Don't use that - it will get rejected for lighting and composition. There's a large expanse of dark background and wet lime plunked dead center.

Have a look through other threads on this topic (applying to iStock) but you'll need three images of different types/subjects (for example, one portrait, one outdoor/landscape and one studio shot). Good focus, no noise/artifacts, stay away from extreme post processing, no flowers, kittens, puppies or sunrise/sunsets.

I agree with the above. I'm afraid you're some way off with a shot like this.
As well as the above comments, try to show that you understand how to show some sort of concept in the shots if possible. Don't just take shots of people doing nothing, or random shots of objects.
I'd also have a look at the critique forum on iStock if I were you. There are lots of fairly recent threads about images for acceptance.

It's a snapshot of a lime? To me the white balance and exposure look off. It's dull. Not punchy. Stock photos are used to sell something. Like a lime drink. If you saw a Sprite advertisement using this lime what would you think?

A search for lime on Istock gets 18,755 results. Shutterstock gets 60,578 results. I'd suggest checking those out and comparing yours to the tens of thousands of competitors. What's better about yours? What's unique? Why would a buyer choose yours over the tens of thousands of others?

When you improve camera basics like exposure/white balance and then understand what buyers want then you'll have something to submit.