Gas exchanges and water use efficiency in the selection of tomato genotypes tolerant to water stress

Abstract

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.

Respostas fisiológicas do girassol em fase reprodutiva ao estresse hídrico e salino

“…Em oposição as plantas irrigadas com água sem adição de sal (0,6 dS m -1 ) a Gs obteve sempre valores iguais ou superiores ao das plantas irrigadas com água salina, entretanto a fotossíntese não obteve o mesmo comportamento, sendo inferior nos maiores NI (75% e 100%), o que explica justamente as maiores Ci, já que o CO2 que se difundiu sem nenhuma restrição para o interior da folha não foi fixado pelo processo fotossintético na mesma proporção observada nas plantas irrigadas com água salina, provavelmente devido a uma diminuição na atividade de enzimas envolvidas no processo de fixação de CO2 (Borba et al, 2017).…”

Multi-Environment Yield Components in Advanced Common Bean (Phaseolus vulgaris L.) × Tepary Bean (P. acutifolius A. Gray) Interspecific Lines for Heat and Drought Tolerance

“…These measures were gathered using the LI-6800 portable photosynthesis system from 8:00-11:00 am. Additional compound parameters were computed as follows, ( 8) iWUE: instantaneous water use efficiency was measured as the relation A/E, (9) inWUE: intrinsic efficiency of water use computed as the relation A/gs, and (10) iCE: instantaneous carboxylation efficiency was measured as the relation A/Ci [21]. Measurements were made on three plants per genotype on a fully expanded leaf from the upper third part of the plant.…”

Morphological and physiological responses of Calobota sericea plants subjected to water limitation and subsequent rewatering

“…The measurements obtained were thereafter adjusted for each leaf area measured. From the default measurements, photosynthetic water use efficiency (A/E) for each plant was calculated (Borba et al 2017). Thereafter, all plant material was collected and separated into roots, stems and leaves and the fresh mass (g) and root length (cm) determined.…”