Effects of rotted corn straw on soil environment, yield, and quality of cucumber.

Aiming at solving the problems of soil environment deterioration and the decline of both yield and quality caused by excessive application of chemical fertilizer, we investigated the effects of rotted corn straw on the soil environment of root zone, yield and quality of cucumber with 'Jinyou 35' cucumber as the experimental material. There were three treatments, namely, combined application of rotted corn straw and chemical fertilizer (T, the total nitrogen fertilizer application were 450 kg N·hm, of which 9000 kg·hm rotted corn straw was used as the subsoil fertilizer, and the rest was supplemented with chemical fertilizer), pure chemical fertilizer (T, the total nitrogen fertilizer application was the same as T) and no fertilization (control). The results showed that the content of soil organic matter in root zone soil in T treatment was much higher, but no difference between T treatment and the control, after two continuous plantings in one year.

Comparative transcriptome analysis of grafting to improve chilling tolerance of cucumber.

Grafting with pumpkin as rootstock could improve chilling tolerance of cucumber; however, the underlying mechanism of grafting-induced chilling tolerance remains unclear. Here, we analyzed the difference of physiological and transcriptional level between own-rooted (Cs/Cs) and hetero-grafted (Cs/Cm) cucumber seedlings under chilling stress. The results showed that grafting with pumpkin significantly alleviated the chilling injury as evidenced by slightly symptoms, lower contents of electrolyte leakage (EL), malondialdehyde (MDA), hydrogen peroxide (HO), and superoxide anion (O) and higher relative water content in Cs/Cm seedlings compared with Cs/Cs seedlings under chilling stress.

[Alleviating effect of exogenous melatonin and calcium on the peroxidation damages of cucumber under high temperature stress].

To explore whether there is an interaction between melatonin (MT) and calcium (Ca) in regulating heat tolerance of plants, we analyzed the response of endogenous MT and Ca to heat stress, and examined the effect of MT and Ca on the reactive oxygen (ROS) accumulation, antioxidant system, and transcripts of heat shock factor () and heat shock proteins () of cucumber seedlings under high temperature stress. Seedlings were foliar sprayed with 100 μmol·L MT, 10 mmol·L CaCl, 3 mmol·L ethylene glycol tetraacetic acid (EGTA, Ca chelating agent) +100 μmol·L MT, 0.05 mmol·L chlorpromazine (calmodulin antagonist, CPZ) +100 μmol·L MT, 100 μmol·L p-chlorophenylalanine (p-CPA, inhibitor of MT) +10 mmol·L CaCl or deionized water (HO), respectively.

[Effects of fulvic acid on photosynthetic characteristics, yield and quality of cucumber under drought stress].

Fulvic acid (FA) participates in the regulation of drought stress tolerance in plants, but the underlying mechanisms remain unclear. We carried out an experiment with cucumber cultivar 'Jinyou 35' as the test material and the polyethylene glycol (PEG-6000) being used to simulate drought stress. The concentration effect of FA on drought alleviation of cucumber as well as the effect of FA on photosynthetic enzymes activities, chloroplast ultrastructure, fluorescence parameters, water use efficiency, yield and quality of cucumber plants were studied through spraying FA with different concentrations (0, 100, 300, 500, 700 and 900 mg·L).

Salicylic Acid Is Involved in Rootstock-Scion Communication in Improving the Chilling Tolerance of Grafted Cucumber.

Salicylic acid (SA) has been proven to be a multifunctional signaling molecule that participates in the response of plants to abiotic stresses. In this study, we used cold-sensitive cucumber and cold-tolerant pumpkin as experimental materials to examine the roles of SA in root-shoot communication responses to aerial or/and root-zone chilling stress in own-root and hetero-root grafted cucumber and pumpkin plants. The results showed that pumpkin () rootstock enhanced the chilling tolerance of grafted cucumber, as evidenced by the observed lower levels of electrolyte leakage (EL), malondialdehyde (MDA), and higher photosynthetic rate (Pn) and gene expression of Rubisco activase (RCA).

[Hydrogen sulfide acted as a downstream signal was involved in the regulation of salicylic acid on photosynthesis of cucumber seedlings under low temperature and low light intensity].

Both salicylic acid (SA) and hydrogen sulfide (HS) play an important role in regulating plant growth and development and physiological metabolism under abiotic stresses. As signal molecules, the interaction between them in regulating cucumber photosynthesis under low temperature and low light is still unclear. Here, we examined the regulation and interaction of SA and HS on photosynthesis in cucumber seedlings under low temperature (8 ℃/5 ℃, day/night) and low light (100 μmol·m·s).

Hydrogen sulfide is required for salicylic acid-induced chilling tolerance of cucumber seedlings.

Salicylic acid (SA) and hydrogen sulfide (HS) have been proved to be multifunctional signal molecules to participate in the response of plants to abiotic stresses. However, it is still unclear whether there is interaction between SA and HS in response to chilling intensity of cucumber seedlings. Here, we found SA was sensitive to chilling intensity.

Auxin acts as a downstream signaling molecule involved in hydrogen sulfide-induced chilling tolerance in cucumber.

This report proves a cross talk between HS and IAA in cold stress response, which has presented strong evidence that IAA acts as a downstream signal mediating the HS-induced stress tolerance in cucumber seedlings. We evaluated changes in endogenous hydrogen sulfide (HS) and indole-3-acetic acid (IAA) emission systems, and the interactive effect of exogenous HS and IAA on chilling tolerance in cucumber seedlings. The results showed that chilling stress increased the activity and relative mRNA expression of L-/D-cysteine desulfhydrase (L-/D-CD), which in turn induced the accumulation of endogenous HS.

[Effects of light quality on carbon-nitrogen metabolism, growth, and quality of Chinese chives].

We examined the effect of white + red (WR), white + blue (WB), white + green (WG), white + purple (WP) on the carbon-nitrogen metabolism, growth and quality of Chinese chives, with ‘Pingjiu 2’ as the material and white light (W) as the control. The results showed that photosynthetic rate (P) in WR treatment was significantly higher than that in the control (CK) and that there was no difference among WB, WG, WP and CK. The activity of RuBPCase in all the four treatments was higher than that in CK.

[Effects of light quality ratio on photosynthetic characteristics and quality of purple lettuce].

To explore the effects of different light quality ratios on the growth and development of purple lettuce, we used LED intelligent light control console as light source to study the effects of adding different proportions of red and blue light (1:1, 2:1, 4:1 and 1:2) to the white light on photosynthetic characteristics and commercial quality of purple lettuce (Lactuca sativa L. cv 'Zhongshu Purple Lettuce'). The results showed that when the ratio of red to blue light was 4:1, the chlorophyll content, RuBP carboxylase activity, electron transport efficiency of photosynthesis, net photosynthetic rate and growth were all significantly higher than that in control and other treatments, whereas the nitrate content was the lowest.

[Response and adaptation of photosynthesis of cucumber seedlings to high temperature stress].

Cucumber seedlings (Cucumis sativus Jinyou 35) were used to study the effects of high temperature (HT: 42 ℃/32 ℃) and sub-high temperature (SHT: 35 ℃/25 ℃) on its photosynthesis and growth. The results showed that the growth of cucumber seedlings was dramatically inhibited by the high and sub-high temperature stresses. The photosynthetic rate (P) was gradually reduced, while intercellular CO concentration (C) was increased as heat stress lasted.

[Effect of water-nitrogen coupling on photosynthesis and ultrastructure of cucumber leaves under CO enrichment].

Using split plot and then-split plot design, effects of water-nitrogen coupling on photosynthesis and ultrastructure of cucumber (Cucumis sativus) (Jinyou No.35) under CO enrichment were investigated. The main plot had two CO concentrations: ambient CO concentration (400 μmol·mol, A) and doubled CO concentration (800±20 μmol·mol, E).

[Effects of light quality on growth, secondary metabolites, and oxidative stress tolerance of Gynura bicolor.].

The effects of white light, red light, blue light, yellow light, red+blue light and red+blue+yellow light on the growth and quality of Gynura bicolor were investigated under the same light intensity (350±5 μmol·m·s) by using light-emitting-diodes (LEDs) which could accurately regulate light quality and light intensity. The results indicated that compared with white light, red light could significantly promote the growth of G. bicolor and induce the accumulation of dry substance and soluble sugar content, but blue light inhibited the plant growth.

[Effect of grafting on rhizosphere soil environment and its relationship with disease resistance and yield of pepper.].

We investigated the effect of grafting on the root rhizosphere soil microorganisms, physical properties, nutrient content, soil-borne disease and yield of pepper, using 'Weishi' (WS) and 'Buyeding' (BYD) as rootstocks, the cultivar pepper 'Xinfeng 2' (XF) as scion, and the own-root (XF/XF) pepper as the control. The results indicated that XF/WS and XF/BYD significantly increased the populations of fungi and actinomycetes and the percentage of actinomycetes. 60 days after transplanting, the activities of catalase (CAT) and peroxidase (POD) were much higher in root rhizosphere soil of grafted pepper.

Ultraviolet-B Radiation (UV-B) Relieves Chilling-Light-Induced PSI Photoinhibition And Accelerates The Recovery Of CO Assimilation In Cucumber (Cucumis sativus L.) Leaves.

Ultraviolet-B radiation (UV-B) is generally considered to negatively impact the photosynthetic apparatus and plant growth. UV-B damages PSII but does not directly influence PSI. However, PSI and PSII successively drive photosynthetic electron transfer, therefore, the interaction between these systems is unavoidable.

[Influence of over expression of CsRCA on photosynthesis of cucumber seedlings under high temperature stress.].

In the present work, transgenic cucumber seedlings over expressing CsRCA and wild-type cucumber seedlings '08-1'at three-leaf stage exposed to high temperature (40 ℃, PFD 600 μmol· m · s) were used to study the regulatory mechanism of photosynthesis by CsRCA. The results showed that the mRNA abundance of rbcL and rbcS as well as the activities of ribulose bisphosphate carboxylic enzyme (Rubisco) and Rubisco activase (RCA) were significantly higher in CsRCA over-expressing cucumber seedlings than in wild type (WT). Following 2-h exposure to high temperature, a notable decrease was observed in photosynthetic rate (P), photochemical perfor-mance index based on the absorption of light energy (PI), activities of Rubisco and RCA as well as the relative expression of rbcL, rbcS and CsRCA in both wild-type cucumber seedlings and transgenic cucumber seedlings.

[Effects of low magnesium on photosynthesis characteristics and antioxidant system in cucumber seedlings under low temperature].

The effects of low magnesium (30% Mg) stress on photosynthesis characteristics and antioxidant system in 'Jinyou 3' cucumber ( Cucumis sativa) seedlings under low temperature (day/ night temperature was 12 °C/8 °C) were investigated, with Hoagland nutrient solution treatment as the control. The results showed that the 30% Mg treatment showed a significantly lower Mg content in leaves, compared with the control. However, no marked difference in roots between the 30% Mg treatment and the control was found.

Water Status Related Root-to-Shoot Communication Regulates the Chilling Tolerance of Shoot in Cucumber (Cucumis sativus L.) Plants.

Although root-to-shoot communication has been intensively investigated in plants under drought, few studies have examined root-to-shoot communication under chilling. Here we explored whether root-to-shoot communication contributes to the chilling-light tolerance of cucumber shoots and clarified the key signal involves in this communication. After leaf discs chilling-light treatment, the photoinhibitions of Photosystem I (PSI) and Photosystem II (PSII) were similar in leaf discs of two cucumber varieties (JY-3 and JC-4).

[Responses of non-structural carbohydrate metabolism of cucumber seedlings to drought stress and doubled CO2 concentration].

The effects of doubled CO2 concentration on non-structural carbohydrate metabolism of cucumber (Cucumis sativus L. cv. 'Jinyou No.

[Distribution and accumulation characteristics of nutrients in solar greenhouse soil in Ji'nan, Shandong Province of East China].

Taking the solar greenhouses with different cultivating years and vegetables in Ji'nan as test objects, this paper studied the amounts and frequency distribution of soil nutrients and the relationships between cultivating years and soil nutrients accumulation characteristics, and analyzed the factors causing soil salinization and acidification by fitting soil nutrients contents with cultivating years and vegetables. In the greenhouses, the contents of soil alkali-hydrolysable nitrogen, available phosphorus, available potassium, organic matter, and electrical conductivity were significantly higher than those in the open field, with an increment of 135.3%, 475.

[Impacts of suboptimal temperature and low light intensity on the activities and gene expression of photosynthetic enzymes in cucumber seedling leaves].

Taking the cucumber cultivar 'Jinyou 3' as test material, this paper studied the variations of the mRNA expression and activities of ribulose-1, 5-bisphosphate carboxylase/oxygenase (Rubisco), fructose-1, 6-bisphosphatase (FBPase), glyceraldehydes-3-phosphate dehydrogenase (GAPDH), fructose-1, 6-bisphosphate aldolase (FBA), and transketolase (TK) in cucumber seedling leaves under suboptimal temperature and low light intensity (ST+LL). In the treatment of ST+LL, the leaf area and the dry mass per plant decreased remarkably, compared with the control. On the early days of ST+LL treatment, the gene expression of Rubisco rbcL and rbcS, FBPase, GAPDH, FBA, and TK declined markedly, the activities of the enzymes except TK obviously weakened, and the photosynthetic rate (P(n)) decreased rapidly.

[Responses of Rubisco and Rubisco activase in cucumber seedlings to low temperature and weak light].

Using 'Jinyou 3' cucumber seedlings as test materials, this paper studied their photosynthetic rate (P(n)), Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) and Rubisco activase (RCA) activities, and gene expression of Rubisco and RCA under optimal temperature and weak light (WL: 25 degrees C/18 degrees C, 100 micromol x m(-2) x s(-1)), suboptimal temperature and weak light (ST+WL: 18 degrees C/12 degrees C, 100 micromol x m(-2) x s(-1)), and low temperature and weak light (LT+WL: 10 degress C/5 degrees C, 100 micromol x m(-2) x s(-1)). Comparing with the control (25 degrees C/18 degrees C, 400 micromol x m(-2) x s(-1)), treatments WL, ST+WL, and LT+WL all led to a remarkable decrease in leaf area and dry matter mass. At initial stage, the P(n), Rubisco activity, rbcL and rbcS expression, RCA activity, and CsRCA expression in the three treatments declined by a big margin; 5-7 days later, these parameters tended to be less changed in treatment WL, ascended slowly in treatment ST+WL, and decreased continuously in treatment LT+WL.

[Effects of graft on lipid peroxidation and antioxidative enzyme activities of Capsicum annum seedlings under low temperature and weak light intensity].

Taking 'Chifengtexuan' as scion and 'Weishi' as rootstock, this paper studied the changes in the electrolyte leakage (EL), malondialdehyde (MDA) content, antioxidative enzyme activities, and root activity of own-rooted and grafted Capsicum annuum seedlings under 1-7 days low temperature (8 degrees C/ 5 degrees C) and weak light intensity (100 micromol x m(-2) x s(-1) stress and after 1-3 d recovery. During the early stress days, the EL, MDA content, and activities of superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidase (APX) and glutathione reductase (GR) in both own-rooted and grafted seedlings leaves and roots increased, but the root activity decreased significantly. 1-3 days later, grafted seedlings showed a stable state in EL and MDA content, a decrease in SOD, POD, APX, and GR activities, and an increasing trend in root activity.

[Effects of grafting on photosynthesis of sweet pepper seedlings under low temperature and weak light intensity].

Sweet pepper 'Chifengtexuan' seedlings were grafted onto 'Weishi' and 'Buyeding' rootstocks, treated with low temperature (8 degrees C/ 5 degrees C) and weak light intensity (100 micromol x m(-2) s(-1)) for 7 days, and then recovered under normal conditions (25 degrees C/ 18 degrees C, PFD 550-600 micromol x s(-1)) for 3 days to study the variations of their gas exchange parameters, carboxylation efficiency, and fluorescence parameters, with the own-rooted 'Chifengtexuan' seedlings as the control. The results showed that on the 3rd day of low temperature and weak light intensity stress, the photosynthetic rate (Pn), stomatal conductance (Gs), and carboxylation efficiency (CE) of both own-rooted and grafted seedling leaves decreased more than 50%, and after then, the Pn and Gs tended to stable while CE decreased continually. The intercellular CO2 concentration (Ci) declined first, but enhanced after the 4th day of the stress.

[Effects of salicylic acid on the leaf photosynthesis and antioxidant enzyme activities of cucumber seedlings under low temperature and light intensity].

In order to elucidate the regulation functions of salicylic acid (SA) on the photosynthesis of cucumber under low temperature and light intensity, the seedlings of cucumber 'Jinyou 3' under low temperature and light intensity were foliar-sprayed with different concentration SA, and the leaf gas exchange parameters, photochemical efficiency, MDA content, and antioxidant enzyme activities were measured. The results showed that under low temperature and light intensity, the leaf photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), actual photochemical efficiency of PS II (PhiPSII), and maximal photochemical efficiency of PS II (Fv/Fm) of the seedlings all decreased but the intercellular CO2 concentration (Ci) increased, suggesting that nonstomatal limitation was the main cause of the decrease of Pn under low temperature and light intensity stress. Low temperature and light intensity also led to the increase of leaf malondialdehyde (MDA) content and superoxide dismutase (SOD) activity, the decrease of catalase (CAT) activity, and the decrease after an initial increase of peroxidase (POD) activity.