The Effect of Harvest Time on Macro Nutrient Concentrations in Sorghum x Sudangrass Hybrid and Sudangrass Varieties

In this study, it was aimed to determine the effect of harvest time on some mineral contents in sorghum x sudangrass hybrids (Sorghum bicolor x Sorghum sudanense Stapf) and sudangrass [Sorghum sudanense (Piper) Stapf] cultivars grown as a second crop. In this research, field trials were conducted under semi-arid climate conditions of Diyarbakır province in Turkey. Plant material of the research was consisted of "Sugar Graze-II" and "Nutri-Honey" sorghum x sudangrass hybrid varieties and "Gözde-80" sudangrass variety. As the harvest time, completely blooming, milk stage and dough stage were chosen. Field trials were designed as divided parcels in randomized complete blocks design with 4 replications. According to results of the research, significant differences were determined between the varieties for phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg), and Nutri-Honey sorghum x sudangrass hybrid was the richest (0.35% P, 2.11% K, 0.56% Ca and 0.19% Mg) in terms of mineral content. As the harvest time is delayed, it was determined that the P, K and Mg amounts in the plants decreased, while Ca rates were increased. As the average of two years data, the highest P (0.34%), K (2.26%) and Mg (0.18%) values were obtained in the completely blooming period, and the highest Ca rate was obtained from the plants harvested in the milk stage (0.55%) and dough stage (0.58%). Sorghum varieties were sufficient to meet the needs of animals in terms of forage K content; however, P, Ca and Mg ratios were below the limit values that should be in feed rations. Ca/P ratio did not pose any risk for animal health in terms of both cultivars and harvest times. As a result of the research, K/(Ca+Mg) ratios varied between 1.80-3.72 according to cultivar and harvest times, and sorghum varieties with an average K/(Ca+Mg) ratio of 2.71 were found to have a risk of tetanic disease in terms of animal health. According to these results, if the sorghum varieties are used for roughage alone, it will be appropriate to add P, Ca and Mg substances to feed rations and/or to use sorghum in animal feeding with these minerals rich feeds.