HbSnRK2.6 Functions in ABA-Regulated Cold Stress Response by Promoting HbICE2 Transcriptional Activity in Hevea brasiliensis

Low temperature remarkably limits rubber tree (Hevea brasiliensis Muell. Arg.) growth, latex production, and geographical distribution, but the underlying mechanisms of Hevea brasiliensis cold stress response remain elusive. Here, we identified HbSnRK2.6 as a key component in ABA signaling functions in phytohormone abscisic acid (ABA)-regulated cold stress response in Hevea brasiliensis. Exogenous application of ABA enhances Hevea brasiliensis cold tolerance. Cold-regulated (COR) genes in the CBF pathway are upregulated by ABA. Transcript levels of all five HbSnRK2.6 members are significantly induced by cold, while HbSnRK2.6A, HbSnRK2.6B, and HbSnRK2.6C can be further activated by ABA under cold conditions. Additionally, HbSnRK2.6s are localized in the cytoplasm and nucleus, and can physically interact with HbICE2, a crucial positive regulator in the cold signaling pathway. Overexpression of HbSnRK2.6A or HbSnRK2.6B in Arabidopsis extensively enhances plant responses to ABA and expression of COR genes, leading to increased cold stress tolerance. Furthermore, HbSnRK2.6A and HbSnRK2.6B can promote transcriptional activity of HbICE2, thus, increasing the expression of HbCBF1. Taken together, we demonstrate that HbSnRK2.6s are involved in ABA-regulated cold stress response in Hevea brasiliensis by regulating transcriptional activity of HbICE2.

DAMPAK TEKNIK SADAP SPIRAL TERHADAP PENERIMAAN PETANI KARET DI KABUPATEN TANJUNG JABUNG TIMUR

One of the way to increase rubber productivity and its production, is by focusing to recommended tapping techniques. In East Tanjung Jabung Regency although the recommended rubber tapping technique (i.e. spiral tapping technique) had been socialized, but there were still many rubber farmers who done a non-spiral tapping techniques. This will certainly affect the amount of latex production and the rubber plants life duration. The low amount of rubber production will lead to a low number of sales, so it will have an impact on the low revenue of rubber farmers. The purpose of this study was to find out the impact of the application of spiral tapping techniques on rubber crops toward farmer. The results showed that simultaneously the independent variables had a Significant effect on the Farmer revenues. Partially, rubber production and rubber prices had showed a significant effect on farmer’s revenues, while the age of crops and tapping techniques, had no significant effect on the farmer’s revenues. Although the variables of tapping techniques did not significantly effect to the farmer revenue but it gave the higher revenue than the other tapping techniques.

Respons fisiologi dan hasil lateks tanaman karet klon GT 1 di kebun karet rakyat terhadap sistem eksploitasi dan curah hujan

AbstrakKlon GT 1 adalah klon Slow Starter (SS) dimana perubahan sukrosa menjadi partikel karet di dalam pembuluh lateks berlangsung lambat dan pada saat gugur daun hasil lateks lebih stabil. Penelitian ini bertujuan untuk mengetahui hubungan curah hujan dan sistem eksploitasi terhadap fisiologi dan hasil lateks klon GT1. Penelitian dilaksanakan di Kabupaten Langkat Kecamatan Besitang Sumatera Utara, ketinggian tempat 500 – 700 m di atas permukaan laut. Analisa fisiologi lateks di PT. Sucofindo Indonesia. Tanaman yang digunakan adalah klon GT 1 umur 25 tahun dengan besar lilit batang antara 60 – 75 cm, diukur dengan ketinggian 130 cm dari permukaan tanah. Metode percobaan menggunakan Rancangan Split Plot. Petak utama adalah panjang alur sadap, terdiri dari tiga taraf, yaitu panjang alur sadap 1/4 spiral, panjang alur sadap 1/2 spiral, dan panjang alur sadap 1/8 spiral. Anak petak adalah aplikasi stimulan, terdiri dari dua taraf, yaitu stimulan cair dan stimulan gas. Semua perlakuan diulang tiga kali. Hasil penelitian menunjukkan bahwa panjang alur sadap pendek dan aplikasi stimulan cair memiliki kadar sukrosa lateks tinggi . Aplikasi stimulan gas menunjukkan kadar sukrosa lateks yang tinggi pada panjang alur sadap panjang. Kadar tiol belum menunjukkan tingkat stress pada klon GT 1 dapat terlihat dari kadar tiolnya berkisar 0,84 – 1,10 mM. Produksi lateks klon GT 1 lebih dipengaruhi oleh sistem ekploitasi daripada curah hujan.Kata Kunci: fisiologi lateks, Hevea brasiliensis, klon GT 1, slow starterAbstractGT 1 is a Slow Starter (SS) clone where the change of sucrose into rubber particles in the latex vessels is slow, and at the time of leaves fall, the latex yield is more stable. This study aimed to determine the relationship between agro-climate and exploitation system on the physiology and yield of latex clone GT1. The research was carried out in Langkat, Besitang, North Sumatra, at an altitude of 500 – 700 m above sea level. Physiological traits analysis of latex was conducted at PT. Sucofindo Indonesia. The plant used was a 25 years old GT 1 clone with a trunk circumference of 60 – 75 cm, measured at the height of 130 cm from the ground. The research method used Split Plot. The main plot was length of tapping path, consisted of 1/4, 1/2, and 1/8 spiral tapping groove length. The subplot was stimulant application, consisted of liquid and gas stimulant. The results showed that short tapping groove length and liquid stimulant application had high latex sucrose content, as given by long tapping groove length and gas stimulant application. Thiol level did not show the stress level in the GT 1 clone, it could be seen from the thiol level of 0.84 – 1.10 mM. Latex production of GT 1 clones was more influenced by the exploitation system than by rainfall.Keywords: GT 1 clone, Hevea brasiliensis, latex phyisiology, slow starter

Effect of three composts with active ingredients of Pseudomonas fluorescens on the development of white root disease and production of rubber plants

Damiri N, Rofiqi R, Mulawarnam, Rahim SE, Febyanti TP. 2021. Effect of three composts with active ingredients of Pseudomonas fluorescens on the development of white root disease and production of rubber plants. Biodiversitas 22: 3237-3242. White root disease (WRD) caused by Rigidoporus lignosus is a very dangerous disease and a scourge for rubber farmers because it can result in decreased production and kill rubber plants. This research was conducted to observe the impact of compost enriched with the biological agent Pseudomonas fluorescens on the development of white root disease and production in rubber plants. The results showed that the application of compost with active ingredient of P. fluorescens isolates A and B reduced the severity of white root disease in plants with mild, moderate and severe infections, 34.12%, 29.31% and 57.21% respectively. Application of compost with P. fluorescens isolates A and B, either singly or in combination, can increase latex production. The treatment of giving compost enriched with P. fluorescens isolates AR and ABR on rubber plants infected with mild WRD resulted in the highest latex production of 406 gm and 402.74 gm per plant, respectively. These two treatments did not differ from each other but were significantly different from the other treatments and controls.

Correction to: Characterization of a vacuolar sucrose transporter, HbSUT5, from Hevea brasiliensis: involvement in latex production through regulation of intracellular sucrose transport in the bark and laticifers

An amendment to this paper has been published and can be accessed via the original article.

PENGARUH KELAS UMUR TERHADAP PRODUKTIVITAS GETAH POHON PINUS MERKUSII DI KPH BANDUNG UTARA

This research was carried out in RPH Ujung Berung, BKPH Manglayang Barat KPH Bandung Utara, and Divisi Regional Jawa Barat & Banten. The time of the research was conducted from September to November 2018. The purpose of this study was to determine the effect the effect of age classes, diameter difference and interaction between age and diameter. Based on the results of the research it can be concluded that the productivity of pine resin is affected by the age class. It showed by data increased in age class followed by increased productivity of resin. Age Class IV is 13.26 grams, Age Class V is 30.74 grams and Age Class VI is 61.17 grams. There is a tendency for latex production to increase by the time the tree grow older to a certain age. Diameter affect the productivity of resin, the greater the growth of tree diameter, the more abundant the resin can be and the production of pine resin will increase. This is shown by data increased in diameter followed by increasing resin productivity, in diameters of 20-23 productivity of resin is 29.7 grams, diameter 24-27 productivity of resin is 36.44 grams and diameter 28-31 productivity of resin is 38.95 grams. Age classes difference affect the amount of resin production, the older the tree ages, the larger diameter will be, and finally affect to resin productivity, up to a certain age limit.

Land elevation and slope exposition impacts on rubber wood production volume under agroforestry system

As the senile phase due and causes depeleting latex productivity, the rubberwood stands can still be claimed as carbon sequestration under the REDD+ Scheme. This is also to maintain vegetation cover in protected forests, beside for fostering social forestry (HKm) sustainability as well. Nowadays the role of genetic and environment factors on latex production have widely revealed by some researchers, but lack on wood production especially for the effect of land elevation and slope exposition against solar beam radiation so need to research. Ordinary Least Square employed at 95% significant level, the respond variable was the volume wood production per tree, whereas the predictor were land elevation in an-100 m above sea level, land slope expositions that were decomposed into 4 categories with the reference of the compass direction in between 3370.30’ to 225.50 follow needle clock’s direction while the three other directions were the westward, southwest ward, and northwest ward. Air humidity and temperature also incorporated to control model error. Data collected by surveying to 75 parcels at HKm area Mangga Joyo located in Way Kanan Regency. Parameter optimization used Minitab 16. The result suggest that wood volume average: (1) increase significantly by 0.02205m3 for every 100m higher elevation, but (2) decrease significantly by 0.21532 m3 which for westward land exposition compare to the eastward one.

Quasi-static and fatigue performance of bonded acetylated rubberwood (Hevea brasiliensis, Müll. Arg.)

Rubberwood is widely planted for latex production. At the cessation of latex yield it becomes a viable timber source in the wood industry. While good bonding performance of rubberwood has been reported, quantitative information to support this statement is missing. In this study, the tensile shear strength (TSS) and wood failure percentage (WFP) of unmodified and acetylated rubberwood in both wet and dry conditions were examined. Three frequently used adhesives were selected: one-component polyurethane (1C PUR), melamine-urea-formaldehyde (MUF), and phenol-resorcinol-formaldehyde (PRF). Furthermore, fatigue behaviour was analysed for PRF-bonded samples by cyclic loading. Results showed that in dry state, the TSS and WFP of acetylated rubberwood is comparable to the unmodified samples for all adhesives. In wet condition, the performance of bonded rubberwood was improved by acetylation. Cyclic loading revealed comparable fatigue behaviour of bonded unmodified and acetylated rubberwood. This investigation provides first quantitative information on the performance of bonded rubberwood, which can be a valuable input for the production of laminated timber products for structural purposes.

Biofuel, Bioenergy and Feed Valorization of By-Products and Residues from Hevea brasiliensis Cultivation to Enhance Sustainability

In the latex production chain, rubber tree seeds (Hevea brasiliensis) represent an underutilized fraction with high potentialities, which can increase the sustainability of the whole process if rightly valorized. In the present study, the quality of all the fractions obtained from the rubber fruit were evaluated, with the aim to identify possible applications for their valorization with a circular economy perspective. Seeds from five different varieties of rubber tree were analyzed. Furthermore, a whole mass and energy balance was defined, which has allowed us to define hypothetical production scenarios. The obtained results show negligible differences among varieties. Shells and capsules have shown a composition similar to woody biomass, with high heating values (more than 16.5 MJ kg−1), low nitrogen content (below 0.5% on weight basis (w/w)) and reduced ash content (0.51% w/w and 1.90% w/w, respectively). Kernels were chemically extracted comparing two different solvents: n-hexane and ethanol. Both solvents showed similar extraction yields, i.e., 49% w/w and 46% w/w for n-hexane and ethanol, respectively. The resulting extraction flour was characterized by a high protein content (around 40% w/w) making it suitable for animal feeding. The rubber seed oil could be used in blends of different vegetable oils for biodiesel production. All this information is useful for improving the sustainability of the latex production chain and to assess the sustainability of possible bioenergy value chains.