To verify the productivity model in optimum conditions which relates the aerial biomass to the quantity of intercepted PAR; To use such a model to determine the potentiality of a sweet sorghum crop for biomass and ethanol production. To analyze the effects of N deficiency on actual production; To test different genotypes for their aptitudes to produce total biomass, ligno-cellulose or sucrose.
The project is a part of a larger EC-project to investigate the productivity potential of sweet sorghum as sugar, ethanol and fibre plant at different European climatic conditions. The Research project includes following parameters :
1) Genotype evaluation: At the same site several genotypes of sweet sorghum are under evaluation in non limiting growth conditions (well irrigated and sufficient fertilizer supply). Each genotype will be harvested around the expected optimum date. The total biomass and sucrose content will be determined at each harvest and composed to the data obtained from the common genotype to be grown at different European sites.
2) Nitrogen treatments: Three levels of nitrogen supply are considered, N1 N2, and N3. The higher level (N3) is to be non limiting. The N3 level would be split in several applications to ensure the N nutrition to be non limiting during the growth period. The quantities of N applied will be discussed in each case according to the potentiality of N soil mineralisation in each situation.
3) Biological measurements : Each week after seed emergence a subplot of 3mX2m will be cut at soil level and removed for determination of green biomass and dry matter content (on sub samples). From these data, Aerial Dry Matter will be calculated. on sub samples obtained from individual plants removed from each plot. Other parameters will be determined:
- proportion of leaf, stem and dead material
- leaf specific weight by measurement of area (by optical planimeter) and dry weight of laminas in order to calculate the Leaf Area Index
- nitrogen content of total plant and (if possible) of each fraction (leaves and stems).
4) Physical measurements:
- meteorological data measured on the site of experiment: air temperature incident radiation, rainfall, Penman PET
- soil parameters: temperature (-10cm), humidity (by neutron gauge if possible).