Pollen morphological research of guava cultivars under South Gujarat condition

Pollen morphological research in guava are important for understanding the reproductive biology, genetic diversity, and evolutionary relationships of guava. Pollen morphology can also provide insights into the compatibility of different guava cultivars for breeding programs and therefore an investigation of different six guava cultivars; i.e., Yogi, Sanjari, Exotica, VNR 1 kg, Lalit and Sardar (L-49) was conducted under South Gujarat condition for quantitative characteristics such as length of the polar axis (P), equatorial diameter (E) and P/E ratio, and qualitative characteristics; polarity, size, shape and aperture of the pollen grains. The results demonstrated that all the cultivars had isopolar pollen grains with tricolporate and tetracolporate apertures. The pollen grains were small (less than 25 m) to medium (between 25 and 50 m) in size. Compared with the small pollen grains of the remaining types, Lalit produced pollen grains of two sizes: small (85.83%) and medium (14.17%). The equatorial diameter and polar axis of the pollen varied significantly among guava cultivars, ranging from 18.81 μm (Sardar) to 21.60 μm (Lalit) and from 21.21 μm (Sardar) to 25.67 μm (Lalit), respectively. The P/E ratio of the pollen grains varied from 1.12 (Lalit) to 1.25 (VNR Bihi). Pollen is produced by all guava types in five different shapes: spherical, prolate-spheroidal, subprolate, oblate-spheroidal and prolate. However, among all the pollen morphologies, the prolate-spheroidal type was the best. The measurement ranges for germination rates and pollen viability were 72.50–92.96% and 60.16–79.52%, respectively. On the other hand, the Sardar and Lalit cultivars presented greater pollen germination and pollen viability, respectively, than the other guava cultivars did.