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ANALYSIS OF PHENOTYPIC DIVERSITY OF SELECTED HEVEA ACCESSIONS FROM IRRDB 1981 GERMPLASM COLLECTION CONSERVED IN SRI LANKA
No full textPresent study was undertaken to estimate morphological diversity of some accessions from IRRDB 1981 Hevea germplasm collection conserved in Sri Lanka to determine the importance of morphological descriptors in categorizing different accessions in to discrete groups. 13 accessions and clone RRISL 203 were characterized using 14 standardized morphological descriptors. Principal Component Analysis (PCA) showed that the all descriptors were informative and contributes significantly to the variation. First 6 Principal Component scores (PCs) accounted for 88% of the total variation. The cluster analysis based on significant PCs grouped all accessions and RRISL 203 in to 4 main clusters at the distance of 1. Four accessions had more than 1 RMS distance, representing a higher phenotypic variation. RRISL 203 has showed lowest distance (0.12). This study permits the characterization of Hevea accessions in to phenotypically diverse groups using morphological descriptors; hence this will be advantageous for production of diverse genotypes during breeding programs to broaden the Hevea gene pool.Keywords: Hevea germplasm, morphological descriptors, phenotypic variatio
DIVERSITY OF COLLETOTRICHUM SPECIES CAUSING ANTHRACNOSE OF RUBBER TREE IN CHINA
No full textWe investigated the phylogenetic diversity of 62 Colletotrichum isolates associated with symptomatic tissues of Hevea brasiliensis from four provinces in China (Hainan, Guangdong, Guangxi and Yunnan). Based on multi-locus (ACT, CHS-1, CAL, GAPDH, GS, ITS, TUB2) phylogenetic analyses and phenotypic characters, 5 species were distinguished, including two well-characterised species (C. fructicola,                     C. siamense), one novel species of C. gloeosporioides species complex (Colletotrichum ledongense), and two novel species of C. acutatum species complex (Colletotrichum bannanense, and Colletotrichum hainanense). Of these, C. acutatum species complex was proved to be the most dominant and probably host specific taxon occurring on Hevea brasiliensis. Keywords: Hevea brasiliensis, anthracnose, phylogenetic diversity, Colletotrichum sp., rubber, leaf fall diseas
EFFECT OF ETHEPHON CONCENTRATION ON RAW RUBBER PROPERTIES OF NATURAL RUBBER; A QUALITATIVE APPROACH
No full textSkilled tapper scarcity has become one of the main constrains in the rubber plantation industry. This is a current and it will be a future challenge faced by natural rubber industry. To overcome this problem low intensity harvesting (LIH) systems with ethephon (2-Chloroethylphosphonic acid) stimulation is widely adopted to reduce the number of tappings per year without the reduction in annual yields. The properties of raw rubber made out of stimulated latex have not been considered when establishing the maximum dose of ethephone to be applied. The present study discusses the magnitude of variations of some selected raw rubber properties which are of commercial significance. Experiments were laid out in completely randomized block design with six treatments and three replications under half spiral based once in three days tapping system (1/2S d3). Results obtained revealed that LIH systems with ethephon stimulation does not have any adverse effect on raw rubber properties and are well below the limits fixed by ISO standard up to 3% ET concentration. However, properties were negatively affected with the application of higher ET concentrations beyond 3%.Keywords:  ethephon concentration, Hevea brasiliensis, raw rubber properties, stimulation
ODOURLESS NATURAL RUBBER COAGULATED BY MICROORGANISM
No full textIn China, SCR WF, produced using fresh latex as raw materials and acid as coagulant, accounts for the main production of commercial technically specified rubber (TSR) grades. Although SCR WF has advantages in price, normally 200 dollars/ ton and higher than TSR20, its mechanical properties such as tensile strength and hardness are lower compared with TSR20. It has been proved that auto-coagulation endows better mechanical properties to rubber than acid coagulation. However, this auto-coagulation process causes a malodorous effect to the rubber and the generated serum, which severely affects the health of workers in the factory and members of the public who live around. In this study, we report a new microorganism coagulation technique which can fully coagulate the field latex, preserved with or without ammonia, within 24 hours by the microbial strain from targeting cultivation. Moreover, this technique causes no unpleasant odour to the rubber and the wastewater, which shows a green characteristic for natural rubber processing. The mechanical properties were also evaluated and the results show that the produced rubber possesses a higher tensile strength and better dynamic properties than the control (SCR WF).Keywords: natural rubber, odourless, coagulation, microorganism, latex, serum, TSR, SCR WF, coagulatio
KONTRIBUSI TENAGA WANITA TERHADAP KESEJAHTERAAN KELUARGA PETANI KARET (STUDI KASUS DI KEBUN PERCOBAAN BALAI PENELITIAN SEMBAWA, KABUPATEN BANYUASIN, SUMATERA SELATAN)
No full textHarga karet yang tidak stabil berdampak kepada pendapatan keluarga petani karet. Oleh karena itu, upaya meningkatkan kesejahteraan keluarga diperlukan sumber pendapatan lain, salah satunya dengan memberdayakan tenaga kerja wanita untuk meningkatkan kesejahteraan keluarga. Penelitian ini bertujuan untuk mengukur besarnya kontribusi penyadap wanita terhadap tingkat kesejahteraan keluarga petani karet berdasarkan tingkat pendapatan serta kualitas sadapan yang dihasilkan. Metode penelitian ini menggunakan analisis kualitatif. Pemilihan lokasi dan sampel dilakukan secara purposive dengan pertimbangan lokasi tersebut terdapat penyadap wanita. Data yang digunakan merupakan data primer dan sekunder. Berdasarkan hasil penelitian dapat dijelaskan bahwa penyadap wanita memiliki kontribusi terhadap pendapatan keluarga tani karet sebesar 53%. Curahan tenaga kerja wanita untuk menyadap karet sebesar 31%, bekerja selain menyadap sebesar 9%. Produktivitas tenaga kerja wanita tergolong lebih rendah dibandingkan penyadap laki-laki. Hal tersebut dapat dilihat dari perolehan premi dan produksi yang dihasilkan. Namun, kualitas sadapan yang dihasilkan para penyadap wanita tergolong baik, hal tersebut dapat dilihat dari kedalaman penyadapan dan konsumsi kulit
KARET ALAM EPOKSI SEBAGAI BAHAN BAKU PEMBUATAN KOMPONEN KARET PADA KATUP TABUNG DAN REGULATOR LPG
Get PDFTrend penurunan harga karet alam dalam 5 tahun terakhir mendorong diversifikasi produk berbasis karet alam, salah satunya adalah komponen karet pada katup tabung dan regulator LPG. Pembuatan komponen karet untuk katup dan regulator LPG selama ini masih menggunakan karet sintetis yang memiliki sifat polar. Karet sintetik NBR memiliki ketahanan yang baik terhadap LPG/n-pentana, sedangkan karet alam mudah mengembang dalam minyak. Epoksidasi ikatan rangkap molekul karet alam merupakan upaya untuk meningkatkan polaritasnya, sehingga ketahanannya terhadap minyak serta beberapa sifat fisiknya meningkat. Tujuan dari penelitian ini adalah meningkatkan konsumsi karet alam dengan cara substitusi karet sintetik (NBR) dengan karet alam epoksi. Lateks pekat diencerkan kemudian direaksikan dengan asam performat pada suhu 70 °C selama 5 jam kemudian dinetralkan, digumpalkan, digiling krep, dan dikeringkan. Karet alam epoksi yang diperoleh selanjutnya digunakan untuk formulasi komponen karet pada katup tabung dan regulator gas LPG dan diuji sesuai persyaratan di dalam SNI 7655:2010 tentang rubber seal. Hasil penelitian menunjukkan bahwa kompon berbasis karet alam epoksi memenuhi persyaratan SNI. Dengan demikian karet alam epoksi dapat digunakan sebagai bahan baku pembuatan komponen karet pada katup tabung dan regulator LPG
RESISTENSI TANAMAN KARET KLON IRR SERI 300 TERHADAP PENYAKIT GUGUR DAUN COLLETOTRICHUM DI SUMATERA SELATAN
Get PDFPenyakit gugur daun Colletotrichum merupakan salah satu penyakit penting yang dapat menyebabkan penurunan produksi lateks pada perkebunan karet. Pengendalian penyakit gugur daun Colletotrichum yang paling efektif adalah dengan penggunaan klon resisten. Pengujian resistensi klon karet IRR seri 300 dilakukan di laboratorium dan rumah kaca dengan menggunakan rancangan acak lengkap dua faktor yaitu jenis klon (26 jenis klon) dan isolat C. gloeosporioides (tiga isolat: CG-PR 303, CG-RRIM 600, dan CG-GT 1). Selain itu, pengamatan serangan penyakit secara langsung juga dilakukan pada tanaman belum menghasilkan di lapangan. Hasil pengujian menunjukkan bahwa semua isolat C. gloeosporioides memiliki pengaruh nyata terhadap tingkat ketahanan 22 klon IRR seri 300 baik di laboratorium maupun di rumah kaca. Isolat CG-PR-303 memiliki tingkat virulensi paling tinggi dibandingkan isolat lainnya. Berdasarkan hasil pengamatan pada tiga kegiatan dapat disimpulkan bahwa 13 klon karet yaitu IRR 300, IRR 301, IRR 302, IRR 307, IRR 308, IRR 309, IRR 310, IRR 311, IRR 313, IRR 315, IRR 316, IRR 318, dan IRR 321 memiliki tingkat resistensi yang tinggi terhadap penyakit gugur daun Colletotrichum
COMPARATIVE TRANSCRIPTOME ANALYSIS REVEALS EARLY GENE EXPRESSION PROFILE THAT CONTRIBUTES TO COLD RESISTANCE IN HEVEA BRASILIENSIS (PARA RUBBER TREE)
No full textRubber trees (Hevea brasiliensis) are tropical perennial woody plants that are susceptible to cold stress. In China, cold stress caused severe damages to rubber plantations in the past decades. Though several cold resistant Hevea clones have been bred, their cold hardiness mechanism is yet to be unraveled. In this study, the cold resistant clone CATAS93-114 and sensitive Reken501 were subjected to cold stress and their transcriptomes were analyzed at the time points of 0h, 2h, 8h and 24h. De novo transcriptome assembly and comparison were then carried out. The results showed that there were totally 7870 genes differentially expressed in these clones. The resistant clone CATAS93-114 had more genes being evoked from 2h to 8h during cold treatment, indicating more rapidly and intensively responsive profile than the sensitive clone Reken501. The DE genes can be further classified into seven major clusters, and GO terms in each cluster were enriched. The genes involved in ABA metabolism and signaling, ABA-independent pathway and early signal perception were noteworthy for their distinctive expression patterns toward cold stress between clones. Twenty-two genes playing a central role in these pathways were further investigated, and QPCR analysis of these genes confirmed the RNA-Seq results.Keywords:Â Â cold resistance, Hevea brasiliensis, transcriptome, QPCR, RNA-seq, ABA, rubber, hevea, cold stress, gen