Traditionally, gender identification of date palm can be done by phenotypic characters of flowers of date palm. Additionally, for developing flowers, date palm plant takes 4–8 years for flower development depending on environmental conditions and after appearance of flower, male and female separation can possible. The shape of spathe is swollen or bloated near the distal end and larger and shorter than female date palm before emergence of the inflorescence. The male flower also having noticeable petals, stamens and prolific pollen and producing fragrance at the pollen release time.
For the economic production of date palm, farmers have to maintain desired population of gender specific date palm plants. For this, early sex identification is crucial step. There are many researchers tried hard to solve the complex puzzle by using various methodology. Siljak-Yakovlev et al (Siljak-Yakovlev et al. 1996) used cytological methods, but it needs advanced instrument facilities. Abdul et al (Khan et al. 2021), used nuclear magnetic resonance (NMR) spectroscopy, Near-Infrared Reflectance Spectroscopy (NIRS) and Fourier transform infrared attenuated total reflectance (FTIR/ATR) methods to identify the sex differentiation in immature date palm leaves. However, for performing this experiment, also required sophisticated costly instruments. The PCR based molecular technique of date palm sex determination is not affected by age, environment and reproductive stage of plant. Same technique also used by Intha and Chaiprasart (Intha and Chaiprasart 2018), for gender identification of date palm of cv. KL1 of Thailand.
The gender identification of date palm by gender specific marker was also tried by Al-Mahmoud et al (Al-Mahmoud et al. 2012) and Solliman et al (EL-Din Solliman et al. 2019), but they did not include Gujarat date palm cultivars. Additionally, we also used SRY primer suggested by Solliman et al (EL-Din Solliman et al. 2019), but it cannot distinguish sex of date palm of Gujarat cultivars. This experiments, hence, showing its importance on various date palm cultivars grown by farmers.
The sex determination of seedlings at early stage could help to improve breeding efforts by generating experimental gender specific genetic pools that will promote date palm genetic improvement (Bekheet and Hanafy 2011). It was reported that GPAT, Glycerol-3-Phosphate Acyltransferase 3 (OsGPAT3), shows a central role in rice male fertility. Mutation in GPAT (osgpat) leads to defective anther cuticle and pollen exile formation in Rice (Men et al. 2017). The repeatability of the GPAT and LOX5.1 primer were tested in 315 date palm samples from Gujarat with known gender. After data analysis, chi square value is 0.26 which shows a difference between observed and expected value and p-value is 0.809 which shows that observed and expected results are almost same. In this experiment, GPAT3 and LOX5.1 primer can distinguish male and female date palm samples based on the presence of a 450 bp and 156 bp sized amplified band. If only 150 bp sized band is present, then its female and if both 450 bp and 156 bp bands are present then it is male sample. Hence, the presence or absence of the GPAT3 amplified band could allow male and female plants to be identified at the seedling stage.