Biomass Accumulation and Doubling Time of Some Duckweeds Native To Iran: Biotechnological Application

Background and aim: duckweed (lemnoideae subfamily) in iran is consisting of at least three recognized genus with 6 species which have been distributed in wetlands. duckweeds are the most simplest and smallest flowering monocot plants with free floating aquatic fronds, which can propagated asexually every 2-3 days. duckweeds could be a main source of balanced amino acids and useful carbohydrate like starch which is becoming increasingly promising for biotechnological application. due to the most rapidly growing rate of duckweeds, measuring the biomass accumulation and doubling time are important factors for determining the growth potential especially for native species. relative growth rates (rgr), doubling times (dt) and relative weekly yields (ry) of thirty three distinct duckweed clones (collected from north of iran) belongs to two genus were determined under standard cultivation condition. statistical analysis were done using sas software. the rgr ranging from 0.043 to 0.440 day-1, dt from 2 to 9 days and ry from 7 to 60 mg.week-1, which are comparable with previous studies. these data support that these domestic duckweeds have high productivity value and therefore could be a rich source of protein for alternative human food, livestock feeds and recombinant protein production.methods: all plant materials consisting two genus lemna and spirodela were surface sterilized and pre-cultivated in axenic conditions at 25 °c. all the culture were propagated in 50 ml sterile nutrient medium and under 16h' light and 8h' dark. growth rates parameters were calculated within 7 days using fronds number, fronds fresh weight and dry weight as described by naumann and coworkers (2007). means value of rgr, dt and rt were compared with one-way anova using the student– t test at the level of p = 0.05. dt means how much time is required to double the number of fronds by calculating the frond numbers or fronds fresh or dry weight. ry means how many fronds or how much fresh or dry weight is produced after 7 days starting from first inoculum of fronds.results: the rgr, dt and ry value for 26 ecotypes of lemna are ranging from 0.043 to 0.430 day-1, 2.9 to 9 day-1 and 7.2 to 37 mg. week-1 respectively. the rgr, dt and ry value for 6 ecotypes of spirodela are ranging from 0.093 to 0.467 day-1, 1.47 to 6.16 day-1 and 16.36 to 60 mg. week-1 respectively. the value was reported based on fresh weight of fronds in the beginning and after 7 day. based on these data the decrease in the rgr value causes the time needed for doubling the biomass (dt) decreased and relative yields (rt) per week were increased. the differences of mean value of the parameters were statistically significant among these ecotypes.conclusion: the rgr and dt and ry data showed the significant potential of various iranian native duckweeds (ecotype) as an appropriate platform for biotechnological applications. this research was partially supported by grants from insf (no. 97024978) and nigeb (no. 980301-ii-714)