Improvements and Evaluation on Bitter Orange Leaves (Citrus aurantium L.) Solar Drying in Humid Climates

Dried, bitter orange leaves are widely used because of their nutritious and medicinal applications. As a result, many technologies have been used to accomplish its drying process. However, drying needs a long time and high energy demand, especially in humid climates. In this paper, bitter orange leaf drying was carried out using thermal and photovoltaic solar energy (integrated system, IS), eliminating the high humidity inside of the drying chamber to improve this process. A regular solar dryer (RD) was also used to compare the kinetics, mathematical modeling, and colorimetry study (as a quality parameter), evaluating both systems’ performances. The drying leaves’ weights were stabilized after 330 min in the RD and after 240 min in the IS, with a maximum drying rate of 0.021 kg water/kg dry matter∙min, reaching a relative humidity of 7.9%. The Page and Modified Page models were the best fitting to experimental results with an Ra2 value of 0.9980. In addition, the colorimetric study showed a better-preserved color using the IS, with an ∆E of 9.12, while in the RD, the ∆E was 20.66. Thus, this system implementation can reduce agroindustry costs by reducing time and energy with a better-quality and sustainable product, avoiding 53.2 kg CO2 emissions to the environment.

PELATIHAN PENGOLAHAN MINYAK JELANTAH MENJADI LILIN AROMA DAUN JERUK UNTUK IBU-IBU PKK KELURAHAN SUNGAI PINANG LUAR SAMARINDA

ABSTRAKPermasalahan utama yang dihadapi oleh pihak kelurahan Sungai Pinang Luar Samarinda adalah penggunaan minyak jelantah yang berulang kali oleh ibu rumah tangga untuk menggoreng makanan dan membuang minyak jelantah tersebut sembarangan. Pengabdiaan ini bertujuan untuk memberikan pemahaman kepada ibu-ibu PKK kelurahan Sungai Pinang Luar Samarinda tentang bahayanya penggunaan minyak jelantah yang digunakan berulangkali bagi kesehatan dan pembuangan minyak jelantah ke lingkungan yang akan mengganggu stabilitas ekologi pada lingkungan tersebut, sehingga dibentuk sebuah upaya tindakan melalui pelatihan pengolahan minyak jelantah menjadi sesuatu yang bernilai ekologis dan ekonomis. Metode yang digunakan dalam pengabdian ini adalah pelatihan langsung kepada ibu-ibu PKK di kelurahan Sungai Pinang Luar dalam pembuatan lilin aroma daun jeruk dari minyak jelantah. Hasil pengabdian ini terlihat antusiasme peserta untuk mencoba membuat sendiri lilin aroma daun jeruk dari minyak jelantah yang digunakan. Kata Kunci: pelatihan; minyak jelantah; lilin aroma daun jeruk. ABSTRACTThe main problem faced by the Sungai Pinang Luar village Samarinda is the repeated use of used cooking oil by housewives to fry food and throw the oil carelessly. This service aims to provide an understanding to PKK women in Sungai Pinang Village, Luar Samarinda about the dangers of using used cooking oil repeatedly for health and the disposal of used cooking oil into the environment which will disrupt the ecological stability of the environment, so that an action effort is formed through oil processing training, waste cooking becomes something of ecological and economic value. The method used in this service is direct training to PKK women in Sungai Pinang Luar village in making orange leaf scented candles from used cooking oil. The results of this service were seen by the enthusiasm of the participants to try to make their own orange leaf scented candles from the used cooking oil.Keywords: training; cooking oil; citrus leaf scented candle.

In vitro biological activity of ethanolic extracts from plants of the Meliaceae family on Diaphorina citri Kuwayama 1908 (Hemiptera: Liviidae)

In vitro effect of ethanolic extracts of Azadirachta indica seeds, Melia azedarach and Swietenia humilis (Meliaceae) were evaluated on the mortality, repellency and oviposition of Diaphorina citri (Hemiptera: Liviidae). Toxicity was determined by the placement of adults and nymphs on orange leaf discs (Citrus sinensis cv. Valencia) previously sprayed or immersed in the treatments. The repellency was estimated through an exposition of adults to the treated leaf, in an experimental arena for 24 h. In order to inhibit oviposition, Murraya paniculata sprouts sprinkled with 2.5 mL of solution were used. The ethanolic extracts from the three meliaceus showed toxicity on nymphs and adults; however, adults evidenced the toxic effect as of 100.0 mg/mL, while nymphs did at 4.10 mg/mL. With a repellent effect, the 100 mg/mL solution stands out, with 82 and 78% for A. indica and S. humilis, respectively; effect associated to the concentration and the time. The oviposition was affected by ethanolic extracts of S. humilis and A. indica at 100.0 mg/mL. It is inferred that the ethanol extracts from S. humilis and A. indica present potential to be considered in the development of alternatives for the integrated management of D. citri.

Geographic Distribution, Genetic Variability and Biological Properties of Rice Orange Leaf Phytoplasma in Southeast Asia

Rice orange leaf phytoplasma (ROLP) causes clear orange to yellowish leaf discoloration and severe stunting in rice seedlings. The ecological and biological characteristics of ROLP are largely unknown because the disease has not widely caused serious problems in rice cultivated areas, thereby leading to the low accumulation of research data. However, in the past decade, the disease became a threat to rice production, particularly in South China and India; it has also been recognised in other Asian countries, such as Vietnam, Thailand and the Philippines. Here, we observed the occurrence of ROLP in paddies of the Southeast Asian counties (Cambodia, Vietnam and the Philippines) and found that the isolates in the Philippines and Vietnam were monophyletic, while those in India, Thailand and Cambodia were more diverse, suggesting their potential origins. In Cambodia, it was revealed that following polymerase chain reaction (PCR) detection, the known ROLP-insect vectors, N. virescens Distant and Recilia dorsalis Motchulsky, were ROLP-positive, indicating their roles in pathogen dispersal. Moreover, fluorescent and scanning electron microscopy revealed the intensive accumulation of the phytoplasma in phloem tissues and massive accumulation of storage starch in vascular bundle sheath and parenchyma. Altogether, this study illustrated the genetic variability of global ROLP isolates and the pathogen’s biological impact on rice tissue.

Development of loop-mediated isothermal amplification (LAMP) assay for detection of Pseudocercospora angolensis in sweet orange

Pseudocercospora angolensis is the causative agent of Pseudocercospora leaf and fruit spot disease in citrus which can result in up to 100% yield loss. Early diagnosis of this disease is vital for effective control. This study aimed at developing a loop-mediated amplification (LAMP) system for detecting P. angolensis in sweet oranges in comparison with Polymerase Chain Reaction (PCR) and using microscopy as a gold standard. Twelve non-target species were used to assess the analytical specificity of LAMP and PCR whereas the analytical sensitivity was determined using serial dilutions of P. angolensis DNA. The diagnostic accuracies of the two assays were evaluated using DNA from 150 diseased and 50 non-diseased sweet orange leaf samples. The analytical sensitivity and detection time of LAMP were of 10−4 ng/ μl and 40 minutes, respectively. The analytical sensitivity of PCR was 10ng/μl and it was specific to P. angolensis whereas three relatives of P. angolensis were detectable by LAMP. The diagnostic sensitivities of LAMP (93%) and microscopy (100%) were significantly different (X2 = 8.38, P = 0.0038) unlike the diagnostic specificities (90%) and (100%), respectively (X2 = 3.37, P = 0.066). Microscopy was significantly more sensitive than PCR (32.6%) (X2 = 149.26, P < 2.2e-16) and equally specific as PCR (P=NA). The positive predictive values of PCR and LAMP were 100% and 96.5% respectively whereas the negative predictive values were 33.1% and 81.8% respectively. The LAMP assay developed in this study offers a great tool for routine screening sweet orange samples for P. angolensis.

Reemerging Rice Orange Leaf Phytoplasma with Varying Symptoms Expressions and Its Transmission by a New Leafhopper Vector—Nephotettix virescens Distant

Rice orange leaf phytoplasma (ROLP) belongs to the “Candidatus Phytoplasma asteris” 16SrI-B subgroup, which is solely transmitted by the zigzag-striped leafhopper (Recilia dorsalis Motchulsky) and the green leafhopper (Nephotettix cincticeps Uhler) (Hemiptera: Cicadellidae). Recently, rice plants showing orange leaf discoloration have become ubiquitous in several paddies of two provinces in the Philippines. In total of 98 symptomatic rice plants, 82% (Laguna) and 95% (Mindanao) were ROLP-positive by nested PCR detection. These plants showed more varying symptoms than previously reported. The vector insect R. dorsalis was scarcely present but green paddy leafhopper, N. virescens Distant (Hemiptera: Cicadellidae), was commonly observed in the paddies, thus the ability of N. virescens to transmit ROLP was thoroughly investigated. Newly emerged adult N. virescens, which fed on ROLD-source rice plants, were used to inoculate a susceptible rice seedling and was serially transferred into a new healthy seedling. Resultant positive transmission rates varied from 5.1% to 17.8%. The transmission ability of the insects was generally decreased over time. These findings suggest that N. virescens is an alternative vector of ROLP in the Philippines. Altogether, this study highlighted the increasing importance of ROLD-reemergence in Southeast and East Asia and proved the need for careful management of this alternative vector insect.

Development of a Specific Polymerase Chain Reaction System for the Detection of Rice Orange Leaf Phytoplasma

Rice orange leaf disease (ROLD), caused by rice orange leaf phytoplasma (ROLP), is transmitted by leafhopper vectors Recilia dorsalis and Nephotettix cinticeps. ROLD severely devastates rice production in Asia. Accurate detection of the pathogen is important for disease management. Current nested polymerase chain reaction (nested PCR) method using phytoplasma universal primers is widely used to detect phytoplasmas; however, it has shortcoming of inconvenience and inaccuracy, for it needs two round of PCR reactions and could produce false positive results due to nontarget amplification. In this study, we developed a PCR assay using a set of primers designed based on the ROLP genome sequence to amplify house-keeping gene FtsH-1 in rice and leafhopper vector samples. This method is simple and rapid, and its sensitivity up to 10 pg/μl of total ROLP DNA. It also minimizes the false positive problem produced by nested PCR. This method was used to survey the geographic distribution of ROLD in southern China from 2016 to 2018. The results showed that the distribution areas and vector carrying rate of ROLD had gradually increased.