PENGARUH APLIKASI BAKTERI FOTOSINTETIK Synechococcus sp. TERHADAP LAJU FOTOSINTESIS TANAMAN KEDELAI

Abstract

Soybean needs increased yearly along with the increasing population. The national product has not meet the domestic needs, so that the rest was fulfilled by import. Soybean plants classified in the leguminoseae family which is a C plant. As a C plant, soybean has low photosynthetic efficiency particularly when it is exposed to high radiation and air temperature. This efficiency could be improved using biotechnology of forming association between soybean and Synechococcus sp. bacteria, a photosynthetic bacteria. Previous studies proved that the presence of bacteria Synechococcus sp. on leaf surfaces improved plant photosynthetic attributes, such as mesophyll thickness, cholorophyll content, and stomatal conductance. Growth of soybean plants is divided into two major phases, vegetative and generative phases. Each phase of growth has unique physiological stage of plant development and each stage has different characters. Therefore, the effect of Synechococcus sp. bacteria innoculation should different on each critical growth stage of soybean. 3 The objective of this research was to study the effect of Synechococcus sp. bacteria innoculation on the rate of photosynthesis of soybean. To address this objective, the research was conducted based on randomized complete design with 5 levels of treatments, namely control that is plant without Synechococcus sp bacteria innoculation (P0), Synechococcus sp. bacteria innoculated once at flower inisiation stage (P1), Synechococcus sp bacteria innoculated twice, ie at vegetatife exponential growth and flower inisiation stages (P2), Synechococcus sp. bacteria innoculated three times, ie at flower inisiation and pod formation stages (P3), Synechococcus sp. bacteria innoculated twice, ie at vegetatife exponential growth, flower inisiation and pod formation stages (P4). Each treatment was replicated ten times. Observation as focused on photosynthetic rate (Fv/Fm), the number of leaves per plant, leaf chlorophyll content (µmol/m 8

2 ), stomatal conductance (mmol H 2 O/m 2 /s), leaf area index, plant height (cm), the number of branches, weight of 100 seeds (g), seed weight per plant (g), the number of seeds per plant. Collected data then was analyzed with the value of SEM (Standard Error of the Mean). The results showed that innoculation of Synechococcus sp. bacteria at flower inisiation stage increases the photosynthetic rate of soybean by 17.52%, that leads to increase soybean seed production by 40.68%.