Efisiensi Penggunaan Cahaya Matahari oleh Tanaman Tebu Pada Berbagai Tingkat Pemupukan Nitrogen dan Fosfor

Abstract

Efisiensi penggunaan cahaya merupakan komponen krusial pada pertumbuhan dan perkembangan tanaman yang dihubungkan dengan produksi akumulasi biomassa dari intersepsi energi. Produksi tanaman ditentukan oleh partisi dan akumulasi biomassa tanaman. Proses tersebut tergantung pada peran kanopi (tajuk) dalam intersepsi PAR (Photosynthetically Active Radiation) yang disebabkan oleh Indeks Luas Daun (ILD) dan struktur kanopi serta proses konversi radiasi menjadi akumulasi biomassa tanaman. Defisiensi N dan P menurunkan Indeks Luas Daun (ILD), kandungan spesifik N dan P pada daun (SLN dan SLP) tanaman sehingga terjadi proses reduksi intersepsi dan efisiensi penggunaan cahaya oleh struktur tajuk tanaman.

Light use efficiency is a crucial parameter in plant growth associated with accumulation of energy interception. Nitrogen and phosphorus deficiency can affect leaf area index (LAI) and specific leaf nitrogen and phosphorus (SLN and SLP) content resulting in reduction efficiency of light intercepted by plant canopy structure. This research was conducted in Kebun Bunga Mayang PTPN VII, North Lampung Regency, Lampung Province. Field observation is located on latitude of 04050’S and longitude of 104052’ E with elevation 38 meter from sea level which conducted from July 2008 to September 2009. Sugarcane was planted on August 20th 2008 and harvested on September 8th – 10th 2009. Treatments were distributed in the field under a randomized block design factorial with three replications. An increasing amount of nitrogen fertilizer (N) improved sunlight use efficiency by sugarcane crops. Fertilizing with 225 kg N ha-1 (489 kg Urea ha-1) on maximum stem phase (5 – 9 MAP) produced value sunlight use efficiency at 2.29 g MJ-1. An increasing efficiency value was linearly affected stem dry matter which is the major component in sugarcane production. On the contrary, the increasing of phosphor (P) fertilizer did not improve value sunlight use efficiency but affected stem dry matter on maximum seedling phase (3 MAP), maximum stem phase (9 MAP) and harvest phase (11 MAP) ; total dry matter on steady seedling phase (5 MAP) and maximum stem phase (9 MAP). Interaction between N and P were not increase value sunlight use efficiency by sugarcane crops. Thus only significantly affected dry matter of stem production on emergence phase (1 MAP) and steady seedling phase (5 MAP) ; total dry matter on emergence phase (1 MAP). A further research is still needed to conduct in order to investigate the amount of N doses level regarding on the improving value sunlight used efficiency due to its increasing level of N.