Associating grouped bar graph with dots connected per line

Question

Good night

I would like to create a secondary y-axis in the graph below where you will plot dots connected per line.

The date.frame I wish to plot on the secondary Y axis is: ATR = c(250,160,250,250)

Below is the data used and an example of how I would like to elaborate the new chart model.

Thank you very much.

TCH <- data.frame(
       Período =c("Jun", "Jul"), 
       CV6654 = c(9.38, 26.14), 
       CTC9002 = c(16.27, 47.71),
       ATR = c(250,160,250,250))

df <- gather(TCH, "Variedades", "Valor", -Período)

ggplot(df, aes(x = factor(Período, levels = c("Jun", "Jul")), y = Valor, fill = Variedades)) +

geom_bar(stat = "identity", position = "dodge") +

geom_label(aes(label = Valor), position = position_dodge(width = 1), show.legend = FALSE) +

scale_fill_manual(values = c("cyan2", "lightgreen")) +

labs(x = "Período", y = "", title = "TCH", subtitle = "Ganho de peso mensal") +

scale_y_continuous(limits = c(0,60)) +

theme_minimal() +

theme(plot.title = element_text(vjust = 1.5, hjust = 0.5), 
    axis.title.y=element_blank(),
    axis.text.y=element_blank(),
    axis.ticks.y=element_blank(),
    axis.text.x=element_text(face = "bold"))