Autecology of pepper plant (Piper nigrum L.) in Lampung Province: environmental characteristic and its factors affecting the productivity of pepper plant

Abstract

Understanding the characteristic of crop plant species is a pivotal step to achieve the cultivation success on agricultural practices. Each plant requires a specific environmental condition for its growth and maturation. In case of pepper plant, environmental factors such as altitude and rainfall considerably affect on the growth as well as productivity of this plant. As one of pepper production center in Indonesia, Lampung Province has diversity of pepper varieties and different environmental characteristic with gradient of altitude and precipitation. Based on Dinas Perkebunan (Plantation Office) of Lampung Province, productivity of pepper in Lampung tends to decrease recently. The average pepper production was 651 kg/ha in 2005, 478 kg/ha in 2007 and 461 kg/ha in 2011. Those, well-knowledge about autecology of pepper plant in Lampung Province become an important concern to solve the problems on pepper cultivation. The main objective of this research was to study the autecology of pepper plant in Lampung Province. The research covered specific objectives were (i) to obtain the information about phenology of pepper plant in Lampung Province, (ii) to determine the recent environmental condition of pepper plant habitat including biotic and abiotic factors, and (iii) to investigate the environmental factors that affect the productivity of pepper plant in Lampung Province. Study about phenology of pepper plant in Lampung was conducted through direct observation on selected plot in two areas i.e. (i) Kebun Percobaan Balittri, Cahaya Negeri Village, Subdistrict of Abung Barat, North Lampung and (ii) Kebun Percobaan BPTP, Negara Ratu Village, Subdistrict of Natar, South Lampung. Whereas, study about of environmental characteristics and its factors effect on the productivity of pepper plant was conducted in four districts with different altitude i.e. (i) Sekincau Subdistrict, West Lampung, (ii) Abung Barat Subdistrict, North Lampung, (iii) Margatiga Subdistrict, East Lampung, and (iv) Natar Subdistrict, South Lampung. Observation and measurement were conducted to obtain the data for environmental factors, variability and productivity of pepper plant. Analysis of soil chemistry was performed to determine the condition of soil fertility on each location. To study the biotic component, insects were explored as study case to investigate the relationship between insect and pepper plant. Then, statistical analyses were performed to study the relationship between environmental factors including abiotic and biotic factors and the productivity of pepper in Lampung Province. The result showed that the phenology of pepper plant in Lampung is started from the seed or cutting, seedling, immature, and adult. In the mature period, pepper plant having an annual cycle between vegetative and generative phase. Vegetative phase is started around September to December, while generative phase is from January to August. Flowering characteristic of pepper plant varieties i.e. Natar 1 and Natar 2 have seasonal flowering time which is early flowering time follow the rainy season in the local region. In Abung Barat, variety of Natar 1 has higher variability and productivity than Natar 2. In contrast, variability and productivity of Natar 2 was higher than Natar 1 in Natar Subdistrict. The difference of environmental condition might affect the productivity of pepper plant in Lampung Province. Environmental characteristic of pepper plant habitat in four locations related to climate condition (average per year) i.e. (i) Sekincau has rainfall 1836 mm/year, temperature 21°C, humidity 93.6%, micro-temperature 26 °C during the day and 17 °C at night, micro-humidity 92.91%, micro-light intensity 911.8 lx, and moderate of soil fertility; (ii) Abung Barat has rainfall 2160 mm/year, temperature 27.23°C, humidity 83.03%, micro-temperature 31.4 °C during the day and 23.56 °C at night, micro-humidity 79.41%, micro-light intensity 972 lx and low/poor of soil fertility; (iii) Margatiga has rainfall 2169 mm/year, temperature 27.6 °C, humidity 79.8%, micro-temperature 31.4 °C during the day and 23.74 °C at night, micro-humidity 78.41%, micro-light intensity 990 lx, and poor of soil fertility; (iv) Natar has rainfall 1225 mm/year, temperature 27.31 °C, humidity 81.5%, micro-temperature 32.26 °C during the day and 23.28 °C at night, micro-humidity 82.74%, micro-light intensity 923 lx, and poor of soil fertility. Based on the criteria of land suitability for pepper plant, Sekincau and Natar are less suitable for pepper cultivation in related to humidity and rainfall respectively, whereas Abung Barat and Margatiga is classified as suitable for pepper cultivation especially for temperature and precipitation. In the aspect of biotic environmental factor, 12 insect orders were found on the soil surface of pepper plant from four locations. The most dominance insect is Order Hymenoptera especially Family Formicidae which was found abundant in the pepper habitat. The analysis showed that those insects did not directly associate with the pepper plant. Their occurrence was influenced by environmental conditions such as altitude, rainfall, and human activities. Several location or pepper field were located close to housing area and caused the domination of certain species such as tramp ants that co-exist with humans. Environmental factors that considerably effect on the productivity of Natar 1 variety were rainfall, humidity, light intensity, pH of soil and temperature. For the variety of Natar 2, the productivity was affected by humidity, precipitation, light intensity, C/N ratio and soil pH. Based on PCA on each location, the productivity of pepper in Sekincau positively correlated with light intensity and temperature. In Abung Barat and Margatiga positively correlated with temperature and CEC of soil. Whereas in Natar positively correlated with CEC and C/N ratio of soil. The most suitable environmental habitat for pepper plant in Lampung Province are in Margatiga and Abung Barat.