我在y轴上有一个带时间（POSIXt）格式值的图。我需要突出显示一个部分但是为了定义矩形值，但我还需要突出显示所有y轴（使一个高亮框覆盖所有y轴）。
DF <- data.frame(DOY = 1:23, Photoperiod =
c("8:52:41","8:53:35","8:54:33","8:55:36","8:56:44","8:57:55","8:59:11",
"9:00:31","9:01:55","9:03:23","9:04:55","9:06:31","9:08:10","9:09:53",
"9:11:40","9:13:30","9:15:23","9:17:20","9:19:20","9:21:23","9:23:29",
"9:25:38","9:27:49"))
DOY Photoperiod
1 08:52:41
2 08:53:35
3 08:54:33
4 08:55:36
5 08:56:44
6 08:57:55
7 08:59:11
8 09:00:31
9 09:01:55
10 09:03:23
11 09:04:55
12 09:06:31
13 09:08:10
14 09:09:53
15 09:11:40
16 09:13:30
17 09:15:23
18 09:17:20
19 09:19:20
20 09:21:23
21 09:23:29
22 09:25:38
23 09:27:49
DF<-as.POSIXct(DF$Photoperiod, format = "%H:%M:%S")
i<- min(DF)
b<- max(DF)
plot(DF, type="l")
box()
rect(4,i,10,b, col= 'lightgreen', density=65)