Application of Different Rates and Frequencies of Rejuvenator for the Treatments of Brown Bast Syndrome on Hevea brasiliensis

Background: Brown bast is one of the most serious threats to natural rubber production. It is estimated that brown bast leads to an approximately 15-20% decrease in latex yield production. There is currently no effective method to control this problem and an effort to overcome this problem is in progress by the natural rubber producing countries. Methods: This study evaluated the effect and the most suitable rate and frequency of Rejuvenator application to cure brown bast (latex dryness) and improve latex yield. The Rejuvenator treatment was applied to the selected tree with two different treatment frequencies (every 3 days and every 6 days) and three different Rejuvenator concentrations (5 g/L, 10 g/L and 5 g/L). The Rejuvenator was applied 5 times. Data on latex yield and brown bast cure were then recorded 1 month after the application of the last treatment. The treatments used were T1: No Rejuvenator, T2: 5 g/L of Rejuvenator, T3: 10 g/L of Rejuvenator, T4: 15 g/L of Rejuvenator. Result: Of all the treatment used, T3 (10 g/L) resulted in higher production of latex yield and Hevea bark nutrient concentration (g/t/t) than control. It also gave the highest nutrient content in the bark tissue. The findings of this study reveal that the optimum concentration and frequency of Rejuvenator application were established at 10 g/L every 6 days. More so, the findings explain that inadequate nutrients can be attributed to the brown bast syndrome in rubber plantation which can be prevented with the use of a rejuvenator to the tree’s bark.

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 different inoculum levels of P. arborescens in disease development and yield losses of opium poppy

Downy mildew (DM) caused by Peronospora arborescens is the most alarming disease of opium poppy which hampered the production of opium crop in major growing areas of India. The pooled data taken from Rabi 2016-17 and 2017-18 demonstrated that chemical protected un-inoculated plot had a minimum per cent disease severity (9.83) with maximum dry latex yield (31.25 kg ha-1), seed yield (801.31 kg ha-1) and husk yield (889.66 kg ha-1). However, plots inoculated with Peronospora arborescens at high inoculum density of 9×105 spores ml-1 had considerably higher per cent disease severity (67.00) and minimum dry latex yield (6.94 kg ha-1), seed yield (548.42 kg ha-1) and husk yield (590.86 kg ha-1) with maximum 77.79,31.56 and 33.58 per cent loss as compared to un-inoculated chemical protected plot, respectively. The severity of the downy mildew disease was found to rise in direct conflict with the level of inoculum concentration with significant reduction in dry latex yield, seed yield and husk yield.

Latex Diagnosis at the Whole Trunk Level under Different Tapping Systems in Young-tapping Rubber Trees

Background: Numerous rubbers tapping systems have been developed to increase latex yield. The objectives were (i) to test the efficiency of stimulation tapping systems and (ii) to describe the sucrose balance between supply and demand in the latex-producing bark of the rubber tree.Methods: The experiment was conducted at Thepa Research Station in Songkhla province. Eleven-year-old of RRIM600 clone was investigated. The experiment was designed as One Tree Plot Design (OTPD) with 4 tapping systems (Treatment; T) and 4 replications. Treatments were T1: S/3 2d/3, T2: S/6 d3, T3: S/6 d3 with RRIMFLOW and T4: S/6 d3 with LET. Result: S/6 d3 with RRIMFLOW tapping system in young-tapping rubber tree provided significantly highest averaged latex yield per tapping. The average cumulative latex yield was no significant difference comparing with the traditional tapping system. Rubber girth increment had no significant difference among treatments (P greater than 0.05). An averaged sucrose distribution in the trunk level of none stimulation treatments were high to very high sucrose values; however, it was medium sucrose values in the stimulation treatments. Inorganic phosphorus distribution in the trunk level showed medium to high values. Hence, the finding indicated that the use of ethylene stimulation together with tapping system should be considered for rubber tree and to control the balance of sucrose content in the trunk level of rubber tree.

Influence of Bioregulators on Latex Yield and Proteolytic Activity of Papain Extracted from Field-grown TNAU Papaya CO. 8 under the Natural Incidence of Papaya Ring Spot Virus

The cultivation of papaya for both fruits and commercial papain extraction drastically suffers often due to the devastating incidence of papaya ringspot virus disease. The present study aimed to find out whether the papain yield and quality are influenced when bioregulators are applied to manage papaya ring spot virus (PRSV) incidence or as a measure to limit the height of the crop in TNAU Papaya CO.8 variety grown in the open field with the natural incidence of PRSV. Three growth retardants [250 ppm of prohexadione calcium (G2), 500 ppm of mepiquat chloride (G3) and 500 ppm of chlormequat chloride (G4)] and three stress tolerance promoting bioregulators [100 ppm of methyl jasmonate (S2), 100 ppm of salicylic acid (S3) and 0.6 g/ l of strobilurins (S4)] were employed in the study. Water spray (G1 and S1) was kept as control. The treatments were imposed at 4th and 8th months after planting. The growth retardants were initially sprayed and, in the subsequentweek ,the stress tolerance promoting bioregulators were sprayed as per the recommended doses. Among the combinations tried, spraying 250 ppm of prohexadione calcium followed by water spray (G2S1) a week later recorded the lowest plant height (140.79 cm) at the time of fruiting. The treatment combination G 2S2 involving 250 ppm of prohexadione calcium and 100 ppm of methyl jasmonate registered a higher number of fruits (42.17). The combination of 250 ppm of prohexadione calcium along with 100 ppm of salicylic acid (G2S3) was found to be the most effective combination to manage PRSV without compromising papain production and to enhance the proteolytic activity significantly (44378.36 TU g-1) as compared to other combinations. The treatment combination of 500 ppm of mepiquat chloride and 100 ppm of salicylic acid (G3S3) favored higher dry latex yield apart from a significant reduction in PRSV symptoms. Both these treatment combinations (G2S3 and G 3S3) merit due consideration in PRSV management for commercial fruit and papain production in papaya

A review: The development of double row spacing to improve land productivity and income of rubber smallholders

Low prices of rubber has been a serious problem to rubber smallholders in Indonesia. Rubber-based intercropping systems offers a practical solution to this issue and increasing overall productivity of intercrops, for example upland rice and maize. This study reviewed the suitable spatial arrangements in rubber planting to long term impact based intercropping systems. A field experiment was established in a smallholder rubber plantation in Tanah Laut Regency, South Kalimantan with area of 50 ha. Two planting patterns of rubber PB 260 clone were tested: (1) single row planting pattern (SR) by 6 m x 3 m, and (2) double row planting pattern (DR) by 18 m x 2 m x 2.5 m. The experiment showed that girth of rubber trees in the SR system at the first tapping year was slightly larger than in DR system, even though statistically it was not significant. The latex yield per tree of SR and DR systems were similar, however, latex yield per hectare of SR system was higher than DR system due to a higher tree population in SR system. The DR system was technically suitable for long term intercropping, because when rubber tree can reached 8 to 9 years old and light penetration was more than 80% at distance from the rubber row. The total area required for rubber, upland rice and maize grown in monoculture to produce an equivalent of a one hectare of rubber-upland rice-maize intercrop is 1.87. This means the intercropping has an advantage compared to monoculture.

Effect of high-frequency tapping system on latex yield, tapping panel dryness, and biochemistry of young hillside tapping rubber

The objective of this study was to examine the effect of high-frequency tapping system (1/3S 3d/4) on latex yield, biochemistry and its impact on the Tapping Panel Dryness (TPD) of young RRIM600 hillside tapping rubber. The experiment was conducted at three different hillside rubber plantations (NM 1 - 3) at Na-Mom district, Song Khla province, Thailand. Eight-year-old rubber RRIM 600 clones was used in the experiment starting from 2008 until 2009. The rubber trees were investigated for latex yield production, bark consumption, and TPD. In addition, latex diagnosis (sucrose, inorganic phosphorus (Pi), and thiol levels) was measured. The results demonstrated that high-frequency tapping system positively affected the rubber latex yield formation. However, site-specific condition of rubber plantation altered latex yield production. NM 3 provided the highest latex yield (fresh and dry weight) as compared to other plantations. Tapping frequency was highly correlated to latex yield (fresh and dry weights) in all investigated rubber plantations (R2 > 0.75). Using high-frequency tapping system increased bark consumption and stimulated TPD. Moreover, results of latex diagnosis (sucrose, Pi, and thiol levels) showed relatively unhealthy rubber tree as impacted by high-frequency tapping system. Therefore, the farmer should consider it for better decision-making for tapping system application.

Effect of low-frequency tapping systems (d5; d6) on latex yield, labor productivity and latex physiological parameters on RRIV 106 clone

The tapping labor shortage has been identified as a major issue for natural rubber companies in Vietnam. This study aimed to determine a suitable tapping system to adapt to the labor shortage. The experiment was conducted on RRIV 106 clone at Dong Phu rubber company, Binh Phuoc province, Vietnam in two the tapping years 2018 and 2019. The results showed that the treatments of low-frequency tapping systems (d5, d6) increased individual yield per tree per tapping (g/t/t) compared with that of d4. The g/t/t of treatments d5 and d6 with latex stimulant (ET 2.5%) applied by 6 to 10 times per year (d5, ET.6/y; d5, ET.8/y; d6, ET.8/y; d6, ET.10/y) was 23; 27; 45 and 47% higher than that of the control (d4, ET.4/y), respectively. Labor productivity (kg/task/day) of low-frequency tapping systems increased similarly to g/t/t. The tapper requirements of low tapping frequency (d5 and d6) were 20% and 33% lower than that of d4, respectively. Land productivity per year (kg/ha/year) of low-frequency tapping systems (d5 and d6) was equivalent (98 to 101%) as compared with that of the control. The effects of tapping systems on latex physiological parameters, tapping panel dryness rate (TPD), and dry rubber content (DRC, %) were not significantly different.