The influence of agrometeorological factors on the duration of vegetation and yield of green mass of sorghum-sudangrass hybrid ‘Navigator’

Sorghum-sudanass hybrids (SSH) are hybrids of sugar or grain sorghum (Sorghum bicolor (L.) Moench) and Sudanese grass (Sorghum xdrummondii (Steud.) Millsp. & Chase), which have a higher potential compared to the parent forms.  The study of SSH ‘Navigator’ as a new fodder crop for the conditions of the Novgorod region was carried out for eight years (2016–2023) on sod-podzolic medium-cultivated soils. The purpose of the research was to identify the influence of the agrometeorological conditions of the region on the duration of interphase vegetation periods and the yield of the green mass of sorghum-sudangrass hybrid ‘Navigator’. Correlation and regression analysis methods were used to identify the dependencies. According to the values of the hydrothermal coefficient (НTC), of the eight years of testing, three years were arid (НTC –0.98...1.10), one was optimally humid (НTC – 1.37), four were excessively humid (HTC – 1.73...2.65). As a result of the research, a close relationship has been established between the sum of active temperatures and the duration of interphase vegetation periods: “sowing – young growth” (r = 0.94); “sowing – tillering” (r = 0.92); “young growth – tillering” (r = 0.98); “young growth – shooting” (r = 0.96); “tillering – shooting” (r = 0.91). It has been established that the increase in yield is closely related to the amount of precipitation during the “sowing – tillering” period (r = 0.88) and with the hydrothermal coefficient (GTC) during the “sowing – shooting” period (r = 0.70). The revealed dependencies confirm the prospects of promoting the area of sorghum-sudangrass hybrid ‘Navigator’ cultivation as a fodder crop to the North-West of the Non-Chernozem zones of the Russian Federation.