What is ploidy of microspore tetrad cells?

Microspore tetrad cells are the microspores arranged in a group of four. Microspores are formed from microspore mother cell (MMC). MMC is a diploid cell which undergoes meiosis to form four haploid microspores which are arranged in a tetrad. This process is known as microsporogenesis. Each of these four microspores develops into a pollen grain.

Hence, ploidy of microspore tetrad cells is haploid.