Selfing in an Alfalfa Seed Production Field

Brown, D. E.; Bingham, E. T.

doi:10.2135/cropsci1994.0011183x003400040050x

Cited by 5 publications

(5 citation statements)

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“…The average individual selfing rate in this study was lower than alfalfa field selfing rate estimates obtained in many previous studies (Burkart, 1937;Johansen, 1963;Bradner and Frakes, 1964;Pedersen, 1968;Knapp and Teuber, 1993;Brown and Bingham, 1994). Conventional wisdom obtained from conversations with alfalfa seed producers states that poorly managed fields are expected to have higher selfing rates.…”

Section: Discussioncontrasting

confidence: 69%

“…pollinator preference for a flower color could have influenced selfing rate estimates (Pederson 1967). Brown and Bingham (1994) used purple flowered "sentinel" plants transplanted into a 0.2 ha seed production field pollinated with alfalfa leafcutter bees and observed a 28% selfing rate. The specialized sentinel plants originated from a separate synthetic population and seeds obtained from these sentinel plants were grown at a separate location (greenhouse) and phenotyped for recessive white flower color progeny segregants to estimate selfing rate.…”

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confidence: 99%

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Selfing Rate in an Alfalfa Seed Production Field Pollinated with Leafcutter Bees

et al. 2015

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A utotetraploid alfalfa (2n = 4x = 32) is the third largest crop by acreage in the United States with an estimated 28 million kg of seed produced per year (NASS, 2009). Although alfalfa tends to outcross (i.e., xenogamous), it is a self-compatible species meaning that self-pollination or "selfing" is possible. Selfing in alfalfa is more likely to occur in the absence of pollen from another genotype, suggesting that, when present, outcross pollen may outcompete self pollen (Viands et al., 1988). Selfing has been shown to occur in insect-pollinated alfalfa seed production fields. Reported field-wide selfing rate estimates range from 9 to 53% (Burkart, 1937, 15% selfing;Johansen, 1963, multiple studies 9 to 26% selfing; Bradner and Frakes, 1964, 34% selfing; Pedersen, 1968, 53% selfing; Knapp and Teuber, 1993, 24% selfing; and Brown and Bingham, 1994, 28% selfing). Most of the pre-1990s studies used white flowered "sentinel" plants in fields of purple flowered alfalfa plants to estimate selfing rates. The pollinators used in these studies varied widely or were not mentioned and ABSTRACT Alfalfa (Medicago sativa L.) self-pollination (i.e., selfing) causes inbreeding depression. Determining factors influencing alfalfa seed production selfing rates could inform potential mitigation strategies to reduce selfing. We measured in situ selfing rates from seed sampled from random plants in a commercial alfalfa seed production field pollinated by leafcutter bees (Megachile rotundata F.). Alfalfa selfing rates were estimated by genotyping ~24 progeny from each of 38 maternal plants. Maternal plant distance to pollinator domicile, pod position on racemes, raceme position on stems, and seeds per pod were noted during seed and tissue collection. Selfing rates averaged 11.8% with individual selfing rates ranging from 0% to 52.2%. Seed from pods collected from upper parts of racemes had lower selfing rates (9.1%) compared to pods from lower parts of racemes (15.1%). When "low" self-compatible (<15% selfing rate in 3+ seeded pods) and "high" self-compatible (≥15% selfing rate in 3+ seeded pods) plants were examined separately, however, this pattern remained significant only for low self-compatible plants (upper raceme selfing rates 3.1% vs. lower raceme 8.3%). Low self-compatible plants had higher selfing rates in 1-2 seeded pods (12.9%) compared to 3+ seeded pods (3.8%) while high self-compatible plants showed no differences in selfing rates based on seed number per pod. Genetic differences for self-pollen's ability to outcompete outcross pollen when growing down the style best explained observed differences between low and high self-compatible plants. Best management practices and selection could help reduce but not eliminate selfing in alfalfa seed production fields.

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Section: Discussioncontrasting

confidence: 69%

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confidence: 99%

Selfing Rate in an Alfalfa Seed Production Field Pollinated with Leafcutter Bees

et al. 2015

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“…One field with a selfing rate of 30% would qualify as having a mixed mating system. Substantial variation in field selfing rates, between 9 and 53% selfing, has been detected in previous studies of alfalfa (Johansen, 1963;Pedersen, 1968;Knapp and Teuber, 1993;Brown and Bingham, 1994;Riday et al, 2015). However, in these studies, the level of selfing was estimated using varying methodologies, which can affect selfing rate estimates (Kehr, 1973;Steiner et al, 1992;Knapp and Teuber, 1993).…”

Section: Discussionmentioning

confidence: 93%

“…Although alfalfa is commonly categorized as an outcrosser, most varieties are self-compatible, meaning that mature seeds are produced under self-fertilization. In alfalfa fields, selfing rate estimates are highly variable and may range from 9 to 47% ( Johansen, 1963 ; Pedersen, 1968 ; Knapp and Teuber, 1993 ; Brown and Bingham, 1994 ; Riday et al, 2015 ). Selfing rate represents the proportion of seeds that result from self-pollination as opposed to outcross pollination (pollen from a distinct plant).…”

Section: Introductionmentioning

confidence: 99%

Self-Fertilization, Inbreeding, and Yield in Alfalfa Seed Production

2021

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Selfing (self-pollination) is the ultimate form of inbreeding, or mating among close relatives. Selfing can create yield loss when inbreeding depression, defined as a lower survival and reproduction of inbred relative to outbred progeny, is present. To determine the impact of selfing in alfalfa (Medicago sativa L.), we quantified the selfing rate of 32 alfalfa seed production fields located in three regions, namely, the Pacific Northwest (PNW), the Central Valley of California (CEV), and the Imperial Valley of California (IMP). Selfing rates (the proportion of selfed seeds) varied between 5.3 and 30% with an average of 12.2% over the 32 seed production fields. In both the parents and their progeny, we observed an excess of heterozygotes relative to Hardy–Weinberg expectations. We detected notable levels of inbreeding in parents (0.231 ± 0.007 parental inbreeding coefficient) and progeny (0.229 ± 0.005). There were a 15% decrease in the number of seeds per stem (seed set) and a 13% decline in the number of seeds per pod in selfed relative to outcrossed stems, but negligible inbreeding depression for pods per raceme and seed weight. The number of racemes on selfed stems increased significantly in fields with greater selfing rates, supporting the presence of geitonogamous or among flower selfing. Despite the significant level of inbreeding depression, seed set did not decrease in fields with higher selfing rates, where the greater number of racemes on the selfed stems increased the seed set. The effects of the field selfing rate on the seed yield metrics were mostly indirect with direct effects of the number of racemes per stem. Available data indicate that the majority of selfing in alfalfa is pollinator-mediated, and thus, eliminating selfing in alfalfa seed production would require the selection of self-incompatible varieties, which, by eliminating inbreeding depression, would provide a 15% potential increase in seed yield and an increase in future hay yield.

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“…Tripping is defined as the release of sexual column which includes style, stigma, part of ovary and 10 stamens, by an explosive force as a string under tension is released. Pollinator inserts it proboscis into the flower throat and exerts pressure among the keel petals to access pollen and nectar [37]. When a flower visitor trips the flower, the pistil and stamens hit the pollinators head, where the pollen get deposited and is dislodged by future tripping's of other flowers [38].…”

Section: Trippingmentioning

confidence: 99%

Reproductive Ecology of Forage Alfalfa (Medicago sativaL.): Recent Advances

Burezq¹

2022

Plant Reproductive Ecology - Recent Advances

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Plants display an assorted collection of reproductive tactics that eventually play a crucial role in perpetuation of species. Plant reproductive ecology is principally concerned with the adaptive implications of the plant in their vicinity, disparity in qualities allied with pollination, seed dispersal, and seedling establishment. The success in reproduction in most flowering plants depends on ecological interactions with pollinators and seed dispersal agents. Modern tactics in reproductive ecology can integrate proper surveys, advanced pollination studies, interaction between flower and pollinators and clear assessments of population genetic structure, which can provide new opportunities for plant reproductive biology. Alfalfa is an important forage legume and known as “Queen of forages” due to its worldwide adaptability, high yield potential and quality. Alfalfa produces seeds which are primarily used for forage production. It is a gift to livestock industry including dairy, beef, horses, and sheep for grazing, silage, hay etc. Alfalfa is also a medicinal herb with antioxidant, antidiabetic, anti-inflammatory, neuroprotective and cardioprotective properties, utilized for treatment of arthritis, kidney problems. The seeds are exploited in alfalfa sprout industry. The current chapter highlights the reproductive biology of alfalfa from flower development to seed production and its advances.

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Selfing in an Alfalfa Seed Production Field

Cited by 5 publications

References 0 publications

Selfing Rate in an Alfalfa Seed Production Field Pollinated with Leafcutter Bees

Selfing Rate in an Alfalfa Seed Production Field Pollinated with Leafcutter Bees

Self-Fertilization, Inbreeding, and Yield in Alfalfa Seed Production

Reproductive Ecology of Forage Alfalfa (Medicago sativaL.): Recent Advances

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