RESUMOObjetivou-se neste trabalho avaliar o comportamento fisiológico de diferentes genótipos de tomateiro, a fim de contribuir com a seleção de plantas com tolerância ao estresse hídrico. Utilizou-se o delineamento casualizado em blocos, com três blocos e dez tratamentos, sendo: oito genótipos F 2 RC 1 [UFU80-F 2 RC 1 #1 (3.5); UFU102-F 2 RC 1 #7 (13.4); UFU102-F 2 RC 1 #7 (13.3); UFU102-F 2 RC 1 #7 (16.8); UFU102-F 2 RC 1 #3 (2.7); UFU80-F 2 RC 1 #1 (11.8); UFU102-F 2 RC 1 #7 (16.7); UFU102-F 2 RC 1 #3 (14.5) ], e outros dois genótipos utilizados como testemunhas UFU-650 e LA-716. O experimento foi conduzido em ambiente protegido com monitoramento da densidade de fluxo (W m -2 ), radiação solar global (Qg), temperatura do ar (ºC), umidade relativa do ar (%) e o potencial mátrico no substrato (kPa). As características fisiológicas coletadas foram: temperatura foliar (T leaf ), CO 2 interno (Ci), transpiração (E), condutância estomática (gs) e assimilação de CO 2 (A), determinadas pelo analisador portátil de gás no infravermelho -IRGA. Pode-se observar que o acesso selvagem S. pennellii foi 6,96 vezes inferior em relação ao genitor recorrente UFU-650 (linhagem pré-comercial, susceptível ao déficit hídrico). A condutância estomática (gs) apresentou valores significativos entre os genótipos. Os resultados obtidos contribuem para caracterização fisiológica do acesso Solanum pennellii (tolerante a seca) e podem auxiliar na seleção de plantas F 2 RC 1 resistentes ao déficit hídrico. Palavras-chave: déficit hídrico, estresse abiótico, Solanum lycopersicum Selection of tomato genotypes under water stress due to the expression of physiological characteristics ABSTRACTThe objective of this study was to evaluate the physiological behavior of different tomato genotypes to assist in the selection of plants with tolerance to drought stress. It was used three blocks random and ten treatments: eight genotypes F 2 RC 1 [UFU80-F 2 RC 1 #1 (3.5); UFU102-F 2 RC 1 #7 (13.4); UFU102-F 2 RC 1 #7 (13.3); UFU102-F 2 RC 1 #7 (16.8); UFU102-F 2 RC 1 #3 (2.7); UFU80-F 2 RC 1 #1 (11.8); UFU102-F 2 RC 1 #7 (16.7); UFU102-F 2 RC 1 #3 (14.5)], UFU-650 and LA-716. The experiment was conducted in a greenhouse with monitoring the flux density (W m -2 ), solar radiation (Qg), air temperature (°C), relative humidity (%) and the matric potential in the substrate (kPa). The collected physiological characteristics were: leaf temperature (Tleaf), internal CO 2 (Ci), transpiration (E), stomatal conductance (gs) and CO 2 assimilation (A), determined by portable gas analyzer infrared -IRGA. It was observed that the wild tomato S. pennellii was 6.96 times lower than the recurrent parent UFU-650 (pre-commercial line, susceptible to drought). The stomatal conductance (gs) showed significant values among genotypes. The results contribute to physiological characterization access S. pennellii (drought tolerant) and can assist in the selection of F 2 RC 1 plants resistant to drought.
This study aimed to quantify water deficit levels that compromise sugarcane initial growth exposed to different availability soil depths. The experiment was conducted in a greenhouse by using 100-liter capacity asbestos-cement boxes filled with different soil layers simulating depths of 10, 20, 30, and 40 cm. Water deficit levels were represented by accumulated reference evapotranspiration of 0, 40, 80, 120, 160, 200, 240, and 280 mm, which was considered from planting to irrigation return. Soil moisture at field capacity at planting time was sufficient to promote sprouting and emergence regardless the water deficit level that was subsequently exposed. For soil depths of 10 and 20 cm, a 160-mm water deficit level caused total plant death. On the other hand, for soil depths of 30 and 40 cm, a 200-mm water deficit level promoted plant death. A water deficit level from 40 mm significantly reduced plant growth regardless soil depth.
Water stress can affect the yield in tomato crops and, despite this, there are few types of research aiming to select tomato genotypes resistant to the water stress using physiological parameters. This experiment aimed to study the variables that are related to the gas exchanges and the efficiency in water use, in the selection of tomato genotypes tolerant to water stress. It was done in a greenhouse, measuring 7 x 21 m, in a randomized complete block design, with four replications (blocks), being five genotypes in the FBC generation, which were previously obtained from an interspecific cross between Solanum pennellii versus S. lycopersicum and three check treatments, two susceptible [UFU-22 (pre-commercial line) and cultivar Santa Clara] and one resistant (S. pennellii). At the beginning of flowering, the plants were submitted to a water stress condition, through irrigation suspension. After that CO assimilation, internal CO, stomatal conductance, transpiration, leaf temperature, instantaneous water use efficiency, intrinsic efficiency of water use, instantaneous carboxylation efficiency, chlorophyll a and b, and the potential leaf water (Ψf) were observed. Almost all variables that were analyzed, except CO assimilation and instantaneous carboxylation efficiency, demonstrated the superiority of the wild accession, S. pennellii, concerning the susceptible check treatments. The high photosynthetic rate and the low stomatal conductance and transpiration, presented by the UFU22/FBC#2 population, allowed a better water use efficiency. Because of that, these physiological characteristics are promising in the selection of tomato genotypes tolerant to water stress.
The leaf area index (LAI) is relevant in studies of phenomena at different scales, such as for the leaf to canopy scale and the calculation of the extinction coefficient of photosynthetically active radiation (kPAR), providing input for the parameterization of physiological basis models. The objective of this work was to verify the variation of the LAI and the coffee kPAR subjected to different drip irrigation levels (130, 100, 70, and 40%) and to compare the data obtained from radiation bar linear sensors (SunScan) in the plants that received full irrigation with the values found by other LAI estimation methodologies. The study was conducted in Piracicaba, São Paulo State, Brazil, using the species Coffea arabica cv. Red Catuaí IAC 144; a drip irrigation system was adopted, with the irrigation controlled by tensiometry. The mean LAI values were higher in the L130 (irrigation level of 130%) and L100 (irrigation level of 100%) treatments than those with deficit irrigation depths. The mean kPAR values were lower for the L130 and L100 treatments than the values found in the deficit irrigation depth treatments. When comparing SunScan to other methodologies, the mean error (ME) and absolute mean error (AME) were high.
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