Proceedings of the XLVI Italian Society of Agricultural Genetics - SIGA Annual Congress

Giardini Naxos, Italy - 18/21 September, 2002

ISBN 88-900622-3-1

Poster Abstract - 4.26

BIOMASS, STRUCTURAL CARBOHYDRATES AND LIGNIN EVALUATION IN SORGHUM HYBRID CONSTITUTIONS AND ADVANCED RECOMBINANT INBRED LINES

BERARDO N.*, HABYARIMANA E.**, LORENZONI C.**

*) Istituto Sperimentale per la Cerealicoltura, Bergamo

**) Istituto di Botanica e Genetica Vegetale, Università Cattolica S. Cuore, Piacenza

sorghum, breeding, fiber, energy, feed

Recent biomass sorghum genotypes (Sorghum bicolor L. Moench) were selected to maximize aboveground dry matter production per se irrespective of its quality as to fiber content. As a consequence of breeding for single stalked and lodging resistant genotypes the resulting plant materials display mostly appreciable quantities of lignin-containing fiber ⁽¹⁾. That is unadapted as feed or through fermentation-based industrial usages.

A selection programme for genotype with high level of fermentable organic matter was undertaken starting with two populations deriving from a cross between fiber and sugar sorghum types (LAFF 786 x LP29 and LAFF 789 x LP29).

In order to preliminary evaluate the potentials of this materials, 432 advanced recombinant inbred lines (ARILs) along with twenty-two conventional hybrids at different constitution stages, were compared for total aboveground dry matter, neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin (ADL) performances.

Sorghum materials were evaluated in 2001 at Tadini experimental station in Piacenza (45° 03N; 9° 41E). Experimental plan consisted of randomized complete block design with three replications for hybrids whereas ARILs were raised in two separate nurseries. Harvest was carried out at physiological maturity and the near infrared refrectance spectroscopy (NIRS) was performed to assess sorghum fiber components.

Variability was constantly observed among genotypes as to dry mass, NDF, ADF, and ADL yields. Neither NDF, nor ADF or ADL contents displayed statistical diversity.

Irrespective of dry mass productive capacity, most hybrids showed relatively high lignin-cellulose ratio (0.10-0.12), whilst among high-yielding ARILs, lower values (0.07-0.09) of the ratio showed up.

The absence of correlation between biomass yield and lignin-cellulose ratio suggests a possibility for the breeder to improve sorghum fiber quality while maintaining biomass productive potential.

High - fiber - yielding hybrids and ARILs with low lignin-cellulose ratio were observed whose biomass might be easily digested by ruminants and/or fermented for methane and ethanol conversion purposes.

Those ARILs displaying low lignin over cellulose ratio would be integrated in sorghum breeding schemes.

⁽¹⁾ Bazzocchi R., Moretti C., Conti S., 1997. Indagini sull’attitudine combinatoria di linee di saggina e di linee maschio-sterili di sorgo da granella per la costituzione di ibridi di sorgo da fibra. Sementi Elette 43, 6: 13-19