A test of rapid leaf photosynthesis-intercellular CO2 concentration response (RACiR) technique for evergreens and herbs

Using traditional photosynthesis-intercellular CO concentration (A-C) response (TACiR) curves to obtain the maximum rates of ribulose-1,5-bisphosphate carboxylase oxygenase carboxylation (V) and electron transport (J) is time-consuming and labor-intensive. Instead, the rapid A-C response (RACiR) technique provides a potential way with high efficiency. However, multiple parameter settings of RACiR technique for different plant life forms remain unclear. Here, we used Li-Cor 6800 to test the applicability and optimum parameter settings of RACiR curves for evergreens and herbs. We set 11 groups of [CO], i.e., R1 (400-1500 ppm), R2 (400-200-800 ppm), R3 (420-20-620 ppm), R4 (420-20-820 ppm), R5 (420-20-1020 ppm), R6 (420-20-1220 ppm), R7 (420-20-1520 ppm), R8 (420-20-1820 ppm), R9 (450-50-650 ppm), R10 (650-50 ppm) and R11 (650-50-650 ppm), and made contrasts between TACiR and RACiR curves. We found that V and J calculated by TACiR and RACiR overall showed no significant differences across 11 [CO] gradients (P<0.05). The efficiency and accuracy of R2, R3, R4, R9 and R10 showed higher superiority than others. Moreover, the accuracy of manual empty chamber correction method was higher than the automatic method. In conclusion, the RACiR technique could be generally used to obtain photosynthetic parameters with higher efficiency than traditional methods for various life forms.

Physiological, Biochemical, and Biometrical Response of Cultivated Strawberry and Wild Strawberry in Greenhouse Gutter Cultivation in the Autumn-Winter Season in Poland—Preliminary Study

Strawberry and wild strawberry are among the most popular horticultural crops. Due to the development of soilless cultivation systems, the whole-year production of these economically important fruit crops is achievable even in countries with temperate climate. However, the responses of strawberry (Fragaria × ananassa Duch.) and wild strawberry (Fragaria vesca L.) to microclimate conditions in greenhouse gutter cultivation in the autumn–winter season in Poland have not been yet determined. The aim of this study was to analyze the physiological, biochemical, and biometrical responses of two cultivars of strawberry ‘Ostara’ and ‘San Andreas’ and two cultivars of wild strawberry ‘Baron von Solemacher’ and ‘Regina’ grown for 20 weeks, starting from September 17th, in controlled greenhouse conditions on coconut mats in gutters in the autumn–winter season and irradiated with sodium lamps. Strawberry ‘San Andreas’ produced 30% larger leaves and almost three-fold higher fresh and dry weight of biomass than ‘Ostara’. The strawberry plants ‘San Andreas’ had a higher content (20%) of chlorophyll a and 30% of chlorophyll b than ‘Ostara’ plants. Generally, ‘San Andreas’ displayed an overall higher concentration of intercellular CO2 (about 14%) than ‘Ostara’ plants providing higher gas exchange processes. Photosynthetic rate amounted to 13.0 μmol·m−2·s−1 for ‘San Andreas’ that was almost two-fold higher than for ‘Ostara’. ‘San Andreas’ flower and fruit productions were uniform and the six-fold higher individual fruit yield proved the excellent attributes of this cultivar to the greenhouse cultivation. Even though the productivity of the two studied wild strawberry cultivars was similar, ‘Regina’ showed higher values of some parameters than ‘Baron von Solemacher’ (40% larger leaves, 25% higher photosynthetic rate, 10% higher concentration of intercellular CO2). A high nutritional value of fruits is maintained compared to traditional open-air cultivation.

The Influence of Soil Tillage System on Changes in Gas Exchange Parameters of Pisum sativum L.

A field experiment was carried out in 2017–2019 as a split-plot design with four replicates at the Agricultural Experimental Station in Grabów, Poland. The aim of the study was to compare the gas exchange parameters of the pea depending on the use of different soil tillage systems. Physiological plant parameters as: net photosynthetic rate (PN), transpiration rate (E), stomatal conductance (gs), intercellular CO2 concentration (Ci) and relative chlorophyll content were measured in three developmental stages. The study have showed that all the measured parameters were affected by the tillage system of the soil. Net photosynthetic rate and transpiration rate were significantly lower in the treatments, where simplified-tillage was applied. Pea grown in the plough tillage (CT) showed a generally higher rate of net photosynthesis and transpiration rate compared to that of peas grown in the reduced tillage and no-tillage systems, but this was dependent on the plant development stage and the weather conditions prevailing in a given year. The highest intercellular CO2 concentration (Ci) under different cultivation methods were found in the no-tillage system, regardless of the developmental stage of legumes. The values of determination coefficients showed a positive relationship between the photosynthetic rate and seed yield of the peas tested in all the years of the research. The study also showed that a significantly higher SPAD index was found in the CT tillage system, irrespectively on the developmental stage.

The Effects of Various Doses and Types of Effective Microorganism Applications on Microbial and Enzyme Activity of Medium and the Photosynthetic Activity of Scarlet Sage

The aim of this study was to examine the influence of various types and levels of effective microorganism (EM) applications on scarlet sage. For this purpose, EMs were applied at the following three concentrations: 1:10, 1:50, and 1:100. Moreover, two types of treatments (spraying and watering) and a combination of the two were also examined. Photosynthetic intensity was analyzed, including the net photosynthesis rate (PN), stomatal conductance (gS), and intercellular CO2 concentration (Ci). Additionally, chlorophyll a, b, and a + b, and the chlorophyll b/a ratio were analyzed. The microbial content in the medium and soil enzyme activity were also evaluated to examine the effect of EMs on soil biological properties. The investigations revealed a high positive effect of EMs on the photosynthetic activity of most EM combinations compared with the control. The greatest positive effect was noted for the highest EM concentration application for both types of treatments. There was no such influence on soil activity. An increase was noted only in the number of fungi and dehydrogenase activity, while the rest of the soil biological status parameters revealed significant variability, and mostly small or no effects were recorded.

Physiological response of Solanum nigrum to salt stress

The effects of salt stress (100, 200, 300 mmol/L) on physiological characteristics of Solanum nigrum seedlings were studied by pot experiment. The results showed that the contents of chlorophyll a, chlorophyll b, carotenoids and total chlorophyll in S. nigrum leaves showed a trend of first flattening and then increasing with the aggravation of salt stress. With the aggravation of salt stress, the net photosynthetic rate, stomatal conductance and intercellular CO2 concentration of S. nigrum decreased gradually, and reached the lowest value when the NaCl concentration was 300 mmol/L. With the increase of NaCl concentration, the SOD activity of S. nigrum leaves decreased gradually. When the concentration of NaCl was 300 mmol/L, the SOD activity of S. nigrum decreased by 53.39% (P < 0.05). The activities of POD, CAT and soluble protein in S. nigrum increased first and then decreased with the increase of NaCl concentration. When the concentration of NaCl was 100 mmol/L, the activities of POD, CAT and the content of soluble protein reached the maximum.

Effects of Nutrient Solution Irrigation Quantity and Downy Mildew Infection on Growth and Physiological Traits of Greenhouse Cucumber

Abiotic and biotic stresses both decrease the quality and quantity of cultivated plants. In this study, in order to see the responses of cucumber plants to drought stress and cucumber downy mildew infection, downy mildew infestation at different two levels, B1 (disease infestation) and B2 (no disease infestation), along with three fertigation requirement levels, full fertigation T1, moderate nutrient solution deficit T2 and severe nutrient solution deficit T3, were applied in a greenhouse. Thus, six treatments, i.e., B1T1, B1T2, B1T3, B2T1, B2T2 and B2T3, were set. The leaf gas-exchange parameters were significantly increased under CK (control experiment, B2T1: no disease infestation and full irrigation) treatment, and leaf photosynthesis rate, transpiration rate and stomatal conductance were significantly decreased under the B1T1 treatment. Leaf intercellular CO2 concentration was significantly increased under B1T1 treatment. Leaf photosynthesis rate, transpiration rate, intercellular CO2 concentration and stomatal conductance were significantly decreased under B1T2, B1T3, B2T2 and B2T3 treatments. Compared with treatment CK (B2T1), the plant height of cucumber under B1T1, B1T2, B1T3, B2T2 and B2T3 treatments decreased by 11.41%, 19.05%, 27.48%, 7.55% and 10.62%, respectively; the stem diameter of cucumber under B1T1, B1T2, B1T3, B2T2 and B2T3 treatments decreased by 5.70%, 13.45%, 23.03%, 9.46% and 15.74%, respectively; and leaf area of cucumber under B1T1, B1T2, B1T3, B2T2 and B2T3 treatments decreased by 22.79%, 38.68%, 58.28%, 13.76% and 29.96%, respectively. The root–shoot ratio of cucumber under B1T1, B1T2, B1T3, B2T1, B2T2 and B2T3 treatments was 3.16%, 2.99%, 4.11%, 3.92%, 3.13% and 3.63%, respectively. The root–shoot ratio of cucumber was the highest under the B1T3 treatment.

Aplicação foliar de prolina no crescimento e fisiologia do milho verde cultivado em solo salinizado

Corn (Zea maysL.) is one of the most cultivated crops in the world. In Brazil, this cereal has a wide diversity of use. Most of the areas where maize production is used is irrigation, however, when performed inadequately it becomes preponderant for salinization of soils. The effect of proline foliar application on the growth and physiology of the green maize cultivated in salinized soil was evaluated. The experiment was conducted at the Center for Agro-Food Science and Technology (CCTA), belonging to the Federal University of Campina Grande (UFCG), Pombal, PB, from March to April 2015, using maize variety AG 1051.The treatments consisted of two levels of soil salinity (3.26 and 0.86 dS/m) and five concentrations of proline (0, 2.5, 5.0, 7.5 and 10 mmol L -¹) applied byleaf on corn plants. The experimental design was completely randomized, in the 2 x 5 factorial scheme, with four replications. A higher growth and mass accumulation was observed when the plants were conducted in soil of lower salinity (CE= 0.86 dS/m). Transpiration was influenced by salinity and proline concentration. The highest rate of intercellular CO2 concentration (Ci) was obtained at the concentration of 7.5 mmol L-¹ proline. Proline concentrations did not influence the growth and mass accumulation aspects of maize.

Effects of lead on growth, osmotic adjustment, antioxidant activity and photosynthetic responses in Phoebe chekiangensis seedlings

Experiments were conducted on 1-year Phoebe chekiangensis seedlings treated by different concentration (0, 300, 600, 900, 1200 mg/L) of Pb (NO3)2. Sixty days later, determination was implemented on seedling growth, physiological and photosynthetic parameters. The results showed that the lower concentration treated could promote the growth of the seedlings. But with the increase of concentration of lead, P. chekiangensis seedling height increment, ground diameter growth, whole biomass, total root surface area, root volume, total root length and root activity decreased, while root-shoot ratio present a rising trend. With the increase of concentration of Pb(NO3)2 solution, the membrane permeability and MDA content of P. chekiangensis seedlings showed a trend of rise after the first reduce; the protein content and chlorophyll content presented a trend of decrease after the first increase; while the POD, SOD and CAT activity increased firstly but decreased afterwards; the net photosynthetic rate, stomatal conductance, intercellular CO2 concentration, transpiration rate were all increase at first then decrease, which indicated that protection enzyme activity and membrane was damaged thus the growth of P. chekiangensis seedlings was inhibited.

NaCl and Na2SO4 Salinities Have Different Impact on Photosynthesis and Yield-Related Parameters in Rice (Oryza sativa L.)

To elucidate the comparative effect of chloride and sulfate salinities on photosynthesis and yield components in rice, plants of Oryza sativa (cv. I Kong Pao (salt-sensitive)) were exposed in nutrient solutions to 20 mM Na2SO4 or 40 mM NaCl (electrical conductivity of c.a. 4.30 dS m−1 for both solutions) from seedlings to maturity stage. Both types of salt induced a strong decrease in net photosynthesis (AN) at the seedling and tillering stages, while the intercellular CO2 concentrations (Ci) remained unaffected. Instantaneous transpiration (E) and stomatal conductance (gs) decreased at the tillering and seedling stages, respectively, only in plants exposed to NaCl. Chloride salinity also strongly decreased photosynthetic pigments, while no impact was detected in response to Na2SO4. All yield-related parameters were affected by salinities, but NaCl was significantly more deleterious than Na2SO4 for the mean number of tillers produced per plant, spikelets sterility and non-viable pollen percentage. In contrast, both types of salinity similarly impacted the percentage of fertile tillers and 1000-grain weight. At the grain level, more than 90% of toxic ions (Na+, excess of Cl− and S6+) accumulated in the hulls, thus preserving the internal part of the caryopses from toxic ion injuries.