what is the stacking reward look like ? why the masternodes reward are so low ?
Stacking reward? We aren't POS so if I understand your question there isn't a stacking reward.
To keep the rewards fair the block reward split is 45% miners/45% masternodes/10% decentralized governance.
Looks like the ROI is about 27% right now, which obviously doesn't include price growth. You can check in depth real time stats here: https://masternode.terracoin.io/stats.php
Our goal is to be long term, stable and guided by decentralized governance, not just a quick buck flash in the pan coin.
You should check out the white paper and the weekly update with The Terracoin Foundations vision.