RESUMO A cana-de-açúcar (Saccharum spp.) é uma cultura importante devido à produção de açúcar, etanol e bioenergia. Seu cultivo ocorre em regiões tropicais, sendo muitas vezes exposta a alta salinidade. O objetivo foi identificar cultivares tolerantes à salinidade para permitir o cultivo da cana-de-açúcar (Saccharum spp.) em solos salinos. Para testar a hipótese de que a cana-de-açúcar apresenta variação genotípica natural para tolerância à salinidade, testamos dez cultivares (SP80-3280, RB855453 RB966928, RB855156, SP80-1842, SP80-1816, RB928064, RB867515, RB92579, RB855536) e duas espécies de cana-de-açúcar: IM76-228 (S. robustum) e IN84-82 (S. spontaneum) sob duas concentrações de sódio: controle [concentração encontrada naturalmente no solo utilizado: condutividade elétrica de 0,083 dS m-1] e solo enriquecido com NaCl: CE de 7,2 dS m-1. Características de biometria e fotossíntese foram avaliadas. As plantas foram coletadas, separadas em folha (MSF), caule (MSC), raiz para determinação da matéria seca total da planta e assim estimar o índice de tolerância (IT). Uma análise de cluster foi feita para identificar a dissimilaridade fenotípica. Três grupos distintos em relação à tolerância à salinidade com base na biomassa foram formados. As cultivares RB855156, SP80-1842, SP80-1816 e espécies IM76-228 não apresentaram redução em MSF e MSC. No entanto, as cultivares SP80-3280, RB928064, RB92579 e as espécies IN84-82 foram prejudicadas pela salinidade. O genótipo SP80-1816 apresentou o maior acúmulo de biomassa e o maior IT. Portanto, encontramos uma grande variação genotípica quanto à tolerância à salinidade em cana-de-açúcar, que pode ser explorada pelos produtores para cultivo em solos salinos. Também podem ser utilizadas pelos Programas de Melhoramento da Cana-de-Açúcar para melhorar a tolerância à salinidade.

ABSTRACT Sugarcane (Saccharum spp.) is an important crop due to sugar, ethanol and bioenergy production. Its cultivation may occur in tropical regions exposed to high salinity. The aim was to identify cultivars tolerant to salinity to allow the cultivation of sugarcane (Saccharum spp.) in saline soils. To test the hypothesis that sugarcane show natural genotypic variation to salinity tolerance, we tested ten cultivars (SP80-3280, RB855453 RB966928, RB855156, SP80-1842, SP80-1816, RB928064, RB867515, RB92579, RB855536) and two sugarcane species: IM76-228 (S. robustum) and IN84-82 (S. spontaneum) under two concentrations of sodium chloride (NaCl): control (concentration found naturally in the soil used: electrical conductivity of 0.083 dS m-1) and soil enriched with NaCl: EC of 7.2 dS m-1. Biometry and photosynthesis traits were evaluated. The plants were collected and leaf (LDM), stem (SDM), root and total dry matter were used to estimate the tolerance index (TI). A cluster analysis was done to identify phenotypic dissimilarity. Three distinct groups regarding salinity tolerance on biomass-basis were formed. The cultivars RB855156, SP80-1842, SP80-1816 and species IM76-228 showed no reduction in LDM and SDM. Nonetheless, the cultivars SP80-3280, RB928064, RB92579 and species IN84-82 were impaired by salinity. The cultivar SP80-1816 showed the highest biomass accumulation and the highest TI. Therefore, we found a great genotypic variation regarding salinity tolerance in sugarcane, which can be explored by growers to cultivate in saline soils. Also can be used by the Sugarcane Breeding Programs to improve the salinity tolerance.

ABSTRACT Salinity is recognized as one of the main abiotic stresses, causing declines in the productivity of many crops, such as rice. Considering the importance of rice as a staple food crop, the generalized pattern of salinization in soils around the globe and the sensitivity of the crop to saline soils, the aim of this study was to evaluate the sensitivity / tolerance of upland rice lines. The upland rice lines used in this work were obtained from the Genetic Improvement Program of the Universidade Federal de Lavras. The experiment was carried out in a greenhouse, with a block design and factorial scheme, with 10 lines and four NaCl treatments (0, 3, 15 and 45 mmol·L-1) on the substrate. Parameters related to the emergence rate, seedling survival rate, growth and architecture, biomass allocation, gas exchange and productivity were evaluated. Salinity levels influenced the emergence and survival rates, especially at the highest levels of NaCl, with lines L1, L4 and L5 showing survival below 60%. These lines were excluded from the experiment, and the other seven lines were carried out until the end of the crop cycle. Grain weight per plant (GWP) was used as an indicator of greater tolerance to salinity, and lines L6, L7 and L8 showed outstanding performance under treatments with increased NaCl. L6 had the highest GWP, while L7 and L8 had less pronounced decreases with increasing NaCl doses. These three lines may be recommended for further studies about the impacts of NaCl on rice production.

RESUMEN La injertación se considera una herramienta eficaz para contrarrestar múltiples factores bióticos y abióticos que limitan la producción del tomate. Esta técnica consiste en utilizar una planta vigorosao resistente (portainjerto) para reemplazar el sistema radical de un genotipo de interés económico (vástago) pero susceptible a uno o más factores de estrés. Este trabajo tuvo como objetivo evaluar la respuesta fisiológica y productiva de un vástago comercial de tomate injertado en diferentes patrones bajo condiciones de la región altoandina de Colombia. Para este propósito, el cultivar de tomate Libertador fue injertado sobre dos patrones comerciales de tomate ("Olimpo" y "Armada") en un diseño experimental de bloques completos al azar con cuatro repeticiones. Se evaluaron cuatro combinaciones de copa-portainjerto: portainjerto de vigor, portainjerto resistente, auto injertación y plantas no injertadas. La fotosíntesis neta, la tasa de transpiración, la conductancia estomática, el uso eficiente del agua y el uso eficiente de la radiación se evaluaron durante seis etapas fenológicas (701, 704, 706, 708, 710 y 712), según la escala BBCH, mientras que el índice de área foliar y el rendimiento cuántico fueron analizados en cinco etapas fenológicas (excepto 706). Los valores más altos de fotosíntesis neta, conductancia estomática, uso eficiente del agua y uso eficiente de la radiación se registraron en la fase inicial de la etapa de producción (701), con una reducción al final del ciclo de vida del tomate (712). Aunque el tratamiento vigor presentó la menorfotosíntesis neta, este fue superior en términos de índice de área foliar, materia seca de hojas y rendimiento de frutos de tomate. Los valores del rendimiento cuántico del fotosistema II no indicaron lesiones fotoquímicas en ninguna de las combinaciones de injerto y portainjerto. El mayor rendimiento de frutos se alcanzó con el uso de un portainjerto de vigor y se asoció con una acumulación más significativa de materia seca en la hoja y un mayor índice de área foliar.

ABSTRACT Grafting is an effective approach to improve tomato yield and for tolerance to various abiotic and biotic stresses. This technique consists of using a vigorous or resistant plant (rootstock) to replace the root system of a genotype of economic interest (scion) but susceptible to one or more stress factors. The present work aimed to evaluate the physiological and productive response of a commercial tomato scion grafted on different rootstocks in Colombia's high-Andean region. For this purpose, a tomato cv. Libertador was grafted on two commercial ("Olimpo" and "Armada") tomato rootstocks in a randomized complete block experimental design. Four scion×rootstock combinations were evaluated by vigor rootstock, resistant rootstock, self-grafting, and non-grafted plants. Net photosynthesis, transpiration rate, stomatal conductance, water use efficiency, and radiation use efficiency were evaluated during six phenological stages (701, 704, 706, 708, 710, and 712), according to the BBCH scale; while the leaf area index and quantum yield were analyzed in five phenological stages (except 706). The highest values of photosynthesis, stomatal conductance, water and radiation use efficiency were registered in the initial phase of the production stage (701), which tended to decline at the end of the life cycle (712). Transpiration rate was similar throughout the growth cycle. Nevertheless, vigor rootstock presented the lowest photosynthesis rate; it was superior in terms of leaf area index, leaves dry matter, and tomato yield. The quantum yield values of the photosystem II did not indicate photochemical injuries in any of the scion×rootstock combinations. The higher tomato yield was reached in vigor rootstock and was associated with a more significant accumulation of dry matter in the leaf and higher leaf area index.

RESUMO O feijão comum (Phaseolus vulgaris L.) é uma leguminosa importante por ser fonte de proteína, carboidratos e rico em vários minerais. Em situação de alagamento, a disponibilidade de oxigênio pode proporcionar uma condição de anoxia ou hipóxia. O presente trabalho teve como objetivo avaliar o comportamento da cultivar BRSMG-Uai submetida a hipóxia em diferentes fases fenológicas, analisando as respostas em relação ao crescimento e produção, metabolismo de carboidratos e assimilação de nitrato. Desta maneira, sementes de feijão comum foram semeadas e ao atingirem o estádio de desenvolvimento V1 foram transferidas para recipientes contendo 40L de solução nutritiva e aeração constante. As plantas foram expostas a condição de falta de aeração por 9 dias, em três diferentes fases fenológicas. Foram consideradas as fases fenológicas V3/V4, R6 e R7. Após as coletas foram realizadas análises bioquímicas e de crescimento, com delineamento inteiramente casualizado (n=6). Plantas submetidas a baixa disponibilidade de oxigênio apresentaram redução no número de grãos, sendo em V3/V4 a maior perda em produção conferindo maior sensibilidade a hipóxia nesta fase. Em contrapartida, ocorreu aumento na concentração de açucares nas folhas. Foi possível observar nas folhas e raízes, aumento no conteúdo de peróxido de hidrogênio, redução da atividade da enzima dismutase do superóxido nas fases fenológicas V3/V4, R6 e R7, aumento da atividade da enzima peroxidase do ascorbato nas raízes em R6 e da atividade da enzima redutase do nitrato. Conclui-se que a cultivar BRSMG-Uai apresentou sensibilidade a baixa disponibilidade de oxigênio, e que a fase fenológica V3/V4 é a mais crítica.

ABSTRACT Common bean (Phaseolus vulgaris L.) is an important source of protein and carbohydrates, besides being rich in several mineral nutrients. In a flooding situation, the low availability of oxygen may result in hypoxia or anoxia condition. Therefore, this study aimed to evaluate the responses of the common bean cultivar BRSMG-Uai subjected to hypoxia in different phenological phases, analyzing its responses in terms of growth, productivity, carbon and nitrogen metabolism. Thus, seeds of common beans were germinated and when the seedling reached growth stage V1, they were transferred to plastic boxes containing 40L of nutritive solution with steady aeration. Distinct series of plants were exposed to air-restriction on their roots for nine days, in three different phenological phases V3/V4, R6 and R7. Samples were collected for biochemical and growth analyses in a completely random design (n=6). The plants subjected to low availability of oxygen presented a reduction in bean number, displaying the greatest loss in productivity in V3/V4, conferring the highest sensitivity to hypoxia in this phase. On the other hand, there was an increase in sugar concentration in leaves, and it was also possible to observe an increase in hydrogen peroxide in leaves and roots, concomitant with a decrease in superoxide dismutase activity in all phenological phases. There was also an increase in ascorbate peroxidase activity in roots in R6, as well as in nitrate reductase activity. We conclude that the cultivar BRSMG-Uai presents sensitivity to low oxygen availability, and the phenological phaseV3/V4 is the most critical for it.

RESUMO O herbicida lactofen vem sendo utilizado por produtores nas mais diversas condições, visando aumentar a produtividade da soja. Objetivou-se estudar a influência de lactofen e do fito-hormônio cinetina nos caracteres morfoagronômicos, partição de carboidratos e produtividade, em cultivares de soja. Foram conduzidos três experimentos em campo, além de um experimento em casa-de-vegetação. Utilizou-se delineamento em blocos casualizados, com quatro repetições. Os tratamentos foram: lactofen [144 g ha-1 de ingrediente ativo (i.a.)], lactofen + cinetina (144 g ha-1 de i.a. + 0,5 g ha-1), cinetina (0,5 g ha-1), corte manual das gemas apicais e controle. Na subparcela, foram utilizadas seis cultivares de soja (M 6410 IPRO, M 5917 IPRO, NS 7670 RR, NS 6909 IPRO, BMX Lança IPRO e Produza IPRO). Em campo, foram avaliados o índice de acamamento, altura de plantas, número de nós e ramos, vagens e grãos por planta, massa de 100 grãos e produtividade. Em casa-de-vegetação, foram quantificados o amido, açúcares redutores, sacarose e açúcares totais nas folhas, caules e raízes de três cultivares de soja. A aplicação de lactofen em V6 influenciou nas características morfoagronômicas das cultivares no campo e incrementou a produtividade em 312 kg ha-1 de soja, considerando-se todas as cultivares. O fito-hormônio não influenciou nas características morfoagronômicas e produtividade. Os tratamentos não induziram alteração na partição de carboidratos destinados às raízes.

ABSTRACT The herbicide lactofen has been used by producers in many conditions, in order to increase the soybean yield. This study aimed to evaluate the influence of lactofen and the phytohormone kinetin on the morpho-agronomic traits, carbohydrate partitioning and yield, in soybean cultivars. Three experiments were carried out in the field, in addition to one experiment in a greenhouse. A randomized block design, with four replications, was used. The treatments were: lactofen [144 g ha-1 of active ingredient (a.i.)], lactofen + kinetin (144 g ha-1 of a.i. + 0.5 g ha-1), kinetin (0.5 g ha-1), manual cutting of apical buds and control. In the subplots, six soybean cultivars (M 6410 IPRO, M 5917 IPRO, NS 7670 RR, NS 6909 IPRO, BMX Lança IPRO and Produza IPRO) were used. In the field, the plant lodging index, plant height, number of nodes and branches, pods and grains per plant, mass of 100 grains and grain yield were evaluated. In the greenhouse, the starch, reducing sugars, sucrose and total sugars in the leaves, stems and roots of three soybean cultivars were quantified. The application of lactofen in the V6 stage influenced the morpho-agronomic traits of the cultivars in the field and increased the soybean yield by 312 kg ha-1, considering all the cultivars. The phytohormone did not influence the morpho-agronomic traits neither the grain yield. The treatments did not induce modification in the partitioning of carbohydrates destined to the roots.

O objetivo deste trabalho foi avaliar as respostas fotossintéticas da cana‑de‑açúcar aos efeitos simultâneos e isolados de baixa temperatura noturna (TN) e deficiência hídrica (DH). Após 128 dias do plantio, as plantas da cultivar IACSP94-2094 foram submetidas aos tratamentos: controle, sem DH e com TN de 20°C (TN20); com DH e TN de 20°C (DH/TN20); sem DH e com TN de 12°C (TN12); e com DH e TN de 12°C (DH/TN12) por cinco dias. Após o período de tratamento, as plantas foram irrigadas e submetidas à TN de 20°C por mais quatro dias, para recuperação. Houve decréscimos na assimilação de CO2 em todos os tratamentos. A recuperação total da assimilação de CO2 foi observada apenas nas plantas do tratamento TN12. A ocorrência simultânea da baixa temperatura noturna e da deficiência hídrica causou dano acentuado e persistente na condutância estomática, na capacidade máxima da ribulose‑1,5‑bisfosfato carboxilase, no transporte aparente de elétrons, no fator de eficiência e na eficiência operacional do fotossistema II, o que resultou em limitações difusivas, bioquímicas e fotoquímicas da fotossíntese das plantas de cana‑de‑açúcar.

The objective of this work was to evaluate the photosynthetic responses of sugarcane to the simultaneous and isolated effects of low night temperature (TN) and water deficit (DH). After 128 days of planting, plants of the cultivar IACSP94-2094 were subjected to the following treatments: control, without DH and with TN of 20°C (TN20); with DH and TN of 20°C (DH/TN20); without DH and with TN of 12°C (TN12); and with DH and TN of 12°C (DH/TN12). After the period of treatment, plants were irrigated and subjected to TN of 20°C for four more days, for recovery. There were decreases in CO2 assimilation in all treatments. Total recovery of CO2 assimilation was observed only in plants from the treatment TN12. The simultaneous occurrence of low night temperature and water deficit caused a accentuated and persistent effect on stomatal conductance, on the maximum capacity of ribulose‑1,5‑bisphosphate carboxylase, on the electron transport rate, on the efficiency factor, and on the operational efficiency of photosystem II, which resulted in diffusive, biochemical, and photochemical limitations of photosynthesis of sugarcane plants.

The non-invasive, magnetic leaf patch clamp pressure probe (also termed ZIM-probe) allows for the first time to measure continuously turgor pressure changes of plant leaves over long periods of time with high precision and in real time. The probe has become an important tool in plant physiology, molecular biology and ecology, but also in agriculture because the probe is very robust and user-friendly. Growers receive the information about the water status of their plants by wireless telemetry, mobile network and internet on an as-needed basis and can thus adjust very precisely both the timing of irrigation and the quantity of water to apply. Effects of air and leaf temperature, relative humidity, illumination and wind on turgor pressure can be monitored very sensitively both under indoor and outdoor conditions. Even the effects of blue and red light as well as of oscillations of stomata aperture on turgor pressure can be monitored by the probe with high sensitivity. Similarly, water deficit due to increase of the osmotic pressure in the nutrition solutions resulted in significant changes of the probe signals. Multiple probe readings open up new possibilities to resolve (together with other techniques) the mechanisms of short- and long-distance water transport, particularly how plants can cope with water shortage. The applications of the magnetic probe are numerous and one can expect highly interesting developments in plant water relations in the nearest future.

O objetivo deste trabalho foi avaliar de que maneira a alta disponibilidade de fósforo no solo afeta a fotossíntese e o crescimento de mudas de cafeeiro arábica (Coffea arabica). Mudas da cultivar Ouro Verde com aproximadamente quatro meses de idade, cultivadas com boa disponibilidade hídrica, foram submetidas a três tratamentos quanto à disponibilidade de fósforo: quantidade recomendada de P, na literatura (PA); duas vezes a dosagem utilizada em PA (P+); e sem adição de P ao solo (P-). Após 70 dias da aplicação dos tratamentos, foram avaliados: as trocas gasosas, a atividade fotoquímica, o potencial de água da folha, a condutância hidráulica da planta (K L), a partição de matéria seca na planta, os teores de pigmentos e carboidratos, e a composição química das folhas. O tratamento P- influenciou negativamente a fotossíntese, e levou à restrição do crescimento das plantas. As plantas do tratamento P+ apresentaram maior teor foliar de P (~1,9 g kg-1), com incrementos na assimilação de CO2, na eficiência instantânea de carboxilação e na atividade fotoquímica - maior eficiência do fotossistema II e maior transporte aparente de elétrons - em relação às plantas do tratamento PA. Houve aumento em K L, maior teor de carboidratos foliares e maior teor de clorofila nas plantas que receberam o dobro da dose recomendada de P, as quais apresentaram maior produção de matéria seca em relação às de PA e P-.

The objective of this work was to evaluate how high soil phosphorus (P) availability affects the photosynthesis and growth of young coffee arabica plants (Coffea arabica). Four months old coffee seedlings of the Ouro Verde cultivar, cultivated in good hydric conditions, were exposed to three P availability treatments: P dosage recommended in the literature (RP); two times the recommended dosage (P+); and without P (P-). Seventy days after treatment application, evaluations of leaf gas exchange, photochemical activity, leaf water potential, plant hydraulic conductance (K L), dry matter partitioning, leaf contents of pigments and carbohydrates, and leaf chemical composition were done. The treatment without P caused reduction in photosynthesis, leading to lower plant growth. The plants of the P+ treatment showed the highest leaf P concentrations (~1.9 g kg-1), with increasing leaf CO2 assimilation and instantaneous carboxylation efficiency, and higher photochemical activity - higher effective quantum efficiency of photosystem II and apparent electron transport rate - when compared to plants exposed to RP treatment. Plants exposed to the double P recommended dosage exhibited higher K L, higher leaf carbohydrate content and higher chlorophyll content, resulting in higher dry matter production as compared to RP and P-.

O objetivo deste trabalho foi avaliar as respostas biométricas e fisiológicas de cana-de-açúcar (Saccharum spp.) ao deficit hídrico (DH), em diferentes fases fenológicas. Os genótipos IACSP 94-2094 e IACSP 96-2042 foram submetidos a DH nas fases de crescimento inicial, crescimento máximo e de acúmulo de sacarose no colmo. O delineamento experimental foi inteiramente casualizado. A suscetibilidade ao DH foi determinada pela redução de matéria seca do colmo e do conteúdo de sólidos solúveis no caldo. O deficit hídrico causou redução nas trocas gasosas, nas três fases fenológicas, em ambos os genótipos. Foi observada menor altura das plantas, menor acúmulo de matéria seca do colmo e de sólidos solúveis, e redução no número e comprimento de entrenós, apenas na fase de crescimento inicial, no clone IACSP 96-2042. Na fase de crescimento inicial, observou-se tolerância ao DH no genótipo IACSP 94-2094, com evidências de aclimatação fisiológica, e redução na produção de fitomassa e de sólidos solúveis no genótipo IACSP 96-2042, como resposta à menor condutância estomática e à menor eficiência aparente de carboxilação da fotossíntese. Independentemente da fase fenológica, o genótipo IACSP 94-2094 foi tolerante ao deficit hídrico, pois manteve a produção de fitomassa mesmo com redução das trocas gasosas.

The aim of this work was to evaluate the biometric and physiological responses of sugarcane (Saccharum spp.) to water deficit (WD), during different phenological phases. Genotypes IACSP 94-2094 and IACSP 96-2042 were subjected to WD conditions during the initial, maximum and sucrose accumulation phases. The experiment was carried out in a completely randomized design. Susceptibility to WD was established by reduction in stalk dry matter and soluble solids. Water deficit reduced leaf gas exchange in all phenological phases of both genotypes. Lower plant height, less stalk dry matter and soluble solids, and reduction in number and length of internodes were only observed during the initial growth phase of the IACSP 96-2042 clone. In the initial growth phase, tolerance to WD was observed for IACSP 94-2094, with evidence of physiological acclimation, and for IACSP 96-2042 in reduction phytomass production and its soluble solid content, caused by lower stomatal conductance and lower apparent carboxylation efficiency which limit photosynthesis. Regardless of the phenological phase, genotype IACSP 94-2094 was tolerant to WD, since its phytomass production was maintained even with impairment of leaf gas exchange.