treatments on the photosynthetic characteristics, growth and biomass in Shorea platycarpa. Saplings of S. platycarpa were grown for seven months in the open roof gas chamber supplied with elevated CO2 (800±50 μmol mol-1) and in the shade house with ambient CO2 (400±50 μmol mol-1). Measurements of S. platycarpa growth and photosynthetic characteristics were made at frequent intervals. Biomass characteristics were determined using destructive methods after seven months of treatment and nondestructive method was used for leaf area index (LAI) determination. Photosynthetic rate (A) of S. platycarpa was not significantly affected by elevated CO2. Increased water use efficiency (WUE) of S. platycarpa grown in elevated CO2 was due to the reduced stomatal conductance (gs) and transpiration rate (E). The CO2 elevation had no significant effect on the S. platycarpa relative growth rates (RGR) and biomass but significantly reduced the leaf area. A weak correlation was found between photosynthetic rate (A) and relative growth rate (RGR). The results clearly showed that photosynthesis, growth rate and biomass of S. platycarpa were not significantly enhanced by elevated CO2. The findings indicated that elevated CO2 did not affect a relatively slow growing and a late successional peat swamp tree species

Temperature Stress on Physiological and Morphological Traits in Rhizophora apiculata

الاحتباس الحراري له تأثيرات كبيرة على النظم البيئية الحيوية، والتي تسببت أيضًا في ارتفاع درجات الحرارة وثاني أكسيد الكربون الذي يتبعه تغيرات في العوامل اللاأحيائية المختلفة، والتي تشكل تهديدات لبيئة غابات المنغروف. تم إجراء هذا البحث لفحص الخصائص الفسيولوجية والمورفولوجية لأشجار القرم Rhizophora apiculata فيما يتعلق بارتفاع درجة حرارة الهواء لأنواع الأشجار المتنوعة التي تستجيب لتغير المناخ. حيث تم زراعة الشتلات لمدة ثلاثة أشهر في غرف نمو منظمة بثلاث درجات حرارة متفاوتة 38 درجة مئوية، 21 درجة مئوية تحت ثاني أكسيد الكربون عند 450 جزء في المليون، والمنطقة المحيط بتركيز ثاني أكسيد الكربون 450 ± 20 جزء في المليون تحت متوسط درجة الحرارة عند 28 درجة مئوية كشرط تحكم. تمت معالجة النباتات كل 48 ساعة بـ 3 لترات من الماء المالح بتركيز 28 جزء من المليون. بعد أسبوعين عند درجة حرارة عالية، أظهرت أشجار المانغروف نتائج إيجابية لجميع المعلمات. أدت التغيرات في درجات الحرارة إلى اختلافات كبيرة، مثلاً سلبية لزيادة درجة الحرارة مما أدى إلى تلف شديد للعديد من العينات بينما كانت إيجابية لانخفاض درجة الحرارة مما أدى إلى نمو بطيء. أظهرت النتائج الفسيولوجية انخفاضًا في معدلات التمثيل الضوئي مقارنةً بالعينات الخاضعة للرقابة. تشير هذه النتائج إلى أن مستويات القدرة على التمثيل الضوئي المنخفضة يمكن أن تكون قد حدثت بسبب انخفاض آلية تفاعل تثبيت ثاني أكسيد الكربون، ومواد أصباغ التمثيل الضوئي، والتباين بين معدل التنفس والتمثيل الضوئي.Global warming has had considerable effects on vital ecosystems, which has also been caused by increased temperatures and CO2 that follow changes in different abiotic factors, which poses threats to mangrove forests environment. This research was conducted to examine the physiological and morphological characteristics of the Rhizophora apiculata mangrove regarding higher air temperature for the variety of tree species that respond to climate change. Seedlings were cultivated for three months in regulated growth chambers with three varying temperatures of 38°C, 21°C under CO2 at 450 ppm, and ambient CO2 concentration i.e., 450 ± 20 ppm under average temperature at 28°C as the control condition. The plants were treated every 48 hours with 3 L of saline water of 28 ppt. After two weeks at high temperature, the mangrove showed positive results for all parameters. The temperature variations resulted in major variations, such as negative for increased temperature resulting in extreme damage to many samples while positive for decreased temperature resulting in slow development. The physiological results show decreased photosynthesis rates compared to controlled samples. These findings indicate that low photosynthetic capability levels could have occurred due to reduced CO2 fixative reaction mechanism, photosynthetic pigment material, and the discrepancy between respiratory and photosynthesis rate

Effects of drought stress on growth and physiological characteristics of roselle (Hibiscus sabdariffa L.)

Drought is the major abiotic stress which causes major losses to agriculture production. This study was conducted to determine the effect of drought stress on the growth and physiological characteristics of Hibiscus sabdariffa. The drought stress treatments were 33, 67 and 100% of the field capacity. Each treatment was replicated five times in a randomized complete block design. According to the results, drought stress had significant effects on the growth and physiological traits of H. sabdariffa. As the drought stress increased, the plant height, leaf area, specific leaf area, fresh and dry weight of shoot and root, photosynthetic rate, stomatal conductance, intercellular CO2 concentration and the transpiration rate decreased. The root-shoot ratio was significantly increased in stressed plants. The changes in number of branches per plant and chlorophyll content were, however, not significant. These findings suggested that H. sabdariffa might be able to tolerate drought stress by increasing the root-shoot ratio and stability of chlorophyll content

Molecular cloning, characterization and expression pattern analysis of a jasmonic acid responsive sesquiterpene synthase gene from Persicaria minor

Abstract Terpenoids represent an important class of plant secondary metabolites, serving as component of plant defense against various biotic and abiotic stresses. A large number of structurally diverse terpenoid compounds have been identified from Persicaria minor (P. minor), an aromatic plant native to Malaysia. However, number of studies focusing on the P. minor terpenoid metabolism, especially at the genetic level is still very scarce. In the present study, a cDNA sequence (KT192706) from the leaves of P. minor, encoding a sesquiterpene synthase (PmSS) gene was successfully cloned. The complete sequence of PmSS comprised of 1724 bp with a 1680 bp open reading frame, corresponding to a deduced protein of 559 amino acids. Under the normal conditions, PmSS gene was found to be differentially expressed in the organs of P. minor. Significantly higher expression level of PmSS was recorded in leaves and stems which are, respectively, about 98 folds and 49 folds higher than that in the roots. In addition, the present study has also shown that the expression of PmSS gene was responsive towards the exogenous application of jasmonic acid in all organs of the P. minor

Isoprene hotspots at the Western Coast of Antarctic Peninsula during MASEC′16

Isoprene (C5H8) plays an important role in the formation of surface ozone (O3) and the secondary organic aerosol (SOA) which contributed to the climate change. This study aims to determine hourly distribution of tropospheric isoprene over the Western Coast of Antarctic Peninsula (WCAP) during the Malaysian Antarctic Scientific Expedition Cruise 2016 (MASEC′16). In-situ measurements of isoprene were taken using a custom-built gas chromatography with photoionization detector, known as iDirac. Biological parameters such as chlorophyll a (chl-a) and particulate organic carbon (POC) were compared to the in-situ isoprene measurements. Significant positive correlation was observed between isoprene and POC concentrations (r2 = 0.67, p < 0.001), but not between isoprene and chl-a. The hotspots of isoprene over maritime Antarctic were then were investigated using NAME dispersion model reanalysis. Measurements showed that isoprene mixing ratio were the highest over region of King George Island, Deception Island and Booth Island with values of ∼5.0, ∼0.9 and ∼5.2 ppb, respectively. Backward trajectory analysis showed that air masses may have lifted the isoprene emitted by marine algae. We believe our findings provide valuable data set of isoprene estimation over the under sampled WCAP

Isolation And Characterization Of A Full-Length Knotted Gene From Oil Palm (Elaeis Guineensis Jacq.)

The oil palm is one of the most important commercial oil crops that produces high quality of oil and with it comes an increasing global demand for this crop. The clonal oil palm produced by tissue culture technique provides an opportunity to expand productivity in order to fulfill the vast demand. However a number of reports have documented the occurrence of abnormalities in clonal oil palm such as vegetative abnormalities of tissue-cultured plantlets and also abnormalities of flowers. There has been no fundamental understanding of the cause of these abnormalities. Since the tissues and organs of plants originate fiom apical meristerns, it is worthwhile to study the molecular mechanism underlying organ morphogenesis k m this undifferentiated meristem cells. Within the past several years, there are several lines of evidence indicating that the homeobox genes control pattern formation and morphological structure determinations in multicellular eukaryotes including plants. In this study, Knotted homeobox gene was identified and isolated in order to develop an understanding of the function of this gene during oil palm development. In order to isolate the fiill-length Knotted homcobox gene from oil palm, an oil palm (Elaeis guineensis Jacq.) suspension culture cDNA library of was screened with a partial cDNA clone (putative oil palm Knotted gene). From the screening, the full-length of oil palm Knotted homeobox gene was isolated and designated as oil galm Knotted homeobox gene (OPKNI). This thesis describes the first homeobox gene isolated from oil palm. Sequence analysis showed that OPKNl belongs to the class-1 Knotted gene family. Expression study by semiquantitative RT-PCR, northern blot as well as in situ hybridization analyses proved that OPKNl gene was expressed in both vegetative and floral meristems suggesting a function in both phases of development. Based on semi-quantitative RT-PCR analyses, OPKNl was shown to be expressed in all meristem-based tissues including shoot apex, both male and female floral meristems, embryogenic callus, and suspension cell cultures. This seems to indicate that OPKNI may play role in meristem organization and later in morphogenesis processes. This can be supported by the presence of OPKNl transcript in leaf prirnordia suggesting that it may play roles in the development of pimate leaf in oil palm. The presence of OPKNl throughout the flower development in both normal and abnormal flowers also indicates that the gene is active during floral development, suggesting a function in floral morphogenesis. Furthermore, the differences in temporal and spatial expression of OPKNl in different stages and type of meristem tissues may cause error in organ determination. ii