Declining Outcrossing Rates Inside Orchard Blocks of ‘Maluma’ and ‘Shepard’ Avocado (<i>Persea americana</i> Mill.) Trees: Effects on Fruit Yield and Quality
Many rapidly expanding food crops, including avocado (<i>Persea americana</i> Mill.), are dependent on animal pollination but there is a growing shortfall in global pollinator supply. Avocado flowers are insect-pollinated and yields of the main cultivar, ‘Hass’, are often pollen-limited,...
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2025-04-01
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| author | Matthias A. Reese Rachele S. Wilson Joel Nichols Stephen J. Trueman |
| author_facet | Matthias A. Reese Rachele S. Wilson Joel Nichols Stephen J. Trueman |
| author_sort | Matthias A. Reese |
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| description | Many rapidly expanding food crops, including avocado (<i>Persea americana</i> Mill.), are dependent on animal pollination but there is a growing shortfall in global pollinator supply. Avocado flowers are insect-pollinated and yields of the main cultivar, ‘Hass’, are often pollen-limited, especially in the middle of single-cultivar orchard blocks, where there is limited deposition of cross-pollen from another cultivar. We analysed two avocado cultivars of alternate flowering types, ‘Maluma’ (Type A) and ‘Shepard’ (Type B), using SNP-based DNA markers to identify the pollen parent of fruit at different distances from the other cultivar. We aimed to determine whether the numbers of cross-fertilised fruit and tree yields decline at increasing distances from a cross-pollen source, and whether cross-fertilised fruit are larger than self-fertilised fruit. We found that the number of cross-fertilised fruit produced by each tree declined in the middle of the blocks of each cultivar. Trees in the middle of the ‘Maluma’ block compensated for low levels of cross-pollination by producing more self-fertilised fruit, and their yields did not appear to be pollen-limited. However, yields in the middle of the ‘Shepard’ block declined by 25% as a direct result of a 43% reduction in the number of cross-fertilised fruit produced by each tree. ‘Shepard’ trees did not compensate for poor cross-pollination by producing more self-fertilised fruit. Cross-fertilisation of ‘Maluma’ by ‘Shepard’ increased fruit mass by 8% and cross-fertilisation of ‘Shepard’ by ‘Hass’ increased fruit mass by 5%, compared with self-fertilisation. Our results confirm that yields of avocado trees are sometimes, but not always, pollen-limited. Low levels of both self-pollination and cross-pollination resulted in pollen limitation of yield in the middle of the ‘Shepard’ block, but high levels of self-pollination were sufficient to generate high yields in the middle of the ‘Maluma’ block. Closer interplanting of Type A and Type B avocado cultivars increases the opportunities for cross-pollination, which can often increase tree yield and fruit size, and improve the financial returns for growers. Improving the pollination efficiency of foraging insects by providing them with the optimal pollen genotypes is increasingly important as we experience a growing demand for managed pollinators and a declining abundance of wild pollinators. |
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| spelling | doaj-art-b2e7c87b5d3e408f9de2cd99ea5f828d2025-08-20T02:18:15ZengMDPI AGPlants2223-77472025-04-01148121810.3390/plants14081218Declining Outcrossing Rates Inside Orchard Blocks of ‘Maluma’ and ‘Shepard’ Avocado (<i>Persea americana</i> Mill.) Trees: Effects on Fruit Yield and QualityMatthias A. Reese0Rachele S. Wilson1Joel Nichols2Stephen J. Trueman3School of Environment and Science, Griffith University, Brisbane South (Nathan) Campus, Brisbane, QLD 4111, AustraliaSchool of Environment and Science, Griffith University, Brisbane South (Nathan) Campus, Brisbane, QLD 4111, AustraliaSchool of Environment and Science, Griffith University, Brisbane South (Nathan) Campus, Brisbane, QLD 4111, AustraliaSchool of Environment and Science, Griffith University, Brisbane South (Nathan) Campus, Brisbane, QLD 4111, AustraliaMany rapidly expanding food crops, including avocado (<i>Persea americana</i> Mill.), are dependent on animal pollination but there is a growing shortfall in global pollinator supply. Avocado flowers are insect-pollinated and yields of the main cultivar, ‘Hass’, are often pollen-limited, especially in the middle of single-cultivar orchard blocks, where there is limited deposition of cross-pollen from another cultivar. We analysed two avocado cultivars of alternate flowering types, ‘Maluma’ (Type A) and ‘Shepard’ (Type B), using SNP-based DNA markers to identify the pollen parent of fruit at different distances from the other cultivar. We aimed to determine whether the numbers of cross-fertilised fruit and tree yields decline at increasing distances from a cross-pollen source, and whether cross-fertilised fruit are larger than self-fertilised fruit. We found that the number of cross-fertilised fruit produced by each tree declined in the middle of the blocks of each cultivar. Trees in the middle of the ‘Maluma’ block compensated for low levels of cross-pollination by producing more self-fertilised fruit, and their yields did not appear to be pollen-limited. However, yields in the middle of the ‘Shepard’ block declined by 25% as a direct result of a 43% reduction in the number of cross-fertilised fruit produced by each tree. ‘Shepard’ trees did not compensate for poor cross-pollination by producing more self-fertilised fruit. Cross-fertilisation of ‘Maluma’ by ‘Shepard’ increased fruit mass by 8% and cross-fertilisation of ‘Shepard’ by ‘Hass’ increased fruit mass by 5%, compared with self-fertilisation. Our results confirm that yields of avocado trees are sometimes, but not always, pollen-limited. Low levels of both self-pollination and cross-pollination resulted in pollen limitation of yield in the middle of the ‘Shepard’ block, but high levels of self-pollination were sufficient to generate high yields in the middle of the ‘Maluma’ block. Closer interplanting of Type A and Type B avocado cultivars increases the opportunities for cross-pollination, which can often increase tree yield and fruit size, and improve the financial returns for growers. Improving the pollination efficiency of foraging insects by providing them with the optimal pollen genotypes is increasingly important as we experience a growing demand for managed pollinators and a declining abundance of wild pollinators.https://www.mdpi.com/2223-7747/14/8/1218cross-fertilisationcross-pollinationmating system<i>Persea americana</i>polliniserself-compatibility |
| spellingShingle | Matthias A. Reese Rachele S. Wilson Joel Nichols Stephen J. Trueman Declining Outcrossing Rates Inside Orchard Blocks of ‘Maluma’ and ‘Shepard’ Avocado (<i>Persea americana</i> Mill.) Trees: Effects on Fruit Yield and Quality Plants cross-fertilisation cross-pollination mating system <i>Persea americana</i> polliniser self-compatibility |
| title | Declining Outcrossing Rates Inside Orchard Blocks of ‘Maluma’ and ‘Shepard’ Avocado (<i>Persea americana</i> Mill.) Trees: Effects on Fruit Yield and Quality |
| title_full | Declining Outcrossing Rates Inside Orchard Blocks of ‘Maluma’ and ‘Shepard’ Avocado (<i>Persea americana</i> Mill.) Trees: Effects on Fruit Yield and Quality |
| title_fullStr | Declining Outcrossing Rates Inside Orchard Blocks of ‘Maluma’ and ‘Shepard’ Avocado (<i>Persea americana</i> Mill.) Trees: Effects on Fruit Yield and Quality |
| title_full_unstemmed | Declining Outcrossing Rates Inside Orchard Blocks of ‘Maluma’ and ‘Shepard’ Avocado (<i>Persea americana</i> Mill.) Trees: Effects on Fruit Yield and Quality |
| title_short | Declining Outcrossing Rates Inside Orchard Blocks of ‘Maluma’ and ‘Shepard’ Avocado (<i>Persea americana</i> Mill.) Trees: Effects on Fruit Yield and Quality |
| title_sort | declining outcrossing rates inside orchard blocks of maluma and shepard avocado i persea americana i mill trees effects on fruit yield and quality |
| topic | cross-fertilisation cross-pollination mating system <i>Persea americana</i> polliniser self-compatibility |
| url | https://www.mdpi.com/2223-7747/14/8/1218 |
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