Diversity, Species, and Plant Growth Regulator and Nutrient Content of Local Weeds in Tawaeli Sub-District, Palu City, Indonesia

Indonesia has a high opportunity to develop organic agriculture with the existing potential to be able to increase the production of food that is safe for consumption (food safety attributes), high nutritional content (nutritional attributes), and environmentally friendly (ecolabelling attributes), and can increase farmers' income and foreign exchange [1].

In Central Sulawesi Province, mainly in the Palu Valley, there are local superior shallot commodities that are well known. This onion is one of the horticultural vegetable commodities which is commonly used as a seasoning flavouring, raw material for the food industry. Currently, many local types of shallots are cultivated in the Palu Valley, but the product produced is still low [2]. The potential source of organic matter is weeds, which are varied and abundant in Indonesia [1]. Utilization of weeds as compost material has a double advantage. First, the use of weeds can reduce losses due to crop competition with weeds, and secondly, at the same time transforming weeds which previously harmful into something useful.

Every area has a variety, and different types of weeds, the differences in each weed are caused by natural factors and human actions [3]. One of the actions that cause a weed to evolve is the act of over-spraying herbicides [4-7]. This action can cause chemical content that plant growth regulator (PGR) and nutrients in weed changing. Apart from processing weed plants evolve, the action of spraying also makes the quality of a soil decrease. Excessive use of pesticides with the same type can cause weeds to become resistant. Weed resistance to the use of pesticides can cause changes in the chemical content, namely PGR and the nutrients in the weeds. In addition to making weeds evolve, the action of spraying also makes the quality of a soil decrease. The distribution of weeds from one area to another differs according to the factors that influence it. Weed identification and identification of dominant weed types is the first step in determining the success of weed control [8].

This research aimed to understand the diversity, species, and plant growth regulator and nutrient content of local weed in Tawaeli Sub-District, Palu City.

Weeds can be defined as plants whose benefits still not yet known, usually, these plants will associate and develop around the main cultivated crop. Weeds may interfere with the growth of cultivated plants so that weeds are considered to be detrimental to farmers [10, 11]. Weeds that grow around cultivated plants will compete in absorbing nutrients needed for cultivated plants, so the presence of weeds is not expected. However, several studies have been carried out to find out the benefit of the weed community. Weeds that grow in unwanted places and whose benefits are not yet known, including as ingredients for making traditional herbal medicine [12]. A source of organic ameliorant material and as a source of organic material containing nutrients for plant growth. Several areas in Java Island have used weeds directly to be various kinds of economically valuable handicrafts [13].

There are many plant species categorized as weeds at this study site. The identification results of weed species on cultivated land in Tawaeli Sub-District, Palu City, found 27 species of weed species from 17 different families. A previous study showed that approximately 350 of weed species from 150 genera and 60 families were reported as rice weeds, of which, Poaceae spp, more than 80 species, and Cyperaceae spp. more than 50 species [14].

On agricultural land in the study location, a total of 1301 species were found that generally fall into the medium diversity (H ') category. The most dominant species was Coccinia SP. from the Cucurbitaceae family (H '= 1,10), and the least was Amorphophallus SP. from the Araceae family (H '= 0.68). In other agricultural areas in rice fields of Karya Mukti Village, Dampelas Sub-District, Donggala Regency, Mazidaturohmah et al. (2018) reported 14 types of weed plants with a total of 1,385 individuals consisting of 7 identified families in the agricultural area. The most dominant type was Monochoria vaginalis (Burm.F.) C. Persal, with an IVI value of 43.04%, while the species with the lowest IVI value was Eclipta alba (L.) Hassk with an IVI of 1.75%. The index diversity of species in the study was classified as moderate, about 2.14 [14]. Weed diversity is influenced by environmental factors as shown in Table 3, namely temperature, air pressure, humidity, length of daylight, rainfall, wind speed [15]. The diversity and large number of individuals in Central Sulawesi demonstrate the importance of weed management [16].

Weeds are organic materials known to have many bio-components and nutrients. The results of the nutrient evaluation show that the weed species in our observation area contained several nutrients that can be used to improve soil fertility, including Nitrogen (N), Phosphorous (P), Potassium (K), Calcium (Ca).), Magnesium (Mg), Iron (Fe), Cuprum (Cu), Zinc (Zn), Manganese (Mn), Boron (B), and Sulfur (S). Species "Unidentified" contained the highest P element at 0.16%. Tabernaemntana divaricata (L) R. Br. Ex Roem. g Schult was known to have the highest N, K, and S elements compared to other species, was 1, 85%, 1.00%, and 0.25%, respectively. Sida acuta Burm. F. contained the highest element B, which was 28.71 ppm. Then, weed species Lantana cemara L. has the highest elements of Fe, Cu, Zn, and Mn, was 1615.52 ppm, 51.22 ppm, 51.12 ppm, and 104.94 ppm, respectively. While Ciperus SP. contained the highest Ca element, about 2.78%.

Currently, the development of growth-supporting fertilizers has been deep by utilizing organic waste materials and other unmanaged natural materials. Akanbi and Togun [17] studied that the high content of natural nutrients in corn waste compost combined with urea fertilizer was able to increase the growth of Amaranthus cruentus L. Also, Zhang et al. [18] found the potential for using organic fertilizers to support the growth of ginger rhizome. These organic fertilizers can supply nutrients as well as suppress the development of microbes Fusarium oxysporum f. sp. zingiberi (Foz), which destroys the rhizome.

Organic fertilizers are known able to increased soil fertility and are environmentally friendly compared to inorganic fertilizers [19-22]. The use of fertilizers from natural materials such as compost can be an alternative in improving crop cultivation production, also reducing the costs [23, 24]. Utilization of waste and unmanaged natural materials such as weeds is one way out for farmers. The growth-supporting nutrients contained in weeds is very beneficial for the growth of cultivated plants. Several studies on weeds also show the inline results with this study. A study conducted by Nugroho et al. (2019) [1] on the compost of Siamese weed (Chromolaena odorata l.) grows in the agricultural area of the Special Region of Yogyakarta, proven that this weed contains nutrients of N, P, and K valued 2.56%, 0.38%, and 2.41 %, respectively, and was able to stimulate an increase in the leaves number on shallots compared to an-organic fertilizer. Meanwhile, rice weeds grow in coastal areas, Sungai Berut Sub-District, Bengkulu contains calcium 0.02 - 0.13%, protein 5.28 - 7.39%, and phosphorus 0.16 - 0.33% [25].

The diversity and total of individuals are quite large in Central Sulawesi, demonstrating the importance of weed management. Weed management can increase the value of benefits and reduce the level of losses due to weed growth around cultivated plants. Utilization of weeds may clear the agricultural land from competing for crops that can take up important soil nutrients for cultivated crops. Also, the potential for the use of plants that disturb these cultivated plants is a good value of nutrients. The minerals contained can be used as a source of nutrients for cultivated plants. So, it can help in increasing agricultural output.