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  • Author or Editor: Yang Xu x
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Lilium davidii var. unicolor Salisb is a cultivar of Lilium (Liliaceae) with important edible and ornamental characteristic. The application and production of Lilium davidii var. unicolor Salisb were still facing large problems because of its several disadvantages such as narrow range of adaptability, small annual growth increment, and low fertility. To achieve broader environmental adaptability and obtain a more nutritious germplasm, we used colchicine and oryzalin to induce chromosome doubling via the soaking method. Tissue culture bulbs were treated with colchicine at 0.03%, 0.05%, or 0.08% for 32, 40, or 48 hours or with oryzalin at 0.002%, 0.005%, 0.008%, or 0.01% for 3, 6, 9, 12, or 24 hours before being transferred to a differentiating medium. The results showed that colchicine treatment resulted in the highest induction rate when applied at 0.05% for 48 hours, whereas oryzalin treatment produced fewer tetraploid plants. The chromosome number of induced plants with small stoma density and longer guard cells is twice than that of the diploid. The plants were identified as tetraploid. In this study, a new germplasm of Lilium davidii var. unicolor Salisb was innovative and showed novel genetic characteristic.

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Two complementary DNA fragments encoding expansin genes Ad-EXP1 and Ad-EXP2 were isolated from ripening kiwifruit (Actinidia deliciosa cv. Bruno) by reverse transcription–polymerase chain reaction amplification using a pair of degenerate primers. The homology between these two expansin family members was 50% in nucleotide sequence and 74% in amino acid sequence. It was revealed that Ad-EXP1 and Ad-EXP2 belong to subgroups A and B of an expansin gene family respectively. However, gene expression of these two members shared similar patterns. Both were upregulated by ethylene treatment and downregulated by acetylsalicylic acid treatment. The study suggests that members of both subgroups A and B of the expansin family are involved in kiwifruit fruit ripening.

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Carbohydrate metabolism is important for plant adaptation to drought stress. The objective of this study was to examine major forms of carbohydrates associated with superior drought tolerance and post-drought recovery in kentucky bluegrass (Poa pratensis) by comparing responses of different forms of carbohydrates with drought stress and re-watering in two cultivars contrasting in drought tolerance. Plants of drought-tolerant ‘Midnight’ and drought-sensitive ‘Brilliant’ were maintained well watered or subjected to drought stress for 10 days by withholding irrigation, and drought-stressed plants were re-watered for 3 days. Physiological analysis (turf quality, relative water content, and electrolyte leakage) confirmed the genetic variability of the two cultivars in drought tolerance. The two cultivars exhibited differential responses to drought stress and re-watering for the content of water-soluble sugars (sucrose, fructose, and glucose) and storage carbohydrates (starch and fructan), and ‘Midnight’ maintained higher sucrose content at 10 days of drought stress and more fructan at 3 days of re-watering. The greater accumulation of sucrose in ‘Midnight’ under drought stress corresponded with higher activities of two sucrose-synthesizing enzymes (sucrose phosphate synthase and sucrose synthase) but was not related to the sucrose-degrading enzyme activity (acid invertase). These results suggested that increased sucrose accumulation resulting from the maintenance of active sucrose synthesis could be associated with superior turf performance during drought stress, whereas increased fructan accumulation could contribute to rapid re-growth and post-drought recovery on re-watering in kentucky bluegrass.

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High temperature and high relative humidity (RH) are one of the most serious agricultural meteorological disasters that limit the production capacity of agricultural facilities. However, little information is available on the precise interaction between these factors on tomato growth. The objectives of this study were to determine the effect of high temperature under different RH levels on tomato growth and endogenous hormones and to determine the optimal RH for tomato seedling growth under high temperature environment. Two high temperature (38/18 °C, 41/18 °C) and three relative humidity (50 ± 5%, 70 ± 5%, 90 ± 5%) orthogonal experiments were conducted, with 28/18 °C, 50 ± 5% (CK) as control. The results showed that the dry matter accumulation of tomato plants under high temperature environment was significantly lower than that of CK. At 38 °C, the dry matter accumulation with 70% relative humidity was not significantly different from that of CK; at 41 °C, dry matter accumulation with 70% and 90% relative air humidity was significantly greater than that of 50%. The concentrations of soluble sugar and free amino acids in all organs in high temperature-treated plants were significantly higher than that in CK. As relative humidity increased, soluble sugar concentrations of each organ decreased, and the free amino acid concentrations increased. Cytokinin (ZT) and indole acetic acid (IAA) concentrations in tomato buds were significantly lower than in CK under high temperature conditions. The lower the RH, the lower the content of ZT and IAA. The gibberellin (GA3) and abscisic acid (ABA) concentrations were higher than in CK under high temperatures. GA3 concentrations decreased and ABA concentrations were augmented with increased humidity. The differences of tomato seedling growth indices and apical bud endogenous hormone concentrations between RHs under high temperature conditions were significant. Raising RH to 70% or higher under high temperature conditions could be beneficial to the growth of tomato plants. The results contribute to a better understanding of the interactions between microclimate parameters inside a Venlo-type glass greenhouse environment, in a specific climate condition, and their effects on the growth of tomato.

Open Access

The purpose of this experiment was to determine the response of tomato (Solanum lycopersicum L.) cultivars with fruit of average and high lycopene to increased K fertilization. The field experiment was designed as a factorial, split-plot, randomized complete block with four replications. The main plot consisted of K rates ranging from 0 to 372 kg·ha−1 K as KCl, and the subplot was cultivar (‘Mountain Spring’ or the high-lycopene Florida hybrid, ‘Fla. 8153’). The soil type was a well-drained, central Iowa loam with a soil test level considered low. The soil K application effect on total marketable fruit yield was linear (P < 0.001, Y = 53 Mg·ha−1 + 0.084x, r2 = 0.51) with both cultivars responding similarly. Fruit K analysis indicated a linear response to fertilization across four harvest dates, from 1236 to 1991 mg·kg−1, fresh weight basis. Harvest date had no effect on fruit lycopene concentration, but there was a significant (P = 0.006) interaction of K fertilization rate and cultivar. Overall, ‘Fla. 8153’ contained 9.5 mg·kg−1 more lycopene in fruit tissue than ‘Mountain Spring’. ‘Mountain Spring’ lycopene concentration was not enhanced by higher K fertilization (44.2 mg·kg−1). ‘Fla. 8153’ lycopene concentration increased 21.7% at the highest K rate compared with lower rates (62.9 vs. 51.7 mg·kg−1, respectively). A controlled greenhouse study in the fall of 2005 with the same cultivars indicated similar results. Fruit K concentration for ‘Fla. 8153’ was significantly (P < 0.01) correlated to the fruit carotenoids, phytoene and phytofluene, indicating a possible role for K in one of the enzymes that synthesize phytoene. In the field and greenhouse studies, increasing fruit K concentration in the high-lycopene ‘Fla. 8153’ depressed fruit β-carotene by 53%. These results indicate that K fertilization can affect carotenoid biosynthesis, and the response of tomato to a high K rate is genotype dependent.

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White rust (causative pathogen Puccinia horiana) is a destructive disease of commercial chrysanthemum crops. A panel of 19 accessions of commercial chrysanthemum near-relatives (four Ajania species, 11 Chrysanthemum species including five accessions of Chrysanthemum indicum) were screened for their reaction to white rust infection in separate greenhouse trials carried out at two independent sites in eastern China, one in 2010 and the other in 2012. The reaction of the accessions to artificial inoculation ranged from immune to highly susceptible. Accessions of Chrysanthemum indicum, C. yoshinaganthum, C. makinoi var. wakasaense, C. nankingense, C. vestitum, C. lavandulifolium, C. crassum, and Ajania tripinnatisecta were immune, and strong resistance was present in C. japonense, C. × shimotomaii, and A. przewalskii. Most of the accessions behaved similarly in the two trials, but two of the C. indicum accessions produced inconsistent results, each being highly resistant in one trial but susceptible in the other. Because wide crosses are relatively easy to achieve in the chrysanthemum complex, these immune and highly resistant accessions represent promising germplasm for white rust resistance breeding.

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In this investigation, changes in growth and photosynthetic parameters were used to explain the effects of drought stress on morphology and photosynthesis of Eleutherococcus senticosus. Liquid chromatography (LC)-mass spectroscopy (MS) was used to determine the content of eleutheroside B, eleutheroside E, isofraxidin, hyperoside, rutin, and kaempferol under different drought stress conditions to explain the effects of drought stress on secondary metabolism of Eleuthero. Growth and photosynthetic physiological parameters showed that drought stress could inhibit the growth and photosynthesis of Eleuthero. The compounds studied showed the same cumulative trend in various organs of Eleuthero under different drought stress conditions, with the highest content in the moderate drought stress group and the lowest in the severe drought stress group. Among them, the content of eleutheroside B was found to be higher in the 5-year-old stem. The content of eleutheroside E was higher in the 3-year root. The content of isofraxidin was highest in the 5-year-old root. The content of hyperoside, rutin, and kaempferol were higher in the 3-year-old leaves. The results show that a wet soil environment was beneficial to growth and photosynthesis of Eleutherococcus senticosus, and moderate drought stress is conducive to the accumulation of its active ingredients.

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Although atmospheric evaporative demand mediates water flow and constrains water-use efficiency (WUE) to a large extent, the potential to reduce irrigation demand and improve water productivity by regulating the atmospheric water driving force is highly uncertain. To bridge this gap, water transport in combination with plant productivity was examined in cucumber (Cucumis sativus L.) grown at contrasting evaporative demand gradients. Reducing the excessive vapor pressure deficit (VPD) decreased the water flow rate, which reduced irrigation consumption significantly by 16.4%. Reducing excessive evaporative demand moderated plant water stress, as leaf dehydration, hydraulic limitation, and excessive negative water potential were prevented by maintaining water balance in the low-VPD treatment. The moderation of plant water stress by reducing evaporative demand sustained stomatal function for photosynthesis and plant growth, which increased substantially fruit yield and shoot biomass by 20.1% and 18.4%, respectively. From a physiological perspective, a reduction in irrigation demand and an improvement in plant productivity were achieved concomitantly by reducing the excessive VPD. Consequently, WUE based on the criteria of plant biomass and fruit yield was increased significantly by 43.1% and 40.5%, respectively.

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