Practicum Learning Techniques in Brassica chinensis Pesticide Contamination Test on UISU FKIP Biology Students 2018-2019

Brassica chinensis contains nutrients that are complete enough so that when consumed it is very good for maintaining a healthy body. The content contained in Brasca chinensis is calories, protein, fat, carbohydrates, fiber, Ca, P, Fe, Vitamin A, Vitamin B, and Vitamin C. According to BPS (2018) consumption of mustard has increased from year to year, and in in 2016 mustard production reached 193.7 tons, this figure is very high when compared with other vegetables such as spinach, tomatoes, and kale. There are many markets in the city of Medan that sell Brassica chinensis. Brassica chinensis in the Medan city markets are mostly taken from the wholesale market in Simpang Selayang, Medan Tuntung District, and the wholesale market is also a mustard distributor from Berastagi.


INTRODUCTION
Brassica chinensis contains nutrients that are complete enough so that when consumed it is very good for maintaining a healthy body. The content contained in Brasca chinensis is calories, protein, fat, carbohydrates, fiber, Ca, P, Fe, Vitamin A, Vitamin B, and Vitamin C. According to BPS (2018) consumption of mustard has increased from year to year, and in in 2016 mustard production reached 193.7 tons, this figure is very high when compared with other vegetables such as spinach, tomatoes, and kale. There are many markets in the city of Medan that sell Brassica chinensis. Brassica chinensis in the Medan city markets are mostly taken from the wholesale market in Simpang Selayang, Medan Tuntung District, and the wholesale market is also a mustard distributor from Berastagi.
As we know that every crop on agricultural land, especi-ally in Berastagi, is generally sprayed with pesticides because the role of pesticides in increasing agricultural production is undeniable. One of the plants that is often sprayed with pesticides is a vegetable plant, especially the Brassica chinensis plant. This happens because the shape and structure of the Brassica chinensis plant allows caterpillars to nest between their leaves and also because Brassica chinensis has many natural enemies from insects. The effect of the correct use of pesticides will be very quickly seen in a decrease in pest populations and plant diseases. The benefits of pesticides that are felt very quickly make farmers hang too high hopes on pesticides. As a result, farmers make pesticides the only mainstay in controlling pests and plant diseases. Due to limited knowledge, the use of pesticides is often mistaken. For example, increasing doses and concentrations beyond the rules, mixing various types of pesticides, ignoring work safety rules, and so on. Pesticides sprayed on plants will certainly leave a residue. Pesticide residues are found in all parts of the plant such as stems, leaves, fruits and roots. Even though they have been washed or cooked, these pesticide residues are still found in food. Pesticide residues are active in the human body so they will have a negative impact on human health that consumes vegetables that contain pesticide residues continuously. Syakir (2011) explained that healthy and environmentally friendly agricultural products are already a guideline of the global market (AFTA, APEC, and WTO), with eco-labeling attributes, nutritional attributes, and safe consumption (food safety attributes).
Many people assume that to get good quality food such as vegetables, can be obtained by buying in modern shopping places such as hyper markets. This is because the majority of human consumption materials such as food sold on the hyper market are imported from outside the region and even from abroad which are believed to have better quality than the local market. In fact, if examined deeper, not all food ingredients of local production are of low quality. Food imported from outside the region also does not guarantee 100% better quality than local production. The process of propagation in the laboratory through testing trials for students is needed in producing fresh and high quality mustard greens. Tests conducted by students on laboratory techniques in the laboratory turned out to give satisfactory results.

Research Location
The location of the study was conducted in Biology Laboratory FKIP UISU. Start from March 2019 until May 2019.

Population and Sample
The population in this study were all mustard greens (Brassica chinensis) which were sold in Simpang Limun market, Halat market, Sambas market, and Suka Ramai market in Medan. The sample in this study was mustard greens using purposive sampling technique that is as many as 5 samples with the criteria of mustard greens (Brassica chinensis) which are more traded and vegetables that look perfect in terms of physical namely leaves without holes.

Research Design
This study uses Semester level II as a research subject, and pretest treatment as a variable factor T1 and treatment as a variable Y, then posttest as a variable T2.

Work Procedure
Crossidolomia binotalis larvae obtained from post-harvest Brassica chinensis vegetable gardens are kept in plastic jars and fed with Brassica chinensis leaves, at the top of the jars covered with gauze. The pupae that is formed remains maintained in a jar until it becomes an imago. During the imago phase, Crossidolomia binotalis is fed honey placed on cotton that has been mixed with a little aquades. Then the eggs produced from the same time are kept until they reach Instar I.

Application
1. Prepare pieces of Brassica chinensis leaves for larva food of a certain size.
2. Place the pieces of Brassica chinensis leaves in a petri dish. To prevent the dryness of the leaves, the petri dish was previously coated with moistened filter paper.
3. The instar I larvae of Crossidolomia binotalis, which are of the same size and age, are infested on Brassica chinensis leaves, after the larvae are fasted for 2-4 hours.
4. For control, Brassica chinensis leaves are dipped in distilled water for 5 minutes, then air dried until the leaves are no longer wet.

Death of the Larva
Observation of larval death of Crossidolomia binotalis was carried out 6, 12, 24, 48, 72 hours after application (starting at 08.00, 14.00, 20.00, 02.00, etc. until reaching 72 hours). Larvae are said to die if the larvae when touched with the tip of the brush are no longer moving or stationary. The percentage of larval mortality is calculated using the Dj formula. Prijono namely: where: I = Percentage of larval death a = Number of dead larvae b = total larvae

Larva weight
The average weight of the first instar larvae before application, namely by weighing ten instar larvae to one other than the larvae for treatment, and the average weight of larvae after completion of the study, calculated the weight of the larvae still alive from each treatment (including control).

Area of Damage
Calculate the area of damage to mustard greens eaten by crossidolomia binotalis larvae using millimeter paper.

Pre -Test
Pre test is a test conducted at the beginning of learning of the material taught before the teaching and learning process takes place which aims to determine the basic abilities of students to additives substances and contaminants in food with a total of 5 questions (items) and questions in the form of essays.

Post -Test
Post test is a test conducted at the end of learning about the material that has been studied which aims to determine student learning outcomes after studying material additives and contaminants in food. The test in this study is in the form of essays with a total of 10 questions (items). This can be seen through the Post Test table (Blue print)

RESULTS AND DISCUSSION
The following are the results of observations of the treatment test: table 1.The larvae died an average of 6 hours after the test of the presence or absence of pesticide contamination on the leaves of Brassica chinensis.
Data and results of larval mortality 6 hours after the treatment test can be seen in the above table. The average results show that the lowest larval mortality rate is that of Brassica chinensis samples taken from control, inversely proportional to Brassica chinensis samples taken from Halat market which shows the highest mortality rate of larvae. Brassica chinensis samples taken from Suka Ramai market showed the second highest larval mortality after samples taken from the Halat market, and followed by Brassica chinensis samples taken from the Simpang Limun market, then Brassica chinensis samples taken from the Sambas market.

RESULT OBSERVATION
In from the graph it can be seen that in repetition III where Brassica species taken from the Halat market show the highest lift of 4, and the highest number of deaths in larvae which also have a direct impact on the average number of larval deaths.
Data and the average yield of larvae death 12 hours after the treatment test can be seen in the table below. The average results showed that the lowest larval mortality rates were Brassica chinensis samples taken from control, while Brassica chinensis samples taken from the Suka Ramai market and Halat market showed the highest larval mortality rates, followed by Brassica chinensis samples taken from the Simpang Limun market, then Brassica chinensis samples taken from the Sambas market. Data and results of larval mortality 24 hours after the treatment test can be seen in the table below. The average results showed that the lowest larval mortality rates were Brassica chinensis samples taken from control, while the highest larval mortality rates came from Brassica chinensis samples taken from Halat and Suka Ramai markets, followed by Brassica chinensis samples taken from the market. Simpang Limun, then Brassica chinensis samples taken from the Sambas market. Data and the average yield of larvae 48 hours after the treatment test can be seen in the table below. The average results show that the lowest larval mortality rate is Brassica chinensis samples taken from control, while the highest larval mortality rate comes from Brassica samples chinensis taken from Suka Ramai market, followed by Brassica chinensis samples taken from Halat market, then Brassica chinensis samples taken from Simpang Limun market, and Brassica chinensis taken from Sambas market. Data and the average yield of larvae death 72 hours after the treatment test can be seen in the table below. The average results showed that the lowest larval mortality rate was Brassica chinensis samples taken from control, while the highest larval mortality rates came from Brassica chinensis samples taken from the Suka Ramai market, followed by Brassica chinensis samples taken from Halat market, then Brassica chinensis samples taken from the Simpang Limun market, and Brassica chinensis samples taken from the Sambas market.

CONCLUSION
Based on the results of the study it can be concluded that: 1. There are pesticide contents in several markets in the city of Medan with an indicator of mortality from larval Crossidolomia binotalis.
2. The highest mortality of Crossidolomia binotalis larvae occurred in Brassica chinensis samples taken from the Suka Ramai market with an average of 6.22% after 72 hours of application, then followed by Brassica chinensis samples taken from Halat market, Simpang Limun market, market Sambas, respectively of 5.33%, 2.22% and 1.78%.
3. The higher the content of pesticides in the leaves, the higher the mortality rate of larvae, the lower the weight gain of larvae, and the less extensive damage that occurs on the leaves of Brassica chinensis because it is not eaten by Crossidolomia binotalis larvae.