Multilocational evaluation of biomass sorghum hybrids under two stand densities and variable water supply in Italy

Sorghum, a C4 plant particularly resistant to drought and high temperatures, is highly competitive amongst biomass crops in dry areas where irrigation water supply is a limiting factor during crop development. This work was undertaken to assess the plant stand density response for the aboveground biomass production in sorghum hybrids under variable regimes of water supply in Italy. The results showed that water stress causes a decrease in dry matter yield to a level yet agronomically interesting. Total dry matter yield versus stand density relationship was dependent on water regime and sorghum genotype. High stand density (20 plants m-2) outyielded the low one (10 plants m-2) under humid conditions whilst the two population stands had statistically comparable biomass yields under water stressed environments. A dichotomous density response was noticed under humid conditions where one group of hybrids (H128, Abetone, ABF14, ABF20, and ABF306) displayed an increasing biomass production while the second one (H132, ABF18, ABF25, and ABF11) had a steady performance in spite of the increasing plant stand.