Determination of cardinal temperatures for sugar apple ( Annona squamosa L.)

Bruno Rafael Alves Rodrigues,Silvia Nietsche,Marlon Cristian Toledo Pereira,Rayane Carneiro Dos Santos,Isabella Renata Gomes Da Cunha,Maria Olívia Mercadante-Simões

doi:10.1590/1413-70542016402039115

Bruno Rafael Alves Rodrigues, Silvia Nietsche + Show 4 more

Open Access

https://doi.org/10.1590/1413-70542016402039115

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Abstract

ABSTRACT The sugar apple is highly dependent on the pollination and fruit tree pollen performance is crucial for successful fertilization and fruit set. The objective of this study was to determine the cardinal temperatures for in vitro pollen grains germination and evaluate the effect of temperature on pollen tube growth of sugar apple. The experimental design was in a completely randomized with eight treatments (10, 15, 20, 25, 30, 35, 40 and 45 ºC), four replicates and each plot was constituted by two slides per parcel. The cardinal temperatures were determined by evaluating in vitro germination of pollen grains and pollen tube growth in standard culture medium. It also assessed the pollen tube growth and the percentage of germination in vitro depending on the type of pollen grain arrangement (monad, dyad, triad and tetrad). In vitro germination of pollen grains and pollen tube growth varied significantly with temperature. The maximum germination recorded (48.13%) and the maximum lengths of pollen tubes (536.45 μm) were obtained when pollen grains were cultivated at 25 ºC. The estimated cardinal temperatures were 9.7, 26.9 and 44.2 ºC. Among the pollen grain arrangements, tetrads pollen grains were observed in higher proportions, however, monads pollen grains presented higher germination percentage.

Highlights

The use of artificial pollination in species of the family Annonaceae, in sugar apple, has significantly increased the productivity of these species
The analysis of variance of the in vitro pollen grain germination and pollen tube length data showed a significant difference at a 1% probability level for the variations in temperature (Table 1)
The results of the present study demonstrate that pollen tube growth was significantly affected by the different temperatures (Table 1)

Summary

Introduction

The use of artificial pollination in species of the family Annonaceae, in sugar apple, has significantly increased the productivity of these species. Our understanding of floral biology and artificial pollination methodologies have advanced in recent years, some of the main obstacles to cultivation are still the low indices of fruit-set of the flowers and their subsequent development into fruit (Mendes et al, 2012; Pereira et al, 2014; Santos et al, 2014). Studies indicate that the low number of carpels fertilized in sugar apple flowers is associated with the low viability of pollen grains during some seasons of the year. The viability of the pollen grains can be affected by various factors, such as plant genotype, nutritional conditions, variation in moisture levels and ambient temperature (Bettiol Neto et al, 2009). Several studies have focused on the effect of temperature during microsporogenesis because the pollen grain is likely to be more sensitive to environmental stress compared to the ovule (Hedhly et al, 2008; Prasad et al, 2011)

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