In an angiosperm, male plant is diploid and female plant is tetraploid then endosperm will be

If a male plant is diploid (2n) it will produce haploid male gamete (n). If a female plant is tetraploid (4n) it produces tetraploid secondary nucleus or diploid polar nuclei (2n, 2n). Endosperm is formed by fusion of male gamete with two polar nuclei, i.e. fusion of two diploid polar nuclei and haploid male gamete will give pentaploid (5n) Primary endosperm nucleus and eventually pentaploid endosperm.