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Content of alkenylglucosinolates in the seed of Brassicaceae
1990
Voskerusa, J. (Vyzkumna Stanice Olejnin, Opava (Czechoslovakia))
Analisis de la composicion en trigliceridos del aceite de las semillas de algunas especies del genero Brassica (Brassicaceae).
1990
Vioque J. | Pastor J. | Vioque E.
Se ha estudiado la composicion en trigliceridos de aceites de semillas de cuatro especies del genero Brassica (Brassicaceae). Se ha encontrado un predominio de los trigliceridos triinsaturados (entre el 80,10% y el 85,76%). Asi mismo, el acido erucico, caracteristico de las Brassicaceae, se hallo en la mayoria de los trigliceridos (entre el 75,80% y el 94,61%). En las cuatro especies encontramos como trigliceridos mayoritarios 1,3-dieruci-2-linolenina (pentainsaturado) y 1,3-dieruci-2-linoleina (tetrainsaturado).
Show more [+] Less [-]Efficacy of post-emergence herbicides for weed control in chemical fallows in Southern Queensland
1990
Pope, V.A. | McConville, P.N. (Queensland Dept. of Primary Industries, Toowoomba (Australia). Wheat Research Inst.)
Out-of-patent herbicides (2,4-D, MCPA, dichlorprop, amitrole, ametryn, atrazine and linuron) were screened at 3 rates of post-emergence application for weed control during fallow periods in southern Queensland. Herbicide efficacy was assessed on 26 weeds at 1 or more stages of growth. Each herbicide had a limited spectrum of activity over the range of species encountered, with amitrole being the most effective. The chlorophenoxy compounds controlled only some of the broad-leaved species and had no effect on grass species. Most herbicides were ineffective on large weeds. The rate of herbicide application also influenced the level of activity on most species. Most of the weeds in the Brassicaceae group were susceptible to all rates of the chlorophenoxy herbicides.
Show more [+] Less [-]Influences of Floral Variation on Pollen Removal and Seed Production in Wild Radish Full text
1990
Young, Helen J. | Stanton, Maureen L.
The effects of corolla size, pollen production, and pollinator visitation frequency on pollen removal (an estimate of male reproductive success) and pollen deposition and seed production (female success) were studied in wild radish (Raphanus sativus, Brassicaceae) in 1987. Wild radish exhibits variation in corolla size, petal coloration, and anther size. A previous study (Stanton and Preston 1988) found no correlation between corolla size and estimates of female success, suggesting that flower size may be selected upon through variation in male reproductive success. For flowers receiving a single honey bee visit, corolla size was positively correlated with pollen removal, but not with pollen deposition on stigmas or seed production. Flowers receiving an average of 3.7 honey bee visits (in the 1987 study) also showed a correlation between corolla size and pollen removal (seed production was not monitored in this study). In contrast, when flowers were visited an average of 5.7 times by honey bees (the 1988 study), there was no significant relationship between corolla size and either pollen removal or estimates of female reproductive success (pollen deposition on stigmas and seed production). Honey bees demonstrated a preference for large flowers, either by significantly overvisiting large flowers or by visiting the large flowers, before visiting smaller flowers. Under natural conditions, most radish flowers receive numerous visits, but even with frequent visitation, at least 20% of the pollen a flower produced was not removed. At the same time, flowers with greater pollen production had a larger proportion of pollen removed. Pollen removal was a positive decelerating function of honey bee visitation frequency. The number of pollen grains removed per visit declined with increasing honey bee visits. The male fitness function (pollen removal plotted against pollen production) was positive and decelerating in two experiments; positive and linear in one study. Large flowers may have greater male success than small flowers by virtue of their greater pollen production, their greater pollinator visitation frequency, and their earlier pollinator visitation. If selection is acting on floral traits in wild radish through variation in male success, increases in both corolla size and pollen production are likely to be selected for.
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