Phosphorus Nutrition Affects Temperature Response of Soybean Growth and Canopy Photosynthesis

In nature, crops such as soybean are concurrently exposed to temperature (T) stress and phosphorus (P) deficiency. However, there is a lack of reports regarding soybean response to T × P interaction. To fill in this knowledge-gap, soybean was grown at four daily mean T of 22, 26, 30, and 34°C (moderately low, optimum, moderately high, and high temperature, respectively) each under sufficient (0.5 mM) and deficient (0.08 mM) P nutrition for the entire season. Phosphorus deficiency exacerbated the low temperature stress, with further restrictions on growth and net photosynthesis. For P deficient soybean at above optimum temperature (OT) regimes, growth, and photosynthesis was maintained at levels close to those of P sufficient plants, despite a lower tissue P concentration. P deficiency consistently decreased plant tissue P concentration ≈55% across temperatures while increasing intrinsic P utilization efficiency of canopy photosynthesis up to 147%, indicating a better utilization of tissue P. Warmer than OTs delayed the time to anthesis by 8–14 days and pod development similarly across P levels. However, biomass partitioning to pods was greater under P deficiency. There were significant T × P interactions for traits such as plant growth rates, total leaf area, biomass partitioning, and dry matter production, which resulted a distinct T response of soybean growth between sufficient and deficient P nutrition. Under sufficient P level, both lower and higher than optimum T tended to decrease total dry matter production and canopy photosynthesis. However, under P-deficient condition, this decrease was primarily observed at the low T. Thus, warmer than optimum T of this study appeared to compensate for decreases in soybean canopy photosynthesis and dry matter accumulation resulting from P deficiency. However, warmer than OT appeared to adversely affect reproductive structures, such as pod development, across P fertilization. This occurred despite adaptations, especially the increased P utilization efficiency and biomass partitioning to pods, shown by soybean under P deficiency

Combined effects of phosphorus nutrition and elevated carbon dioxide concentration on chlorophyll fluorescence, photosynthesis, and nutrient efficiency of cotton

To examine the combined effects of phosphorus (P) nutrition and CO2 on photosynthesis, chlorophyll fluorescence (CF), and nutrient utilization and uptake, two controlled-environment experiments were conducted using 0.01, 0.05 and 0.20 mM external phosphate each at ambient and elevated CO2 (aCO2: 400 and eCO2: 800 mmol mol–1, respectively). The CF parameters were affected more by P nutrition than by CO2 treatment. Photoinhibition of photosystem II (PSII) was due to increased minimal CF (Fo\u27) and decreased maximal CF (Fm\u27), and efficiency of energy harvesting (Fv\u27/Fm\u27). In addition, reduced electron transport rate (ETR), the quantum yield of PSII (FPSII) and CO2 assimilation (FCO2 ), and overall photochemical quenching in the P-deficient leaves led to reduction in the efficiency of energy transfer to the PSII reaction center. Stimulation in the FPSII/FCO2 and photorespiration (ETR/Pnet) was found under P deficiency, whereas the opposite was the case under CO2 enrichment. On average, photosynthetic rate (Pnet) and stomatal conductance declined by 50–53% at 0.05 mM P and by 70–72% at 0.01 mM P as compared to the 0.20 mM P treatment. However, P deficiency, especially at eCO2, tended to increase the intrinsic water-use efficiency. In the P-deficient plants, the decline in the P and N utilization efficiency (up to 91%) of biomass production was mainly associated with greater reduction in the biomass relative to the tissue P concentration as the P supply was reduced. However, it was significantly stimulated by eCO2 especially at higher P supply. The CO2 · P interaction was observed for some parameters such as Fo\u27, Fm\u27, P utilization efficiencies of photosynthesis and biomass production that might be attributed to the irresponsiveness of these parameters to eCO2 under low P treatment. Thus, P deficiency limited the beneficial effect of eCO2. A close relationship between total biomass and photosynthesis with the P and N utilization or uptake efficiencies was found. The P utilization efficiency of Pnet appeared to be stable across a range of leaf P concentrations, whereas the N-utilization efficiency markedly increased with leaf P and differed between CO2 levels. An apparent effect of both the treatments (P and CO2) on N-uptake and utilization efficiency also indicated the alteration in N acquisition and assimilation in cotton plants

Potassium Starvation Limits Soybean Growth More than the Photosynthetic Processes across CO2 Levels

Elevated carbon dioxide (eCO2) often enhances plant photosynthesis, growth, and productivity. However, under nutrient-limited conditions the beneficial effects of high CO2 are often diminished. To evaluate the combined effects of potassium (K) deficiency and eCO2 on soybean photosynthesis, growth, biomass partitioning, and yields, plants were grown under controlled environment conditions with an adequate (control, 5.0 mM) and two deficient (0.50 and 0.02 mM) levels of K under ambient CO2 (aCO2; 400 μmol mol−1) and eCO2 (800 μmol mol−1). Results showed that K deficiency limited soybean growth traits more than photosynthetic processes. An ~54% reduction in leaf K concentration under 0.5 mM K vs. the control caused about 45% less leaf area, biomass, and yield without decreasing photosynthetic rate (Pnet). In fact, the steady photochemical quenching, efficiency, and quantum yield of photosystem II, chlorophyll concentration (TChl), and stomatal conductance under 0.5 mM K supported the stable Pnet. Biomass decline was primarily attributed to the reduced plant size and leaf area, and decreased pod numbers and seed yield in K-deficient plants. Under severe K deficiency (0.02 mM K), photosynthetic processes declined concomitantly with growth and productivity. Increased specific leaf weight, biomass partitioning to the leaves, decreased photochemical quenching and TChl, and smaller plant size to reduce the nutrient demands appeared to be the means by which plants adjusted to the severe K starvation. Increased K utilization efficiency indicated the ability of K-deficient plants to better utilize the tissue-available K for biomass accumulation, except under severe K starvation. The enhancement of soybean growth by eCO2 was dependent on the levels of K, leading to a K × CO2 interaction for traits such as leaf area, biomass, and yield. A lack of eCO2-mediated growth and photosynthesis stimulation under severe K deficiency underscored the importance of optimum K fertilization for maximum crop productivity under eCO2. Thus, eCO2 compensated, at least partially, for the reduced soybean growth and seed yield under 0.5 mM K supply, but severe K deficiency completely suppressed the eCO2-enhanced seed yield

Combined effects of drought and CO2 enrichment on foliar metabolites of potato (Solanum tuberosum L.) cultivars

Drought invokes a variety of metabolic alterations in plant leaves to cope with stress situations. To understand the effects of CO2 and drought stress for leaf metabolic changes in potato [Solanum tuberosum (L)], two contrasting potato cultivars Harley Blackwell (HB, an early maturing, newer cultivar) and Snowden (SD, an established, full-season cultivar) were tested under water-limited conditions and CO2 enrichment. The results revealed that most of the drought-triggered metabolites were lower in HB compared to SD. However, HB showed quicker adjustments in the metabolic processes such as conversion of starch into soluble sugars and biosynthesis of phenylalanine and other compatible solutes at the early stages of the drought progression. Moreover, the existence of genotypic differences for leaf water potential (LWP) in response to CO2 enrichment was evident. Our study provides insights into the possible metabolic strategies of drought tolerance in potato cultivars under ambient and elevated CO2

An epidemiological investigation of insomnia: A survey

Sleep is commonly defined as a state in which physical activities and sensory perception are greatly reduced, and it is frequently associated with our body's recuperative period. However, research has shown that sleep is also required for other vital processes such as memory consolidation and normal physiological functioning. Extensive research has shown that the areas that control our sleeping behaviour are the hypothalamus, brain stem, midbrain, and amygdala. These areas coordinate events during the non-REM and REM phases of sleep-wake cycles. GABA and adenosine, two chemical neurotransmitters, are also involved and play an important role in our sleep cycle. Insomnia has caused a slew of psychological and physiological issues such as fatigue, decreased mental concentration, irritable nature and a higher risk of heart attacks and stroke. It has reduced the patient's quality of life of the patient and have a social impact on them. Primary insomnia is defined as the inability/absence of proper sleep and impaired daily life functioning. Secondary insomnia, on the other hand, is believed to result from pre-existing medical conditions, substance abuse, or as a side effect of certain drug therapy. Insomnia is diagnosed through physical examination and the use of electrical devices to monitor sleep behavior.&nbsp

Parental Environmental Effects on Seed Quality and Germination Response to Temperature of Andropogon gerardii

Parental environments (PEs) affect seed quality and might alter the re-establishment of big bluestem grass due to impacts on seed germination. An in vitro study was conducted to quantify the temperature response of seed germination and its interaction with the PE in big bluestem. Seeds developed under eight PEs consisting of a combination of four day/night growth temperatures (GTs) (20/12, 25/17, 30/22, and 35/27 °C) and two CO2 levels (360 and 720 µL L−1) were germinated at eight temperatures (germination temperatures (GRTs)) ranging from 10 to 42.5 °C. Quadratic and modified bilinear regressions best described the cardinal temperatures for the estimated maximum seed germination (MSG) and seed germination rate (SGR), respectively. The average MSG and SGR showed differential responses to the PEs and significantly declined above a 35 °C GRT across the PEs. For the SGR, the minimum and optimum temperatures showed significant differences from other treatments but the opposite response to elevated CO2, while maximum temperatures significantly declined at high (35/27 °C) and low GTs (20/12 °C). Seed quality parameters, individual seed weight, and C and N contents showed a high correlation (R2 > 60) with the average percentage of seed germination and the SGR. Thus, high temperatures for both the PEs (>30/22 °C) and GRTs (>30 °C) could significantly reduce germination, affecting the re-establishment of big bluestem

Proteomics, physiological, and biochemical analysis of cross tolerance mechanisms in response to heat and water stresses in soybean.

Water stress (WS) and heat stress (HS) have a negative effect on soybean plant growth and crop productivity. Changes in the physiological characteristics, proteome, and specific metabolites investigated on molecular and cellular functions were studied in two soybean cultivars exposed to different heat and water stress conditions independently and in combination. Leaf protein composition was studied using 2-DE and complemented with MALDI TOF mass spectrometry. While the two cultivars displayed genetic variation in response to water and heat stress, thirty-nine proteins were significantly altered in their relative abundance in response to WS, HS and combined WS+HS in both cultivars. A majority of these proteins were involved in metabolism, response to heat and photosynthesis showing significant cross-tolerance mechanisms. This study revealed that MED37C, a probable mediator of RNA polymerase transcription II protein, has potential interacting partners in Arabidopsis and signified the marked impact of this on the PI-471938 cultivar. Elevated activities in antioxidant enzymes indicate that the PI-471938 cultivar can restore the oxidation levels and sustain the plant during the stress. The discovery of this plant's development of cross-stress tolerance could be used as a guide to foster ongoing genetic modifications in stress tolerance