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research problem that we investigated, and have described here, is the potential interaction between host selection and reproduction by the WTB and resistance of black walnut and butternut. Generally, host selection by bark beetles [Scolytidae (sensu

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reproduction. The objective of this study was to estimate narrow sense heritability in guayule using a method that more accurately accounts for the contributions of apomictic and sexual reproduction. Materials and Methods Open-pollinated seeds, assumed to

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normal sexual reproduction, genetic uniformity and hybrid vigor are lost after the F1 generation, but with apomixis these traits can be maintained through many generations due to a fixed heterozygosity ( Koltunow et al., 1995 ; Ortiz et al., 2013

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triggers stress in flowering crops, and the resulting physiological and ecological responses can have profound repercussions on reproduction, development, and productivity ( Hatfield et al. 2020 ; Lohani et al. 2020 ; Müller and Rieu 2016 ; Zinn et al

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sterility would be expected in the interspecific hybrids of COLE and COTI. However, no studies have been carried to quantify the actual effects of COLE and COTI interspecific hybridization on their progeny’s plant growth, development, and reproduction. This

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A series of experiments on ethylene-insensitive (EI) petunia plants (Petunia ×hybrida Hort. Vilm.-Andr.) generated in two genetic backgrounds were conducted to determine the involvement of ethylene in horticultural performance. Experiments examined various aspects of horticultural performance: days to flower, flower senescence after pollination and without pollination, fruit set and ripening, and adventitious root formation on vegetative stem cuttings. The development of EI plants was altered in several ways. Time from seed sowing to first flower anthesis was decreased by a week for EI plants grown at 26/21 °C. Flower senescence in nonpollinated and self-pollinated flowers was delayed in all EI plants compared to wild-type plants. Fruit set percentage on EI plants was slightly lower than on wild-type plants and fruit ripening on EI plants was delayed by up to 7 days. EI plants produced fewer commercially acceptable rooted cuttings than wild-type plants. There was a basic difference in the horticultural performance of the two EI lines examined due to a difference in the genetic backgrounds used to generate the lines. EI plants displayed better horticultural performance when grown with day/night temperatures of 26/21 °C than 30/24 °C. These results suggest that tissue-specific ethylene insensitivity as well as careful consideration of the genetic background used in transformation procedures and growth conditions of etr1-1 plants will be required to produce commercially viable transgenic floriculture crops. EI petunias provide an ideal model system for studying the role of ethylene in regulating various aspects of plant reproduction.

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The Chilean genus Leucocoryne has exceptional qualities as an ornamental plant that is being developed through breeding. Little is known about the origin of its genetic variation for flower phenotype. Our hypothesis is that, despite having a perfect flower, Leucocoryne has an outbreeding behavior due to self-incompatibility. Greenhouse studies were conducted to study self-incompatibility. In 2000, one species L. purpurea Gay. and two distinct populations Leucocoryne sp. Pichicuy and Leucocoryne sp. Chigualoco were used, whereas in 2001, L. coquimbensis F. Phil. and Leucocoryne sp. Alcones and Leucocoryne sp. Talinay were added. Field studies were carried out in 2001 at La Campana (lat. 29°S, Valparaíso Region, Chile) and Bosque de Fray Jorge (lat. 33°S, Coquimbo Region, Chile) National Parks with L. ixioides Lindley and L. purpurea, respectively. The index of self-genetic incompatibility (ISI) was measured as the average number of seeds per fruit produced by self-pollination divided by the average number of seeds per fruit produced from cross-pollination. The average ISI values for 2000 and 2001 were 0.08 and 0.06, respectively, meaning that Leucocoryne is largely self-incompatible. In the field seed set was compared between flowers that were isolated from insects and those that were not. None of the isolated flowers produced seeds, instead nonisolated flowers produced an average of 29 seeds per fruit at La Campana and 56 at Bosque de Fray Jorge. Leucocoryne's self-incompatibility and outcrossing behavior plus its capacity to fix any genotype via asexual reproduction, most likely contribute to its large variation for flower color, shape, size, design, and aroma. Due to Leucocoryne's reproductive behavior it would be difficult to breed for homozygous inbreds and pure hybrid cultivars

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Insect growth regulators, which are primarily used to kill the larval stages of certain insect groups, have indirect effects on the adult stage of whiteflies. In this study, we assessed the effect of the insect growth regulator novaluron (Pedestal) on the reproduction of silverleaf whitefly (Bemisia argentifolii). Two experiments were conducted by exposing adult female silverleaf whiteflies to the low [0.47 mL·L-1 (6 floz/100 gal)] and high [0.63 mL·L-1 (8 floz/100 gal)] label-recommended rates of novaluron. There was also an untreated control. Infested plants [mist flower (Eupatorium coelenstinum) and transvaal daisy (Gerbera jamesonii) for Expt. 1 and Expt. 2, respectively] containing adult female silverleaf whiteflies were sprayed with novaluron using a carbon dioxide (CO2) backpack sprayer. Plants were immediately placed into cages covered with antivirus insect screening. After 24 hours, six adult female silverleaf whiteflies were aspirated from the treated plants, and immobilized with CO2 before being placed onto untreated plants [transvaal daisy for Expt. 1, and rose-of-china (Hibiscus rosa-sinensis) for Expt. 2]. Three munger cells containing two adult female silverleaf whiteflies per cell were attached to leaves of each of the untreated plants. The number of live and dead eggs, and live nymphs per plant was assessed 4 and 8 days after treatment (DAT). In Expt. 1, the low rate of novaluron significantly reduced egg viability compared to the untreated control based on live nymphal counts 8 DAT. In Expt. 2, both rates of novaluron significantly reduced egg viability compared to the untreated control, based on live nymphal counts and number of dead eggs 8 DAT. The results from this study indicate that novaluron negatively affected female silverleaf whitefly reproduction by reducing egg viability, which may decrease the number of silverleaf whiteflies produced during a cropping cycle. This is an important long-term pest management strategy that may reduce the number of insecticide applications and decrease labor costs.

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as well as composition. Pollen deposition can limit reproduction in many cucurbits ( Robinson and Decker-Walters, 1997 ). Low pollen deposition can result in lighter fruits or fruit abortion ( Stanghellini et al., 1997 ; Stephenson et al., 1988

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along the stem developed as wild-type whereas later developing nodes along shoots again were altered to enact a determinate growth habit. Reproduction. To determine the stability of the phenotype, the plant was asexually propagated using green shoot

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