Giant Reed Screening to Salinity Levels

In the frame of OPTIMA project (Optimization of perennial grasses for biomass production, n. 289642) 40 ecotypes of giant reed have been compared with the aim to deliver information on contrasting clones of giant reed tolerant and sensitive to salinity. In a split-plot experimental design with three replications, three NaCl levels (S0, S1 and S2) were applied to 40 giant reed ecotypes. During the growing cycle it has been measured: (i) soil electrical conductivity (EC), at transplanting time and then after 36, 45, 75 and 115 days after transplant (DAT); (ii) physiological measurements: net photosynthesis and SPAD on 63, 80 and 115 DAT. At harvest, aboveground and belowground biomass has been also measured. Soil salinity concentration in the average of the 40 clones per treatment increased during the growing cycle. In all treatments EC started at less than 1 dS m-1 to reach 2.2 dS m-1 in the S0, 6.3 dS cm-1 in the S1 and 9.1 dS cm-1 in the S2 treatment after 115 DAT. Soil EC also increased in the S0 treatment for the effect of salt concentration in the tap water. Net photosynthesis and SPAD unit decreased during the measurement time which is ascribable to the effect of environmental variables. Highest level of net photosynthesis and SPAD unit were recorded in S0 than S1 and S2. The same trend was observed for aboveground dry biomass, main stem height and number of stems at harvest. Specific leaf area (SLA), leaf area index (LAI) and leaf water content were slightly higher in S0 than S1 which in turn were higher than S2, however leaf to stem ratio and specific leaf weight were higher in S2 than S1 and S0. The highest rhizome and roots dry weights were obtained with S1, which were slightly higher than S0 and S2. A preliminary screening (coefficient of variability (CV) x aboveground biomass yield) showed that some clones resulted tolerant while other sensitive to salinity level.