The aim of the study is to determine students’ learning difficulties at all Public Senior High School (SMA) in Medan. This research is descriptive. The population of the study is all students of class XII totaling 7272 in 21 Public Senior High Schools (SMA Negeri) spread over 15 districts. Samples were taken using Purposive Sampling, they are 524 students of class XII in 7 schools. The techniques for data collection use questionnaires of students’ learning difficulties and interviews. The finding of the study concluded that factors caused the biggest students’ learning difficulties derived from external factors (44%), which consist of laboratories factor (49%), books (45%) and the teacher factor (37%). The percentage of internal factors was (43%), which consist of the talent factor (50%), interest (44%) and motivational factors (36%).

This research was conducted to find out the effect of ab mix nutrient on growth and yield of Pak choi (Brassica chinensis L.) plants under hydroponic wick system condition. The research design used was non factorial Complete Randomized Design (CRD) with 5 levels of ab mix nutrient concentrations (0, 650, 1300, 1950, 2600 ppm), with 3 replications in each treatment. Each repetition consists of 6 plants, making a total 90 experimental units. The parameters observed were plant’s height, number of leaves, leaves area, fresh and dry weight, harvest index, leaf chlorophyll content, and root volume. Data was analyzed by using one way ANOVA, and DMRT as follow up. Research result shows that in hydroponic wick system ab mix nutrient gave very significant effect on pak choi (Brassica chinensis L.) parameters, such as: 1) plant’s height, 2) number of leaves, 3) leaves area, 4) dry weight 5) harvest index, and significantly effect on 6) fresh weight. However, it did not gave significant effect on root volume. The best results for each parameters observed were: number of leaves was 18.78, leaves area was 47.32 cm2, fresh weight was 33.57 gr, dry weight was 2.40 gr and harvest index was 99.15%, all were obtained from ab mix 1950 ppm treatment. The best results for plant height parameter was 8.71 cm obtained from ab mix 2600 ppm treatment.

Physical and sensory quality of Java Arabica green coffee beans W B Sunarharum, S S Yuwono, N B S W Pangestu et al. Abstract. Drying agricultural product is a post-harvest process that consumes significant energy. It can affect the quality of the product. This paper deals with literature review and field survey of drying methods of coffee beans of Indonesia farmers. The objective is to supply the necessary information on developing continuous solar drier. The results show that intermittent characteristic of sun drying results in a better quality of coffee beans in comparison with constant convective drying. In order to use energy efficiently, the drying process should be divided into several stages. In the first stage when the moist content is high, higher drying air temperature is more effective. After this step, where the moist content is low, lower drying air temperature is better. The field survey of drying coffee beans in Sumatera Utara province reveals that the used drying process is very traditional. It can be divided into two modes and depend on the coffee beans type. The Arabica coffee is firstly fermented and dried to moisture content of 80% using sun drying method, then followed by Green House model of drying up to moisture content about 12%. The latter typically spends 3 days of drying time. On the other hand, The Robusta coffee is dried by exposing to the sun directly without any treatment. After the coffee beans dried follow by peeled process. These findings can be considered to develop a continuous solar drying that suitable for coffee beans drying.

Nepenthes sp. is a carnivorous plant with unique shape and color shades. This unique plant has a special leaf modification called a pitcher which has the capability in catching insects and small animals. The purpose of this research was to know the types and habitat of Nepenthes sp. that found in six regencies in North Sumatra. The pitcher plants inventoried from South Tapanuli, Central Tapanuli, Humbanghasundutan, Toba Samosir, Dairi and Samosir regency in North Sumatra. The research type and method were conducted by descriptive qualitative and survey method research. The morphology data of Nepenthes sp. used to identify the types of Nepenthes sp. in North Sumatra. Inventory result of Nepenthes sp. from six regency showed that there were five original species in North Sumatra namely Nepenthes tobaica, Nepenthes gracilis, Nepenthes ampullaria, Nepenthes eustachya, Nepenthes rhombicaulis and one natural hybrid species Nepenthes reinwardtiana x spectabilis. Nepenthes tobaica, Nepenthes gracilis had upper and lower pitchers while Nepenthes ampullaria, Nepenthes eustachya, Nepenthes rhombicaulis and Nepenthes reinwardtiana x spectabilis just had an upper or lower pitcher. All species lived in low or high lands and most of them found in peat area, high humidity, and high light intensity.

This research aims to determine the effect of gamma-ray irradiation on the phenotypic of the garlic cultivar Doulu. The study was conducted in April-August 2018. Radiation on the bulb garlic is carried out at the centre of Safety and Meteorological Technology (PTKMR), BATAN, Jalan Lebak bulus Raya No. 49 Jakarta. Bulb planting is done at the research Hall of vegetable crops, Tongkoh village, Berastagi, North Sumatera. The draft used in this study is non factorial group random draft with 6 radiation dose treatment of 0 Gy (Control), 2 Gy, 4 Gy, 6 Gy, 8 Gy and 10 Gy. Each of the treatment levels is repeated as much as 4 and consists of 10 cloves of garlic. The observed quantitative data parameters are growing age, crop height, number of leaves, number of cloves, heavy bulbs, diameter of bulb, heavy cloves and diameter of cloves. The qualitative data parameters observed are bulb structures and bulb forms. Qualitative Data obtained is analyzed using various prints with advanced test of the smallest real difference (LSD). The results shows the irradiation of the influential gamma rays in the height of the plant, the number of leaves, the number of cloves, the weight of bulbs, the diameter of the bulb, the weight of cloves, and the diameter of garlic cultivars Gamma-ray irradiation produces a variety of bulb structures and bulb shapes. The parameters observed were structure and shape bulb based on IPGRI. Results showed that there were differences in the structure and shape of garlic bulbs.The structure of bulb are regular two-fan groups, regular multi-cloved radial, regular quadruple, regular two-cloved, and Irregular. The shape of bulb are Flat, Flat globe, Rhomboid, Broad oval, Globe and Ovate.