This research aimed to determine the best land and water management by arrangement of plant spacing, irrigation, and drainage of rubber plantation in order to improve rubber plantation productivity. This research was done using The WaNuLCAS (Water, Nutrient and Light Capture in Agroforestry System) model to determine the best land and water management under several scenario combinations of two factors. The first factor was rubber plant spacing arrangement system, which consisted of three levels, i.e. single row (3 x 7 m), single row (3 x 6 m) and double row (2 x 6 x 14 m). The second factor was water management treatment, which consisted of four levels, i.e. without irrigation and drainage, irrigation in dry season, drainage in wet season, and irrigation and drainage in dry and wet season respectively. The results showed that drainage treatment could enhance rubber plantation productivity. Moreover, rubber plantations which were using single row (3 x 7 m), single row (3 x 6 m) and double row (2 x 6 x 14 m) had no significant difference on latex production per hectare.

AbstrakCurah hujan berpengaruh terhadap ketersediaan air tanah. Pada waktu musim kemarau curah hujan menurun sehingga air menjadi faktor pembatas bagi pertumbuhan t a n a m a n k a r e t . D e n g a n a d a n y a keterbatasan air pada waktu musim k e m a r a u t e r s e b u t t a n a m a n k a r e t melakukan adaptasi untuk mengurangi transpirasi dengan cara menggugurkan daunnya. Beberapa jenis klon karet memiliki tipe yang berbeda-beda dalam menggugurkan daunnya karena adanya defisit air dalam tanah, yaitu klon karet yang serentak maupun yang bertahap dalam menggugurkan daunnya pada waktu musim kemarau.

Article history

The best rubber planting materials are needed to build the best rubber plantation. Humic acids could be used to improve the growth of rubber planting materials. Humic acid plays a role as a hormone-like substance. This research was aimed to determine the optimal concentration of foliar application of humic acid in order to enhance the growth of rubber tree planting materials. This research was arranged in a completely randomized block design with five treatments and four replicates. The treatments were the concentrations of humic acids, i.e. 0; 250; 500; 750; and 1,000 ppm. Observations were made on rubber tree diameter, plant height, shoot and root biomass, and nutrient content of leaves and the stem. The results showed that foliar application of 1,000 ppm of humic acids could enhance the growth of rubber tree planting materials. Foliar application of 500 -1,000 ppm of humic acids could increase K content of the stem. The effects of foliar application of humic acids were more apparent in the root part than in the shoot part.

Rubber is one of the economically important tropical trees that produces natural rubber, an essential industrial raw material in Indonesia. In general, rubber can grow well in areas with 1,500 - 3,000 mm rainfall per year that evenly distributed round the year. During the dry season, water availability is reduced so that water becomes a limiting factor for the growth and production of the rubber tree. This paper aimed to determine minimum soil water content that must be maintained to prevent the reduction of PB 260 rubber production based on field water balance. This research was carried out at the Indonesian Rubber Research Institute Experimental Field, South Sumatra, Indonesia, between 2014 to 2019. This experiment used PB 260 clone which was planted in 2001 using a 6 x 3 m plant spacing. Soil analysis showed that the Sembawa had a clay loam soil texture. The measured parameters were latex production (kg per ha per year), rainfall, and evapotranspiration (mm). The results from our six years of study showed that rubber production always decreased when soil water content started to decline below field capacity (33.7 %, or equal to 337 mm with 1m depth of root zone).