words - しな at the end of a sentence

In the manga Yotsubato, the main character Yotsuba's father says 「ジャンボが二人分働くしな」. I understand the sentence as a whole, I think, but I don't understand the しな at the end.

Here's the full dialogue:

よつば：ジャンボ、しばらく見ないうちにまた大きくなった！
ジャンボ：お？どこでおぼえたそのセリフ

お父さん：まあいいか。ジャンボが二人分働くしな

Answer