Viability of maize pollen grains in vitro collected at different times of the day

Abstract

The viability of pollen grains is the essential precondition for obtaining enhanced or hybrid vigor genotypes and a good fixation of the fruit. It is a matter of great importance, especially for genetic improvement programs, which are used in various types of controlled pollination. This study aimed to evaluate the viability of the maize pollen grain through in vitro germination and stainability tests, collected at different times. The experimental design was a randomized block with factorial 2x5, two days of pollination at five times (9:00 a.m., 11:00 a.m., 1:00 p.m., 3:00 p.m. and 5:00 p.m.) with four replications. Each treatment consisted of 12 plants, which were taken randomly within each plot. The parameters evaluated were: germination percentage, the percentage of pollen grain stainability, the stigma receptivity and the best time for pollination. Through the analysis of variance, it was noted and interaction between the days and times of collection and highly significant differences for the following parameters: temperature percentage, humidity, germination and viability of the pollen grain, indicating that the days and times influenced the viability of pollen grains. We could observe that the best results of viable pollen grains were obtained at 09.00 a.m. regardless of the day. It was also noted that the ambient temperature and relative humidity were the main influencing factors on pollen viability, and not the collection times.

Viability and receptivity of reproductive structures in Lima bean (Phaseolus lunatus L.) for improvement programs

“…The quadratic behavior reveals that the highest means of pollen viability are observed in the early hours of the day, with a gradual reduction, reaching the lowest percentage at 1:14 p.m., which corresponds to approximately 81.4% of viable pollen grains (Figure 4). Kaefer et al (2016) also reported a reduction in the viability of maize pollen grains throughout the day. Pollen grain viability is influenced not only by intrinsic factors, such as the physiological maturation stage, origin, and genetic and nutritional traits but also by extrinsic factors, such as temperature and humidity (Stanley & Linskens, 1974;Almeida et al, 2002).…”

“…Temperature and humidity follow a normal variation throughout the day (Figure 1). It is believed that the time effect on pollen viability is directly related to the variation in temperature and humidity, such as that observed for the maize crop, in which a reduction in pollen viability was verified in the hottest hours of the day, with lower humidity, between 11:00 a.m. and 1:00 p.m. (Kaefer et al, 2016). Higher temperatures and lower humidity values were expected late in the morning and in the early afternoon (Figure 1), and the lowest viability percentages were observed at this time, corroborating the data of this experiment.…”

“…Furthermore, pollination is a fundamental step in the production of these plants since it allows the formation of fruits and seeds (Barbosa & Sousa, 2016). The success of pollination will depend on stigma receptivity and pollen viability, which constitute the effective beginning of the pollen-pistil interaction, ensuring the production of seeds of vigorous lineages and/or hybrids in breeding programs (Shivanna, 2003;Kaefer et al, 2016).…”

Modifying the Expression of Cysteine Protease Gene PCP Affects Pollen Development, Germination and Plant Drought Tolerance in Maize

“…Pollen viability was examined with 2,3,5-triphenyltetrazolium chloride (TTC) staining [ 59 ] and I 2 -KI staining methods [ 60 ]. Pollen grains that were stained dark red or orange after 2 h of staining in 0.5% TTC solution were considered viable.…”