Meteorological Influences on Pheno-Morpho-Yield Data of Grain Sorghum Varieties in Central Italy

Sorghum (Sorghum bicolor L. Moench) is widely grown in many arid and semiarid areas of the world due to its ability to yield well under rainfed or water-limited conditions. In the present study some sorghum varieties (medium-long season) have been studied in relationship with the principal meteorological variables considering also the drought effect in a favorable groundwater situation. The phenological adaptation, morphological and productive features during 11 yr of investigations from 2005 to 2015 in central Italy were evaluated. In the study area the soil water availability from emergence to flowering was high for all the varieties development considering that no significant phenological differences were evidenced also after flowering between the groups of sorghum cultivars. The plant vegetative development and in particular the flag leaf height was influenced by the low precipitation volumes recorded during 2007 and 2015 spring periods such as plant height particularly affected by extremely low rain volumes from May to July during the last study year. Moreover, seed numbers may be reduced if drought stress occurs immediately after seed set as a result of embryo abortion and the quite absent precipitations during summer 2007 (above all during August when average sorghum flowering is recorded) resulted in a reduction of kernel weight for almost all the varieties. The highest groundwater depth (conditioned by low precipitation volumes) recorded during 2015 determined a high water stress that may have influenced above all panicle size and consequently the number of seeds per panicle.