APPLICATION OF Trichoderma spp. AND LIGNOHUMATE TO SUPPRESS A PATHOGEN OF CLUBROOT (Plasmodiophora brassicae WOR.) AND PROMOTE PLANT GROWTH OF CABBAGE

The high economic value of cabbage crop leads farmers to make various efforts to suppress the pathogen of club root which is detrimental to plants. Efforts that need to be put forward must be environmentally safe. One way that is environmentally friendly is to control a pathogen biologically using antagonistic microbes. Therefore, the use of microbes such as Trichoderma which has been widely studied is important because it was able to suppress clubroot incidence and stimulate plant growth as well. Meanwhile, the need for plant nutrients to maximize plant growth requires an input of organic materials such as lignohumate which preserve soil nutrients, improve soil structure and increase plant resistance to biotic and abiotic stresses. The previous study on this scheme found an effective indigenous Trichoderma to suppress clubroot, therefore it is used in the current study. The objective of this study was to find out a combination treatment of Trichoderma and lignohumate which can suppress clubroot and increase plant growth. This experiment used a Randomized Block Design with 2 factors and 3 replications. Trichoderma concentration consisted of 3 levels, namely 0 spores (control), 1x106 spores. 2x106 spores, and 3x106 spores per plant which were suspended in 150 ml of water. The lignohumate treatments were 0.01, 0.02, 0.05, 0.1, 0.5, 1.0, and 2%. The results showed that lignohumate treatment was interact with Trichoderma population number on disease incidence, total clubroot, root dry weight, but not to canopy dry weight. The most suitable combination of treatments was the Trichoderma population of 3x106 spores (15 g) in combination to lignohumate of 0.5%.  This combination resulted in the lowest disease incidence, the lowest total clubroot, root dry weight, and the highest canopy dry weight. The higher the lignohumate concentration up to 0.5%, the higher the number of microbes (fungi and bacteria) growth, howeverit decreased above the concentration of 0.5%.

The clubroot can grow big enough to restrict the xylem tissue inhibiting efficient water uptake by the plant. Galls appear like clubs or spindles on the roots. Eventually the roots will rot and the plant will die. Gall formation or distortion takes place on latent roots and gives the shape of a club or spindle.
In the cabbage such attacks on the roots cause undeveloped heads or a failure to head at all, followed often by decline in vigor or by death. It is an important disease, affecting an estimated 10% of the total cultured area worldwide.  (Punja and Utkhede, 2003;Tian et al., 2007).
Humic substances based amendments as fertilizers have been increased in recent years and proven increase plant yield.
Lignohumate (LH) is one of humic sources commercially is used widely in agriculture for many crops and various conditions. The advantage of LH is preserve nutrients of leaching, improve soil structure, and increase plant resistance to biotic and abiotic stresses.
The previous year's study on this scheme have been found an effective indigenous Trichoderma to suppress clubroot and would be used in this study. The purpose of this study was to obtain the best combination treatment of Trichoderma and LH which able to suppress clubroot and also increase plant growth.

Treatments
The treatments tested in this experiment was population of Trichoderma as biocontrol agent in combination with doses of humic product Lignohumate (LH).
The treatments were set according to a

Inoculum preparation
T. asperellum pure culture were inoculated into half-cooked rice aseptically.
A half kilogram of the rice was put into plastic bag and shaking, then incubated for a week. When the blue colour appear on all around the rice, then the spores formed in it was measured by haemacytometer. In this research the amount of spores in one gram of the rice media was equals to 1 x 10 6 spores.

Seedling preparation
Cabbage seedling are prepared by means of seeds sowed on beds made of bamboo blades with a soil-humus mixture of 1:1 ratio. The beds are watered just enough everyday and after the seedling have grown and was 7 days old, the seedlings were ochered (soil fist at the root) and after 14 days were ready to be replanted to the field and arranged in a distance of 50 cm x 50 cm in a plot sized of 100 cm x 1200 cm.

Statistical analyses
The data were variant analysed according to the randomized complete design using the Microsoft Excel software. When the difference between the treatments was significant, this differences were compared by Duncan Multiple Range Test on level of 1 and 5%.

Root dry weight
High root dry weight was a result of the formation of high root cell volumes that occur due to root cell division which influenced by of the pathogen P. brassicae.
When the pathogen interacts with its host, auxin will soon formed in plant cells, resulting in uncontrolled root cell division and tumor formation. High root dry weight indicates that the treatment is ineffective as in control. So the lower the dry weight of the root (to a certain extent), the more effective the treatment. Effective treatment of pressing clubroot according to low root dry weight and the most effective treatment was 0.5% LH dose combination with Trichoderma concentration of 3x10 6 (15 g) which produced 3.8 g of root dry weight.

Canopy dry weight, leaf area, and chlorophyll content
The highest canopy dry weight also occurs at 0.5% LH concentration in the entire Trichoderma population (Fig. 2) and also the largest leaf area occurred at the lignohumate dose (Fig. 3). The highest chlorophyll amount achieved was 7400.77 SPAD at the same lignohumate dose which was higher than that at 1.0% (Figure 4) which the amount of Trichoderma 3x10 6 CFU (15 g).

Fig. 2. Canopy dry weight under LH concentration and total Trichoderma spores.
The highest dry weight canopy occurred at 0.5% LH concentration and the lowest was in the control treatment (Fig. 2).
This showed that LH has an active role in increasing soil fertility, increasing nutrient uptake, and also increasing the amount of chlorophyll, all of which will produce high photosynthetic products that were expressed in the high dry weight of plants.

Microbial population
Humic substances are showed to increase soil biological activity, and this is considered to be one of the probable mechanisms of their positive effect on plant growth and development. This is true for humic-based product LH as well. Table 4 shows   (Karakurt et al., 2009) and chrysanthemum (Fan et al., 2014). More over, according to Ertani et al. (2011) andPoloskin et al. (2012), LH has been shown to increase chlorophyll production. High chlorophyll has more implications for more photosynthesis which results in the formation of more carbohydrate products which means the dry weight of plants will be greater than without LH.