No description available.

Dry bean (Phaseolus vulgaris) is a sub-tropical crop severely affected by exposure to low temperatures during all of its growing stages. Cool spring temperatures and the risk of frost are major limiting factors for the early sowing of dry bean in Saskatchewan. Due to its economic importance; however, it has been introduced to Saskatchewan, but it needs to be made more cold tolerant to further expand acreage. The genes that can contribute some tolerance to low temperature stress in bean are not found within the primary gene pool, which limits the capability of breeders to generate a cultivar with such characteristics. Consequently studies have being done in order to find a possible source of genes that can induce tolerance to low temperature exposure. Phaseolus acutifolius is a relative of the domesticated dry bean and previous hybridizations with it have been successful. It is also known to be tolerant to abiotic stresses such as drought. For this reason the decision was taken to explore the level of resistance to low temperature stress exposure in several P. acutifolius accessions. Using whole plant freezing tests in controlled environment chambers, P. acutifolius W6 15578 was found to be more tolerant to exposure to sub-zero temperatures than were P. vulgaris genotypes. Interspecies hybrids were produced between P. vulgaris NY5-161 and W6 15578 and BC2 plants were produced using embryo rescue. The whole plant freezing test is a destructive method that cannot be used with unique F1 and BC2 genotypes, so an alternative methodology to evaluate the hybrids was explored. An electrolyte leakage test was used and showed similar results to the whole plant freezing test with the parent plant controls. The F1 hybrids had an intermediate tolerance to low temperature stress and the further generations (BC1 and BC2) had a better level of tolerance to this kind of stress than the cultivated parent (NY5-161). This suggests that the genes that confer tolerance to low temperature exposure are being maintained through several generations of backcrossing and that these interspecies hybrids may offer a chance for the development of improved dry bean cultivars for the Saskatchewan environment.

Dry bean (Phaseolus vulgaris) is a sub-tropical crop severely affected by exposure to low temperatures during all of its growing stages. Cool spring temperatures and the risk of frost are major limiting factors for the early sowing of dry bean in Saskatchewan. Due to its economic importance; however, it has been introduced to Saskatchewan, but it needs to be made more cold tolerant to further expand acreage. The genes that can contribute some tolerance to low temperature stress in bean are not found within the primary gene pool, which limits the capability of breeders to generate a cultivar with such characteristics. Consequently studies have being done in order to find a possible source of genes that can induce tolerance to low temperature exposure. Phaseolus acutifolius is a relative of the domesticated dry bean and previous hybridizations with it have been successful. It is also known to be tolerant to abiotic stresses such as drought. For this reason the decision was taken to explore the level of resistance to low temperature stress exposure in several P. acutifolius accessions. Using whole plant freezing tests in controlled environment chambers, P. acutifolius W6 15578 was found to be more tolerant to exposure to sub-zero temperatures than were P. vulgaris genotypes. Interspecies hybrids were produced between P. vulgaris NY5-161 and W6 15578 and BC2 plants were produced using embryo rescue. The whole plant freezing test is a destructive method that cannot be used with unique F1 and BC2 genotypes, so an alternative methodology to evaluate the hybrids was explored. An electrolyte leakage test was used and showed similar results to the whole plant freezing test with the parent plant controls. The F1 hybrids had an intermediate tolerance to low temperature stress and the further generations (BC1 and BC2) had a better level of tolerance to this kind of stress than the cultivated parent (NY5-161). This suggests that the genes that confer tolerance to low temperature exposure are being maintained through several generations of backcrossing and that these interspecies hybrids may offer a chance for the development of improved dry bean cultivars for the Saskatchewan environment.

The objective of the thesis is to research the physiological differences between picked genotypes of Capsicum annuum and the effect of lower temperatures in the beginning of ontogeny. Another objective is to find out how Capsicum annuum plants react to application of anti-stress agent Atonic and to determine the most appropriate physiological indicators of resistence to low temperatures. Capsicum annuum ranks among thermophilic crops for which the temperature optimum is of 22 - 25 °C during the day and 18 - 20 °C overnight. They are planted at the field station at the time when ground frost may occur. These can cause physiological changes in the plant or even cause her death. Three varieties were chosen for the experiment: Amy, Eva a Lydia. Plants were divided into a control group and treatment group. Both groups were further divided into two additional groups - with and without the application of Atonic in the beginning of vegetative growth (6th day of exposure to stress). Control group plants were grown at 20 °C and stressed plants were moved into a klimabox with temperature of 5 °C throughout the entire day. Such temperature may occur after planting the plants into an outdoor habitat. Proline content in leaves of Capsicum annuum and relative discharge of electrolyte was studied in two - day intervals. From the obtained results it can be concluded that the accumulation of proline was the highest for Lydia variety in a stressed scenario with the application of Atonic and the lowest proline content was found in in the Amy variety in a control group. Furthermore, it was discovered that the ontogeny of plants has an effect on the accumulation of proline and relative discharge of electrolyte from the beginning of the measurement. The absolute highest electrolyte discharge was measured in the Lydia variety in a stressed scenario and the lowest one was present in the Amy variety in a control group. These results confirm the hypothesis.

Western redcedar (Thuja plicata Donn ex D. Don; redcedar), an indeterminate conifer in the Cupressaceae family, is vulnerable to maladaptation in the face of climate change. Assisted gene flow is one mitigation strategy and involves human-mediated migration of populations, where the projected climate of the area of deployment matches the source climate of the population. Despite the overall projections of warmer temperatures globally, in British Columbia (B.C.), the risk of seasonal frost events will remain and therefore the potential for cold damage and mortality of redcedar exists if the newly migrated populations cannot withstand these freezing events. Knowledge of redcedar's ability to withstand freezing temperatures (cold hardiness) is therefore crucial. Redcedar, like many Cupressaceae species, produces and accumulates the purple-coloured carotenoid rhodoxanthin during the winter. This was hypothesized to be correlated with cold hardiness. Assessment of variation in overall, fall and spring cold hardiness and associated rhodoxanthin concentrations were done through repeated, seasonal freeze testing of clonal grafts originating from across the range of redcedar, and seedling progeny from a subset of these clones. Cold damage was quantified using electrolyte leakage and rhodoxanthin concentrations were quantified using high performance liquid chromatography. Cold hardiness and rhodoxanthin were individually modelled using univariate and bivariate mixed effect models with clone/family as a random effect. Model outputs were compared to climatic variables associated with clonal origin to test for climatic relationships. This study found genetic variation in cold hardiness of redcedar with weak climatic clines. This indicates that assisted gene flow of redcedar should be done on a case-by-case basis, with no need for a climatic threshold. Overall heritability of cold hardiness was 0.17 ± 0.03. Novel findings included the positive genetic correlation between fall and spring cold hardiness (0.55 ± 0.33); lack of reciprocal or parental effect for overall cold hardiness; and weak climatic relationships between cold hardiness and predominantly temperature, with the strongest correlation between number of frost-free days in January (0.38, p < 0.01) in the location of origin and cold hardiness. All findings related to rhodoxanthin were novel. Rhodoxanthin varied with family/provenance and season with heritabilities of 0.30 ± 0.09 in fall, 0.42 ± 0.09 in winter and 0.28 ± 0.09 in spring. Winter and spring rhodoxanthin concentrations were phenotypically correlated (0.50, p < 0.01) and genetically correlated (0.76 ± 0.14). Surprisingly, rhodoxanthin was not detected in clonal grafts of redcedar in any season. Results also indicate that rhodoxanthin cannot be used to estimate cold hardiness. The absence of rhodoxanthin in the clonal grafts compared to the seedlings suggests that plant age impacts rhodoxanthin accumulation. / Graduate / 2021-12-14

Made available in DSpace on 2017-05-12T14:46:48Z (GMT). No. of bitstreams: 1 Flavia.pdf: 1168497 bytes, checksum: f97523b328660e75a0d87b8afe672f21 (MD5) Previous issue date: 2013-02-07 / Beans are one of the foods used to supply the energy needs of the Brazilian diet, so it is necessary that farmers use high seed physiological potential, capable of increasing crop productivity. Thus, the aim of this study was to evaluate the physiological and biochemical changes occurring in beans stored for 360 days. Analyses were performed at 0, 30, 90, 180, 270, and 360 days after receiving the seeds (S1 and S2) and grains (G1 and G2) of BRS Radiance, coming from two producers. Tests of germination, accelerated aging, cold, and index of germination speed (IVG), average length of shoot (CMPA) and of root (CMR), electrical conductivity and the electrical conductivity of the leachate were quantified in levels of sugars and amino acids, in addition to Ca, K, Mg, Mn, Fe, and Zn. The experimental design was completely randomized split-plot in time and the means were compared by the Tukey test at 5% probability. Seed germination was not affected in S2, while S1 and G1 showed a significant fall. The grains from field 1 had a greater influence on heat, stress, and cold, with its vigor decreasing from 91 to 50% and from 93 to 76%, respectively, after 360 days. The IVG tests presented decreased during the experiment. The CMPA and CMR samples showed variations during the experiment, and G1 had the lowest means. In electrical conductivity greater loss of solutes occurred at 90 days of evaluation. Up to 180 days of storage, G1 presented higher amount of amino acids and at 360 days the greatest value S1. Larger amount of soluble sugars were found in samples from field 1. The amount of calcium ions, manganese, iron, and zinc found in the samples were very small. The amounts of potassium decreased until 360 days of storage, and G1 showed the highest value. After 90 days the amounts of magnesium of the samples increased considerably. The grains from field 1 had lower physiological quality. The tests of accelerated aging, cold, and IVG showed a drop in vigor of the Splendor BRS, whereas the electrical conductivity test was not sensitive enough to detect this decrease. This test did not present association with the quantification of the ions investigated. The amount and behavior of amino acids, sugars the ions studied in this work, failed to relate these variables to the decrease in vigor of the bean samples. The storage period influenced the physiological quality of the beans tested. / O feijão é um dos alimentos mais utilizados para suprir as necessidades energéticas da dieta dos brasileiros. Assim, é necessário que os agricultores utilizem sementes de alto potencial fisiológico, capazes de aumentar a produtividade da cultura. Desta forma, o objetivo deste trabalho foi avaliar a qualidade fisiológica e as mudanças bioquímicas ocorridas em feijões armazenados por 360 dias. As análises foram realizadas nos tempos 0, 30, 90, 180, 270 e 360 dias após o recebimento dos lotes de sementes (S1 e S2) e dos grãos (G1 e G2) da cultivar BRS Esplendor vindas de dois produtores. Foram realizados os teste de germinação, de envelhecimento acelerado, de frio, além de índice de velocidade de germinação (IVG), comprimento médio da parte aérea (CMPA) e da raiz (CMR), condutividade elétrica e do lixiviado da condutividade elétrica foram quantificados os teores de açúcares e aminoácidos, além dos íons Ca, K, Mg, Mn, Fe e Zn. O delineamento foi inteiramente casualizado em esquema de parcelas subdivididas no tempo e as médias comparadas pelo teste de Tukey, ao nível de 5% de probabilidade. A porcentagem de germinação não foi afetada para S2, enquanto que nas S1 e G1 a queda foi significativa. Os grãos do campo 1 sofreram maior influência sobre estresse de calor e frio, tendo seu vigor diminuído de 91 para 50% e de 93 para 76%, respectivamente, após 360 dias. O IVG dos testes realizados apresentaram queda durante o experimento. O CMPA e o CMR das amostras apresentaram variações ao longo do experimento, sendo que G1 apresentou as menores médias. No teste de condutividade elétrica maior perda de solutos ocorreu aos 90 dias de avaliação. Até os 180 dias de armazenamento, G1 apresentou maior quantidade de aminoácidos e aos 360 dias S1, o maior valor. Maiores quantidade de açúcares solúveis foram evidenciadas nas amostras do campo 1. A quantidade dos íons cálcio, manganês, ferro e zinco encontrados nas amostras foram muito pequenas. As quantidades de potássio diminuíram até os 360 dias de armazenamento, quando G1 apresentou o maior valor. Após 90 dias, as quantidades de magnésio das amostras aumentaram consideravelmente. Os grãos do campo 1 apresentaram menor qualidade fisiológica. Os testes de envelhecimento acelerado, frio e IVG evidenciaram a queda do vigor da cultivar BRS Esplendor, enquanto que o teste de condutividade elétrica não foi sensível para detectar esta diminuição. Este teste não apresentou relação com a quantificação dos íons investigados. A quantidade e o comportamento dos aminoácidos, açúcares e dos íons estudados não permitiram relacionar estas variáveis com a queda do vigor das amostras de feijão. O período de armazenamento influenciou a qualidade fisiológica dos feijões testados.

Low photosynthetic photon flux density (PPFD) during certain growth periods of cotton (Gossypium hirsutum L.) has been shown to impact yield, ethylene synthesis, and fiber quality. Previous research with shading has shown that lint yield can be significantly reduced in the latter stages of growth. This two-year field study was conducted at the Texas A&M AgriLife Research Farm in Burleson County, Texas, in 2008 and 2009. The study evaluated the impact of an 8-day period of shade (63 percent reduction of PPFD) on cotton yield parameters, fiber quality, and the impact of 1-methylcyclopropene (1-MCP), an ethylene inhibitor, to alter detrimental cotton responses when applied as a foliar spray under shaded and non-shaded conditions. Shade and 1-MCP were imposed at four developmental stages of growth: pinhead square (PHS), first flower (FF), peak flower (PF), and boll development (BD). Data pooled over both years indicated that there were no significant differences in yield for 1-MCP treatments; however, numerical differences existed. Shade applied during the BD stage of development showed significantly lower yield than the untreated control. These results showed a decline in seed cotton and ginned seed cotton by 522 and 207 kg ha-1, respectively. To further analyze further yield components, box-mapping was conducted during both years. However, this data failed to explain consistent patterns of the observed yield responses. Data was also collected to determine the amount of fibers per seed and seed weights. Cotton fiber data did not show consistent correlations with the numerical increases and significant decreases in yield. Electrolyte leakage and stomatal conductance data also were collected. Electrolyte leakage showed no statistical differences when compared to the untreated control. Stomatal conductance measurements showed no consistency for treatments during both years.

Made available in DSpace on 2017-07-10T19:23:36Z (GMT). No. of bitstreams: 1 Flavia.pdf: 1168497 bytes, checksum: f97523b328660e75a0d87b8afe672f21 (MD5) Previous issue date: 2013-02-07 / Beans are one of the foods used to supply the energy needs of the Brazilian diet, so it is necessary that farmers use high seed physiological potential, capable of increasing crop productivity. Thus, the aim of this study was to evaluate the physiological and biochemical changes occurring in beans stored for 360 days. Analyses were performed at 0, 30, 90, 180, 270, and 360 days after receiving the seeds (S1 and S2) and grains (G1 and G2) of BRS Radiance, coming from two producers. Tests of germination, accelerated aging, cold, and index of germination speed (IVG), average length of shoot (CMPA) and of root (CMR), electrical conductivity and the electrical conductivity of the leachate were quantified in levels of sugars and amino acids, in addition to Ca, K, Mg, Mn, Fe, and Zn. The experimental design was completely randomized split-plot in time and the means were compared by the Tukey test at 5% probability. Seed germination was not affected in S2, while S1 and G1 showed a significant fall. The grains from field 1 had a greater influence on heat, stress, and cold, with its vigor decreasing from 91 to 50% and from 93 to 76%, respectively, after 360 days. The IVG tests presented decreased during the experiment. The CMPA and CMR samples showed variations during the experiment, and G1 had the lowest means. In electrical conductivity greater loss of solutes occurred at 90 days of evaluation. Up to 180 days of storage, G1 presented higher amount of amino acids and at 360 days the greatest value S1. Larger amount of soluble sugars were found in samples from field 1. The amount of calcium ions, manganese, iron, and zinc found in the samples were very small. The amounts of potassium decreased until 360 days of storage, and G1 showed the highest value. After 90 days the amounts of magnesium of the samples increased considerably. The grains from field 1 had lower physiological quality. The tests of accelerated aging, cold, and IVG showed a drop in vigor of the Splendor BRS, whereas the electrical conductivity test was not sensitive enough to detect this decrease. This test did not present association with the quantification of the ions investigated. The amount and behavior of amino acids, sugars the ions studied in this work, failed to relate these variables to the decrease in vigor of the bean samples. The storage period influenced the physiological quality of the beans tested. / O feijão é um dos alimentos mais utilizados para suprir as necessidades energéticas da dieta dos brasileiros. Assim, é necessário que os agricultores utilizem sementes de alto potencial fisiológico, capazes de aumentar a produtividade da cultura. Desta forma, o objetivo deste trabalho foi avaliar a qualidade fisiológica e as mudanças bioquímicas ocorridas em feijões armazenados por 360 dias. As análises foram realizadas nos tempos 0, 30, 90, 180, 270 e 360 dias após o recebimento dos lotes de sementes (S1 e S2) e dos grãos (G1 e G2) da cultivar BRS Esplendor vindas de dois produtores. Foram realizados os teste de germinação, de envelhecimento acelerado, de frio, além de índice de velocidade de germinação (IVG), comprimento médio da parte aérea (CMPA) e da raiz (CMR), condutividade elétrica e do lixiviado da condutividade elétrica foram quantificados os teores de açúcares e aminoácidos, além dos íons Ca, K, Mg, Mn, Fe e Zn. O delineamento foi inteiramente casualizado em esquema de parcelas subdivididas no tempo e as médias comparadas pelo teste de Tukey, ao nível de 5% de probabilidade. A porcentagem de germinação não foi afetada para S2, enquanto que nas S1 e G1 a queda foi significativa. Os grãos do campo 1 sofreram maior influência sobre estresse de calor e frio, tendo seu vigor diminuído de 91 para 50% e de 93 para 76%, respectivamente, após 360 dias. O IVG dos testes realizados apresentaram queda durante o experimento. O CMPA e o CMR das amostras apresentaram variações ao longo do experimento, sendo que G1 apresentou as menores médias. No teste de condutividade elétrica maior perda de solutos ocorreu aos 90 dias de avaliação. Até os 180 dias de armazenamento, G1 apresentou maior quantidade de aminoácidos e aos 360 dias S1, o maior valor. Maiores quantidade de açúcares solúveis foram evidenciadas nas amostras do campo 1. A quantidade dos íons cálcio, manganês, ferro e zinco encontrados nas amostras foram muito pequenas. As quantidades de potássio diminuíram até os 360 dias de armazenamento, quando G1 apresentou o maior valor. Após 90 dias, as quantidades de magnésio das amostras aumentaram consideravelmente. Os grãos do campo 1 apresentaram menor qualidade fisiológica. Os testes de envelhecimento acelerado, frio e IVG evidenciaram a queda do vigor da cultivar BRS Esplendor, enquanto que o teste de condutividade elétrica não foi sensível para detectar esta diminuição. Este teste não apresentou relação com a quantificação dos íons investigados. A quantidade e o comportamento dos aminoácidos, açúcares e dos íons estudados não permitiram relacionar estas variáveis com a queda do vigor das amostras de feijão. O período de armazenamento influenciou a qualidade fisiológica dos feijões testados.

Thesis (M. Sc. (Agriculture, Horticulture)) --University of Limpopo, 2016 / ‘Reed’ avocado is a late season cultivar introduced to South Africa from California. The cultivar has shown good adaptation and produces quality fruit with export potential. Its pre-harvest adaptation and production aspects have been researched and documented. However, the effect of harvest time, post-harvest storage and ripening temperature has not been comprehensively studied on this newly introduced ‘Reed’ avocado cultivar. Therefore, the aim of this work was to investigate the effect of different harvest time, post-harvest storage and ripening temperature on the quality of late season ‘Reed’ avocado fruit. Matured ‘Reed’ avocado fruit were harvested based on moisture content indexing in December (2015) and January (2016). The experiment was carried out in a factorial, arranged in a completely randomised design (CRD) with three replicates. Treatment factors were: 2 x harvest time (mid-and late), 2 x post-harvest storage (2.0 and 5.5°C), 3 x ripening temperature (16, 21 and 25°C) and 5 x ripening day (0, 2, 4, 6 and 8). Fruit were stored at 2.0 and 5.5°C for 28 days, thereafter, ripened at 16, 21 and 25°C until fully ripe. During ripening, fruit were evaluated for weight loss, skin colour, firmness, respiration rate, physiological and pathological disorders. Mid-harvest fruit had higher moisture content when compared with late harvest fruit. However, harvest time, post-harvest storage, ripening temperature and ripening time (days) significantly influenced fruit weight loss, firmness, respiration rate, ripening percentage of ‘Reed’ avocado fruit during ripening. Moreover, fruit firmness decreased faster at higher temperatures (25 and 21°C) with fruit ripening within 4 and 6 days, respectively. In addition, ripening at a lower temperature (16°C) was slower with fruit fully ripened within 8 days after withdrawal from cold storage at both harvest times. ‘Reed’ avocado fruit respiration rate followed a climacteric pattern, however, significantly higher rate at higher temperature (25°C) when compared with lower temperature (16°C) after withdrawal from cold storage during both harvest times. Interestingly, mid-harvest fruit showed high electrolyte damage after withdrawal from 2.0°C when compared with late harvest fruit at the same temperature. Furthermore, mid-harvest fruit stored at 2.0ºC and ripened at 21°C showed higher chilling injury when compared with fruit ripened at 16 and 25°C. High electrolyte leakage positively correlated (R2 = 0.242) with high chilling damage for xiv mid-harvest fruit stored 5.5°C. Treatment factors had a significant effect (P < 0.05) on lightness (L *) and hue angle (h ) but no significant effect (P > 0.05) on chroma (C *) and eye colour of ‘Reed’ avocado fruit during ripening, irrespective of harvest time. Overall results showed a visual change in ‘Reed’ avocado skin colour, with eye colour changing from green to bright yellow. Furthermore, late harvest fruit showed high post-harvest pathological diseases after removal from high temperature (5.5°C) when compared with mid-harvest fruit stored at low storage temperature (2.0°C). Ripening at a higher temperature (21 and 25°C) resulted in higher incidence of stem-end rot and body rot when compared with lower temperature (16°C) for both harvest times. Late harvest fruit showed a higher incidence of vascular browning at higher ripening temperatures (21 and 25°C) when compared with lower temperature (16°C) after withdrawal from cold storage. Moreover, overall results showed that harvest time, post-harvest storage and the ripening temperature had a profound influence on the quality of ‘Reed’ avocado fruit. In conclusion, ‘Reed’ avocado fruit can be harvested during mid- or late season and stored at recommended low temperature (2.0ºC); and thereafter, ripened at either 16 or 21ºC. In addition, future studies should focus on identifying pre-harvest practices that promote higher post-harvest fruit quality for ‘Reed’ avocado fruit under South African production environment. Keywords: ‘Reed’ avocado fruit; firmness; electrolyte leakage; respiration rate; stem-end rot; body rot; vascular browning

Tesis por compendio / [ES] En la actualidad, los estreses abióticos son una de las principales limitaciones en la producción agraria y seguridad alimentaria. La búsqueda de estrategias para conseguir una mejor tolerancia a los estreses abióticos es un objetivo de gran interés a nivel mundial, especialmente frente al estrés supra-térmico teniendo en cuenta el escenario de calentamiento global en el cual nos encontramos. Un modo de sortear los estreses ambientales, bajo el prisma de un manejo integrado o ecológico del cultivo, es la utilización de plantas injertadas como estrategia de adaptación. En pimiento, cultivo de gran importancia económica en nuestro país, la menor utilización de la técnica del injerto es debida a la inexistencia de patrones con suficiente adaptabilidad a condiciones de estrés abiótico. En este sentido, el equipo de investigación mixto entre la Universitat Politècnica de València (UPV) y el Instituto Valenciano de Investigaciones Agrarias (IVIA), el cual engloba esta tesis doctoral, ha sido capaz de seleccionar diferentes accesiones e híbridos de pimiento, entre ellos el híbrido NIBER®, que utilizados como portainjertos han obtenido buenos resultados en término de rendimiento en condiciones de estrés hídrico y salino, y generar información respecto a los diferentes mecanismos fisiológicos y moleculares responsables de dicha tolerancia. Sin embargo, hasta la fecha, la información sigue siendo limitada en diferentes sentidos: no se ha estudiado en profundidad el efecto del injerto a las altas temperaturas; no se ha profundizado en el estudio de los mecanismos de tolerancia del portainjerto NIBER® frente al estrés hídrico causado por un riego deficitario controlado; y por último, ningún estudio se ha centrado en analizar los efectos del propio injerto sobre el rendimiento y calidad de los frutos de variedades tradicionales de pimiento. En este sentido, los objetivos que se han planteado en esta tesis doctoral han sido: I) evaluación fisiológica y agronómica de la tolerancia al estrés supra-térmico de accesiones de Capsicum annuum L. utilizadas como portainjertos; II) estudio de los mecanismos fisiológicos que subyacen en el comportamiento de portainjertos tolerantes a estrés supra-térmico; III) estudio de las bases del comportamiento agronómico y fisiológico de portainjertos de pimiento tolerantes a estrés hídrico en condiciones controladas de riego deficitario; IV) evaluación agronómica y de la calidad del fruto de variedades tradicionales de pimiento injertadas sobre patrones tolerantes a estreses abióticos. En esta tesis doctoral, por un lado, hemos sido capaces de seleccionar accesiones de pimiento, especialmente A57, que utilizadas como portainjertos confieren a la variedad injertada cierto grado de tolerancia al estrés térmico por altas temperaturas. También hemos podido comprobar que estos portainjertos tolerantes permiten a la variedad generar respuestas adaptativas a los efectos negativos de este estrés mediante la modificación de su comportamiento fisiológico, disminuyendo la fuga de electrolitos y la acumulación de H2O2, y aumentando el contenido de clorofilas y carotenoides en las hojas. Esta respuesta fisiológica observada en las hojas resulta en una mejor adaptación fisiológica en su fase reproductiva, mejorando el contenido de prolina en las anteras y la viabilidad de los granos de polen, incrementando con ello el cuajado de frutos y en consecuencia el rendimiento comercial. Por otro lado, hemos visto que la tolerancia al estrés hídrico conferida por el portainjerto NIBER® es consecuencia de una modificación fisiológica que permite mantener los niveles de fotosíntesis con una adecuada eficiencia en el uso del agua, resultando en un mayor rendimiento comercial. En este sentido, el uso de la estrategia de riego deficitario combinada con el uso de portainjertos tolerantes al estrés hídrico y con un mayor desarrollo radical, como es el caso del NIBER®, puede considerarse útil para reducir el consumo de agua, amortiguando lo / [CA] En l'actualitat, els estressos abiòtics són una de les principals limitacions en la producció agrària i seguretat alimentària. La cerca d'estratègies per a aconseguir una millor tolerància als estressos abiòtics és un objectiu de gran interés a nivell mundial, especialment davant de l'estrés supra-tèrmic tenint en compte l'escenari de calfament global en el qual ens trobem. Una manera de sortejar els estressos ambientals, sota el prisma d'un maneig integrat o ecològic del cultiu, és la utilització de plantes empeltades com a estratègia d'adaptació. En pimentó, cultiu de gran importància econòmica al nostre país, la menor utilització de la tècnica de l'empelt és deguda a la inexistència de patrons amb suficient adaptabilitat a condicions d'estrés abiòtic. En aquest sentit, l'equip d'investigació mixt entre la Universitat Politècnica de València (UPV) i l'Institut Valencià d'Investigacions Agràries (IVIA), el qual engloba aquesta tesi doctoral, ha sigut capaç de seleccionar diferents accessions e híbrids de pimentó, entre ells l'híbrid NIBER®, que utilitzats com portaempelts han obtingut bons resultats en terme de rendiment en condicions d'estrés hídric i salí, i generar informació respecte als diferents mecanismes fisiològics i moleculars responsables d'aquesta tolerància. No obstant això, fins hui, la informació continua sent limitada en diferents sentits: no s'ha estudiat en profunditat l'efecte de l'empelt a les altes temperatures; no s'ha aprofundit en l'estudi dels mecanismes de tolerància del portaempelt NIBER® enfront de l'estrés hídric causat per un reg deficitari controlat; i finalment, cap estudi s'ha centrat en estudiar els efectes del propi empelt sobre el rendiment i qualitat dels fruits de varietats tradicionals de pimentó. En aquest sentit, els objectius que s'han plantejat en aquesta tesi doctoral han sigut: I) avaluació fisiològica i agronòmica de la tolerància a l'estrés supra-tèrmic d'accessions de Capsicum annuum L. utilitzades com portaempelts; II) estudi dels mecanismes fisiològics que subjauen en el comportament de portaempelts tolerants a estrés supra-tèrmic; III) estudi de les bases del comportament agronòmic i fisiològic de portaempelts de pimentó tolerants a estrés hídric en condicions controlades de reg deficitari; IV) avaluació agronòmica i de la qualitat del fruit de varietats tradicionals de pimentó empeltades sobre patrons tolerants a estressos abiòtics. En aquesta tesi doctoral, d'una banda, hem sigut capaços de seleccionar accessions de pimentó, especialment A57, que utilitzades com portaempelts confereixen a la varietat empeltada un cert grau de tolerància a l'estrés tèrmic per altes temperatures. També hem pogut comprovar que aquests portaempelts tolerants permeten a la varietat generar respostes adaptatives als efectes negatius d'aquest estrés mitjançant la modificació del seu comportament fisiològic, disminuint la fugida d'electròlits i l'acumulació de H2O2, i augmentant el contingut de clorofil·les i carotenoides en les fulles. Aquesta resposta fisiològica observada en les fulles resulta en una millor adaptació fisiològica en la seua fase reproductiva, millorant el contingut de prolina en les anteres i la viabilitat dels grans de pol·len, incrementant amb això el quallat de fruits i en conseqüència el rendiment comercial. D'altra banda, la tolerància a l'estrés hídric conferida pel portaempelt NIBER® és conseqüència d'una modificació fisiològica que permet mantenir els nivells de fotosíntesi amb una adequada eficiència en l'ús de l'aigua, resultant en un major rendiment comercial. En aquest sentit, l'ús de l'estratègia de reg deficitari combinada amb l'ús de portaempelts tolerants a l'estrés hídric i amb un major desenvolupament radical, com és el cas del NIBER®, pot considerar-se útil per a reduir el consum d'aigua, esmorteint els efectes negatius de l'estrés sobre el rendiment, degut principalment a la menor incidència de BER. Finalment, hem sigut capaços de constatar que l'ús de portaem / [EN] Currently, abiotic stresses are one of the main limitations in agricultural production and food security. The search for strategies to achieve a better tolerance to abiotic stresses is an objective of great interest worldwide, especially in the face of supra-thermal stress, considering the global warming scenario in which we find ourselves. One way to overcome environmental stresses, under the prism of an integrated or ecological management of the crop, is the use of grafted plants as an adaptation strategy. In pepper, a crop of great economic importance in our country, the lesser use of the grafting technique is due to the lack of rootstocks with sufficient adaptability to abiotic stress conditions. In this sense, the mixed research team between Universitat Politècnica de València (UPV) and Instituto Valenciano de Investigaciones Agrarias (IVIA), which includes this doctoral thesis, has been able to select different pepper accessions and hybrids, including the NIBER® hybrid, which used as rootstocks have obtained good results in terms of yield under conditions of water and saline stress, and generate information regarding the different physiological and molecular mechanisms responsible for said tolerance. However, to date, the information remains limited in different ways: the effect of grafting at high temperatures has not been studied in depth; the study of the tolerance mechanisms of the NIBER® rootstock against water stress caused by controlled deficit irrigation has not been studied in depth; and finally, no study has focused on analyzing the effects of the graft itself on the yield and quality of the fruits of traditional pepper varieties. In this sense, the objectives that have been set in this doctoral thesis have been: I) physiological and agronomic evaluation of the tolerance to supra-thermal stress of accessions of Capsicum annuum L. used as rootstocks; II) study of the physiological mechanisms that underlie the behavior of rootstocks tolerant to supra-thermal stress; III) study of the bases of the agronomic and physiological behavior of pepper rootstocks tolerant to water stress under controlled conditions of deficit irrigation; IV) agronomic and fruit quality evaluation of traditional pepper varieties grafted on rootstocks tolerant to abiotic stresses. In this doctoral thesis, on the one hand, we have been able to select pepper accessions, especially A57, which, when used as rootstocks, give the grafted variety a certain degree of tolerance to thermal stress from high temperatures. We have also been able to verify that these tolerant rootstocks allow the variety to generate adaptive responses to the negative effects of this stress by modifying its physiological behavior, decreasing electrolyte leakage and H2O2 accumulation, and increasing the content of chlorophylls and carotenoids in the leaves. This physiological response observed in the leaves results in a better physiological adaptation in its reproductive phase, improving the proline content in the anthers and the viability of pollen grains, thereby increasing fruit set and consequently commercial yield. On the other hand, the tolerance to water stress conferred by the NIBER® rootstock is the consequence of a physiological modification that allows maintaining photosynthesis levels with an adequate water use efficiency, resulting in a higher commercial yield. In this sense, the use of the deficit irrigation strategy combined with the use of tolerant rootstocks to water stress and with greater root development, as is the case of NIBER®, can be considered useful to reduce water consumption, cushioning the negative stress effects on yield, mainly due to the lower incidence of blossom-end rot (BER). Finally, we have been able to verify that the use of tolerant rootstocks to abiotic stresses, such as NIBER®, in traditional pepper varieties could be a useful technique to improve the yield and commercial quality of this crop, mainly by reducing the incidence of BER, / Esta tesis doctoral ha sido realizada gracias a la financiación del Ministerio de Ciencia e Innovación (MCIN/AEI/10.13039/501100011033) mediante los proyectos RTA-2017- 00030-C02 y PID2020-118824RR-C2, y a la financiación del Ministerio de Universidades a través de un contrato predoctoral FPU (FPU18/00564) / Gisbert Mullor, R. (2023). Análisis de la variabilidad genética del género Capsicum frente a estreses abióticos para su uso como portainjertos. Estudio de los mecanismos fisiológicos de tolerancia, del comportamiento agronómico y de la calidad del fruto [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/196652 / Compendio