Nitrogenase Activity and Plant Physiological Process of Soy Bean Under Saturated Soil Culture on Mineral and Peaty Mineral Soil

Abstract

Development of soybean (Glycine max L.) production in sub-optimal land like tidal land is still less performed. Soybean productivity on tidal land is still low due to the application of conventional farming technologies, so it is not able to mitigate the negative effects of high levels of pyrite, Al, Fe, and Mn and the low availability of P and K. The possible cultivation technique is saturated soil culture (SSC) that able to influence the conditions below the root zone, physiological activity, adaptability and acclimatization of soybeans. The research objective was to study the physiological characteristics and growth of soybean under water-saturated conditions in minerals and peaty mineral soils on tidal land. The experiment was carried out in plastic house, experimental station of Cikabayan, Bogor Agricultural University from December 2014 until March 2015. A three factorial completely randomized design was used in this experiment. The first factor was cultivation technique, consisted of dry and saturated soil culture. The second factor was varieties (Willis and Tanggamus) and the third factor wassoil type (mineral and peaty mineral soil). The result showed that saturated soil culture increases the number of stomata per plant, chlorophyll (a and b), root volume, number of root nodules, roots ethylene content, plant biomassdry weight and grain per plant, and number of filled pods. Interaction of saturated soil culturetechnique and mineral soil produce the highest number of stomata per plant, number of nodules, plant biomassdry weight and number of filled pods. Interaction between saturated soil cultureand Tanggamus resulted on the highest number of nodules and filled pods. Dry cultivation increase the density of stomata, but the plant growth at soil moisture below field capacity (up to 40% field capacity), continually lowering the growth and production of soybean. Tanggamus has higher number of stomata per plant, total chlorophyll, root volume, plant biomassweight and number of filled pods, while Willis has higher density of stomata, the rate of roots ethylene formation, number of nodules and dry weight of grain per plant. Ethylene formation in the root zone supports the formation of new roots and subsequently increase plant nutrient uptake, thus increasing the dry weight of grains per plant.