New perspectives from soybean thanks to CREA research
Next thursday, on 2 September 2021, CREA Animal Production and Aquaculture Research Centre has organised the event Primary metabolism and leaf senescence in soybean under heat and water stress during filling: relationship with yield and grain protein.
Type of event: Convegno
When: Thursday 02 September 2021 - hour: 14:30
Where: Animal Production and Aquaculture - Viale Piacenza, 29 Lodi
Soybean [Glycine max (L.) Merr.] represents an important source of nutrition due to its levels of protein of high biological value, which could contribute considerably to the global food and protein demand required by 2050. The crop generally grows exposed to episodes of high temperatures and/or insufficient water availability. Both factors affect grain yield and quality, and are exacerbated in the actual context of climate change.
The aim of the thesis was to analyze in genotypes contrasting in grain protein concentration, the ecophysiological and biochemical-physiological responses associated with photoassimilates generation and remobilization determining yield and grain protein content (GPr) in field soybean exposed to episodes of heat stress (HS), water stress (WS) and their interaction (HS×WS) during grain filling (GF). The hypothesis was that the high protein genotype anticipates foliar senescence, exhibiting a greater assimilates remobilization capacity and differential effects on these processes under HS and/or WS conditions.
Scientific abstract
Two experiments were conducted at INTA Manfredi using two contrasting non-transgenic genotypes in terms of grain protein concentration: i) high protein (HP; 42%) and ii) low protein (LP; 37%). The experimental design was split-split plot with two replications, resulting in four treatments: control (without HS and WS), HS (episodes with temperatures > 32 ºC, 6 h day-1, 15 days from the start of GF), WS (25% of available soil water content throughout the GF) and HS×WS. Episodes of HS without WS, regardless of genotype, had not significantly affected yield, its components and GPr. Neither were the generation and remobilization of assimilates negatively affected, suggesting that HS episodes could activate acclimation processes at the photosynthetic level associated with foliar cooling mechanisms and antioxidant protection. The WS, regardless of genotype and HS, reduced yield (25-57%), grain number (39-21%), grain weight (39-13%) and GPr (14-45%), which were of different magnitudes according to the stress characteristics generated in each experiment. Under WS, photosynthesis was reduced up to 50% as a result of stomatal responses (foliar transpiration, internal carbon dioxide, stomatal conductance, canopy temperature) and nonstomatal responses (parameters obtained from chlorophyll fluorescence), and oxidative stress was increased (significant increases in membrane permeability and decreases of the antioxidant capacity). In addition, it caused early foliar senescence (evidenced by significant reductions in the SPAD values and a reduction of GF duration), reduced the C and N remobilization from stems, affecting the partition of assimilates to grains. The GPr content was associated to a multiplicity of factors such as the source-sink ratio, assimilates remobilization from stems, partitioning to grains, N available at the beginning of GF and duration of GF, factors on which HP showed higher performance in relation to LP.
To our knowledge, these physiological processes related to photosynthesis, remobilization of assimilates and foliar senescence have not been investigated by comparing soybean genotypes with different grain protein concentrations exposed to HS and WS interaction during GF. In addition, studies addressing these aspects by combining scales and sub disciplines, integrating both ecophysiological and biochemical-physiological variables are less common. The knowledge generated can be applied to breeding programs, to crop management strategies design, and to technologies associated with the use of remote sensors.