Differential fruitset between grapevine cultivars is related to differences in pollen viability and amine concentration in flowers

Abstract

Background and Aims Reproductive capacity among grapevine cultivars varies considerably and impacts yield. Bioactive amines are reported to be involved in many aspects of plant reproductive physiology. We aimed to examine the association between the reproductive performance of cultivars and the concentration of amines in the reproductive organs. Methods and Results The reproductive performance of Shiraz, Merlot and Cabernet Sauvignon was assessed by determining fruitset, coulure index, millerandage index, pollen tube growth and stigma receptivity. Endogenous concentration of amines in flowers and berries was measured. Poor reproductive performance exhibited by Cabernet Sauvignon and Merlot compared with that of Shiraz was correlated with poor pollen viability. Amine profiles in the flowers and berries varied significantly among cultivars. A significantly higher concentration of diaminopropane was found in Merlot and Cabernet Sauvignon and correlated with a higher proportion of underdeveloped berries. An aromatic amine phenylethylamine was found to be the major free amine in the flowers of Merlot, a cultivar susceptible to poor fruitset. Conclusion Variable reproductive performance exhibited by grapevine cultivars is related to differences in pollen viability and amine concentration in the reproductive organs. Significance of the Study A better understanding of the association between reproductive performance and amines in the reproductive organs of grapevines has been achieved.

Cultivated Grapevine Displays a Great Diversity for Reproductive Performance Variables

“…A mean value of 3.6 was reported by Dry et al[9] for 10 varieties, a lower value than the one found here, likely because of the large number of LGOs found in that study(48.7 LGOs, we found 11.8). Baby et al[23] also found a high Coulure index in Cabernet Sauvignon (5.5), and lower in Merlot (4.2 vs. 5.1 here) and Shiraz (3.3 vs. 1.3 in this work).…”

“…Instead, counting the number of flower caps or calyptras (fused petals) collected in a bag is a non-destructive valid method, because each flower releases one calyptra at blooming [9,17,18,23], which can be delayed. On the other hand, new image analyses tools have been recently developed for estimating the number of flowers from 2D images of the inflorescences, although they have usually been tested in a limited set of varieties [28][29][30][31][32][33].…”

“…Collins & Dry [17] investigated the effectiveness of shoot topping and CCC application on the control of fruitset on Cabernet Sauvignon, Chardonnay and Tempranillo at two sites over two or three seasons. Baby et al [23] examined the association between the reproductive performance of Shiraz, Merlot and Cabernet Sauvignon and the concentration of amines in the reproductive organs.…”

“…In this work, only Katta-Kourgan displayed a Millerandage Index above 4, reaching a mean value of 7.2 (5.4-8.9). Baby et al[23] found a range from 1.4 (Shiraz) to 6.Merlot) and[17] from 1.2 (Tempranillo) to 3.7 (Cabernet Sauvignon). Recently, Wang et al [49] found a Millerandage Index of 1.78 and 2.02 in two seasons in Semillon (1.5-2.7 in this work), and 3.39-4.1 in Shiraz (Syrah, 1.2-1.7).…”

What do we know about grapevine bunch compactness? A state-of-the-art review

“…Recently, it has been suggested that fruitset differences between three cultivars, Shiraz, Merlot and Cabernet Sauvignon, are attributable to differences in pollen viability and in the concentration of diverse amines (e.g. diaminopropane and phenylethylamine) in flowers, which can inhibit pollen tube growth and therefore interrupt the normal fertilisation process (Baby et al ).…”