Potassium deficiency is a major problem limiting tobacco (Nicotiana tabacum) growth, and grafting has the potential to alleviate it. To compare the photosynthetic performance of grafted tobacco under different potassium levels, tobacco Yunyan 87 (main cultivar) and Wufeng No. 2 (potassium high-efficiency cultivar) were selected to conduct mutual grafting trials in the form of hydroculture with two potassium supply levels (5 mmol·L−1 K and 0.5 mmol·L−1 K). The plant growth, gas exchange parameters, chlorophyll a fluorescence, and the initial ribulose-1,5-bisphosphate carboxylase-oxygenase (RuBisCO) activity were measured. The results showed that potassium deficiency could significantly decrease the net photosynthetic rate, stomatal conductance (g S), and transpiration rate in the tobacco leaves, resulting in nonstomatal restriction. Grafting could effectively alleviate this problem. The actual quantum yield of photosystem II (PSII) photochemicals in ‘Yunyan 87’ increased 29.4% and 20.3% by grafting, respectively, under normal and low potassium levels. Compared with nongrafted ‘Yunyan 87’, grafting also effectively improved the electron transfer efficiency of PSII in the tobacco leaves under low potassium stress by reducing nonradiation energy dissipation and enhancing the initial activity of RuBisCO. From this study, it can be known that grafted tobacco plants can improve their photosynthesis by alleviating the nonstomata restriction of leaves under potassium stress and improving the electron transfer efficiency of PSII.
Wei Hu, Qing Di, Jingyi Wei, Jie Zhang, and Jia Liu
Qiang Zhang, Minji Li, Beibei Zhou, Junke Zhang, and Qinping Wei
This study aimed to understand the effects of meteorological factors on the ‘Fuji’ apple quality in the Circum-Bohai and Loess Plateau apple production regions of China and to guide apple production based on local climate. Fruit samples of the ‘Fuji’ apple and meteorological data were investigated from 132 commercial ‘Fuji’ apple orchards covering 44 counties in the two aforementioned production regions (22 counties per region). The partial least-squares regression (PLSR) method was first used to screen major meteorological factors that greatly affected fruit quality; these were subsequently used to establish the regression equation of fruit quality attributes and major meteorological factors. Linear programming was used to estimate optimum meteorological factors for good apple quality. The results showed that in the Circum-Bohai production region, many meteorological factors (total annual precipitation, total precipitation from April to October, lowest temperature from April to October, sunshine percentage from April to October) were significantly higher than those in the Loess Plateau production region; however, the temperature difference between day and night from April to October was significantly smaller than that in the Loess Plateau production region. The soluble solids content and skin color area of apples from the Loess Plateau production region were significantly greater than those from the Circum-Bohai production region. The same fruit quality factor of ‘Fuji’ apple was affected by different meteorological factors in the two production regions. The monthly mean temperature and monthly highest temperature from April to October of the Circum-Bohai production region had relatively larger positive effect weights on fruit quality, whereas the total annual precipitation, monthly mean relative humidity from April to October, and total precipitation from April to October of the Loess Plateau production region had relatively larger positive effect weights on fruit quality. The major influencing meteorological factors of the fruit soluble solids content were total precipitation from April to October (X 7), mean annual temperature (X 1), and the monthly highest temperature from April to October (X 5) in the Circum-Bohai production region; however, it included the monthly mean temperature difference between day and night from April to October (X 6), total annual precipitation (X 2), and total precipitation from April to October (X 7) in the Loess Plateau production region. In the Circum-Bohai production region, the optimum meteorological factors for ‘Fuji’ fruit quality of vigorous apple orchards were the mean annual temperature (13.4 °C), total annual precipitation (981 mm), monthly mean temperature (16.8 to 22.4 °C), lowest temperature (11.9 °C), highest temperature (19.5 to 26.8 °C), temperature difference between day and night (12.3 °C), total precipitation (336–793 mm), relative humidity (55.7% to 70.7%), and sunshine percentage (42.3% to 46.1%) during the growing period (April–October). In the Loess Plateau production region, the optimum meteorological factors for ‘Fuji’ fruit quality of vigorous apple orchards were the mean annual temperature (5.5 to 11.6 °C), total annual precipitation (714 mm), monthly mean temperature (13.3 to 19.9 °C), lowest temperature (7.9 to 9.3 °C), highest temperature (19.6 to 27.3 °C), temperature difference between day and night (7.1 to 12.4 °C), total precipitation (338–511 mm), relative humidity (56.1% to 82.4%), and sunshine percentage (37.3% to 55.9%) during the growing period (April–October). The restrictive factors for high-quality ‘Fuji’ apples of the Circum-Bohai production region were the smaller monthly mean temperature difference between day and night, higher monthly mean lowest temperature, and larger monthly mean relative humidity during the growing period; however, those of the Loess Plateau production region were drought or less precipitation from November to March, lower monthly mean temperature, and higher monthly mean highest temperature during the growing period.
Liping Zhang, Chen Shen, Jipeng Wei, and Wenyan Han
6-Benzyladenine (6-BA) is a safe and efficient cytokinin. The adult tea plants of the cv. Longjing 43 were used in this study. The foliar portion of tea bushes were sprayed with different concentrations (50, 100, 200, or 400 mg·L−1) of 6-BA after heavy pruning, when three to four leaves grew out in late May. The effects of 6-BA application on the growth of the new shoots and lateral branches were quantified. After 5 months, treatments with 50, 100, 200, or 400 mg·L−1 6-BA suppressed plant height by 11.0%, 18.0%, 21.0%, or 22.0%, respectively; 6-BA at 100, 200, or 400 mg·L−1 decreased the number of lateral branches by 20.0%, 23.0%, or 18.0%, respectively. Meanwhile, treatments with 50, 200, or 400 mg·L−1 6-BA increased the length of lateral branches by 38.0%, 79.0%, or 81.0% respectively; 200 mg·L−1 6-BA increased the diameter of lateral branches by 8.0%. In addition, after 2 months, 50 or 200 mg·L−1 6-BA did not significantly affect the growth of functional leaves, 50, 100, or 200 mg·L−1 6-BA did not significantly affect photosynthetic rate (Pn) as compared with the control. Furthermore, 200 or 400 mg·L−1 6-BA significantly increased spring tea yield by 28.9% or 13.3%, respectively as compared with the control. In conclusion, 6-BA at the four concentrations promoted dwarfing and the formation of productive lateral branches and increased the spring yield, and 200 mg·L−1 6-BA exerted the best comprehensive effect.
Junhuo Cai, Junjun Fan, Xuying Wei, and Lu Zhang
Lycoris radiata has beautiful bright-red flowers with both medicinal and ornamental value. However, the mechanisms underlying an unusual characteristic of Lycoris radiata, flowering without leaves, remain unclear. In this study, climatic influences, biomass composition, and yearly variations in bulb contents across eight developmental stages of L. radiata were analyzed. Thus, L. radiata summer dormancy was investigated in three dimensions: climate-associated phenology, biomass distribution characteristics, and physiologic bulb changes. The results showed that dormancy was most strongly affected by high ambient temperature, followed by scape development, flowering, leafing out, vigorous leaf growth, flower bud differentiation, flower bud predifferentiation, and leaf maturation. Biomass allocation, bulb contents, oxidoreductase activity, and root activity fluctuated significantly in L. radiata among developmental stages. Relative bulb dry weight was greatest during the dormant period (95.95% of total dry weight) and lowest during vigorous leaf growth (November–December). Root biomass was also significantly greater during dormancy than during flowering, leaf maturation, and flower bud differentiation. Only root biomass during vigorous leaf growth was greater than root biomass during dormancy. However, in dormant bulbs, soluble sugar content, soluble protein content, root activity, superoxide dismutase (SOD) activity, and peroxidase (POD) activity decreased. Thus, summer dormancy in L. radiata only constitutes a morphologic dormancy of the aboveground plant; the bulb and root remain physiologically active. The results suggest that L. radiata is sensitive to both ambient temperature and light, and that summer dormancy is triggered by the synergistic stimulation of these two factors. Although temperature controls dormancy, it plays only a limited regulatory role during the L. radiata flowering period. Thus, it is difficult to induce flowering or regulate annual flowering in this species through temperature control alone.
Meng Wei, Aijun Zhang, Hongmin Li, Zhonghou Tang, and Xiaoguang Chen
Nitrogen (N) is an essential macronutrient limiting plant growth and quality of leaf-vegetable sweetpotato (Ipomoea batatas Lam). The objective of this study was to investigate the effects of N deficiency and re-supply on growth, physiology, and amino acids in sweetpotato. Two leaf-vegetable sweetpotato cultivars, Pushu 53 and Tainong 71, were subjected to three treatments in hydro-culture: 1) N sufficiency, 2) N deficiency, and 3) N deficiency and subsequently with N re-supply. Compared with N sufficiency, N deficiency caused a decrease in vine growth, carotenoid and chlorophyll content (Chlt), root viability, photosynthesis, and nitrate reductase (NR) activity in both cultivars, but to a great extent in Tainong 71. Whereas N deficiency increased root growth and glutamine synthetase (GS) activity in both cultivars, and the increase in ‘Tainong 71’ was more obvious. Re-supply of N recovered the vine growth, root viability, Chlt, photosynthesis, NR, and GS activity, to a greater extent for ‘Pushu 53’ than for ‘Tainong 71’. N deficiency significantly decreased essential amino acids, including lysine, phenylalanince, isoleucine, tryptophane, leucine, and valine contents and nonessential amino acids, consisting of glutamic acid, aspartic acid, glycine, argnine, and proline content in both cultivars. These results indicated that the light leaf color leafy sweetpotato ‘Tainong 71’ is sensitive to the N availability and the dark green leaf color ‘Pushu 53’ is more tolerant to low N, which appear to reflect the differential response of two cultivars to their different adaptability to N availability.
Jin-wei Zhang, Yi-xue Liu, Jin-ping Yu, Wei Zhang, Ya-qiong Xie, and Ning-ning Ge
In the early Spring of 2015 and 2016, weed infestation surveys were conducted in areas of cool-season turfgrass Festuca arundinacea Schreb. at 23 sites within Tianjin municipality in northern China. The weed community within turfgrass areas comprised 37 weed species belonging to 14 families. Perennial weeds accounted for 45.9% of the total community of weed species, whereas annual or biennial weeds accounted for 54.1%. Asteraceae was the dominant family (43.2%), and the percentage of broadleaved weeds was 94.6%. Statistical analyses of the weed dominance index (integrating weed relative height and relative coverage) and relative abundance (integrating weed relative density, frequency, and uniformity) showed that the 10 most common weed species during the early spring were Ixeris polycephala Cass., Taraxacum mongolicum Hand.-Mazz., Inula japonica Thunb., Hemistepta lyrata Bge., Trigonotis pedunclaris (Trev.) Benth., Calystegia hederacea Wall., Lepidium apetalum Willd., Plantago asiatica L., Cirsium segetum Bge., and Ixeris sonchifolia Hance. Ixeris polycephala Cass. and T. mongolicum Hand.-Mazz were the most dominant and harmful weed species. Partial correlation analysis (PACA) indicated that the deterioration rate (percentage of bare soil or coverage of plants other than turfgrass) of the turfgrass area was significantly and positively correlated with the total dominance index [(TDI), an index to evaluate the weed infestation severity)] and that the soil organic matter (SOM) and salinity factors were negatively correlated with the TDI. Factors such as soil nutrient conditions (the contents of N, P, and K and the total N), soil physical properties (density and clay content), soil moisture, soil temperature, and soil pH did not correlate significantly with the TDI. We conclude that the deterioration rate was the most important factor influencing weed infestation in the early spring and that SOM and soil salinity might also be important factors. The results of this study can help turfgrass researchers and managers identify the most harmful weed species and integrate management strategies in areas of cool-season turfgrass F. arundinacea Schreb. during early spring in the Tianjin region, China.
Xu Zhang, Na Ta, Wei-ye Tian, Li-jun Gao, and Wei Jiao
The marginal soil temperature on the south side of a greenhouse remains at low temperatures in winter for long periods, which affects crop growth and land-use efficiency, it is of great significance to grasp the influencing factors of soil temperature change to improve the marginal soil temperature on the south side of the greenhouse. This study was conducted in at typical greenhouse in the cold and arid area of northern China and used the Grey Relational Analysis (GRA) method, the relational degree between the marginal soil temperature on the south side of the greenhouse and environmental factors under different lining structures was analyzed, and established the soil temperature transfer function. The results show that soil temperature had the greatest correlation with the soil humidity and air humidity inside and outside the greenhouse, and the second greatest correlation was the relation with the air temperature inside and outside the greenhouse and the outdoor soil temperature; the lining structure could effectively reduce the relation between soil temperature and humidity inside and outside the greenhouse. Polystyrene extruded board (PEB) had a greater degree of relational reduction than other lining materials in the test. Through verification analysis, the mean absolute error of soil temperature of 5 cm was less than 0.85 °C, the average absolute error of soil temperature at 15 cm was less than 0.57 °C, and the average absolute error of soil temperature at 25 and 55 cm was less than 0.2 °C. In conclusion, the constructed soil temperature transfer function could be used to predict the variation trend of soil temperature, and the PEB material lining structure had good thermal insulation.
Xu-Wen Jiang, Cheng-Ran Zhang, Wei-Hua Wang, Guang-Hai Xu, and Hai-Yan Zhang
The effects of CaCl2, GA3, and H2O2 priming on Isatis indigotica Fort. seed germination characteristics, seedling growth parameters, and antioxidant enzyme activities under salt stress were investigated. NaCl had an adverse effect on the germination and seedling performance of I. indigotica. However, these three priming agents alleviated salt stress by increasing the germination percentage, improving seed vigor, accelerating germination velocity, and establishing strong seedlings. The optimal concentrations were 15 g/L for CaCl2, 0.2 g/L for GA3, and 40 mm for H2O2. Seed priming treatments enhanced the activities of antioxidant enzymes in seedlings, such as superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), under a salt environment, which reduced the oxidative injury caused by salt. Seed priming is a promising technique that can enhance the ability of I. indigotica seed germination when salt is present.
Bingqiang Wei, Lanlan Wang, Paul W. Bosland, Gaoyuan Zhang, and Ru Zhang
A cytoplasmic male sterility (CMS) system is one of the most efficient ways to produce F1 hybrid seeds in pepper (Capsicum annuum). Restorer-of-fertility (Rf) genes are a critical component within the CMS/Rf system. The inheritance of Rf genes in pepper by joint segregation analysis was examined. The inheritance of Rf genes in the two progenies was controlled by two major additive-dominant epistatic genes and additive-dominant epistasis polygene. The two major genes had high additive effects and dominant effects. In addition, there existed significant epistatic effects between the two major genes. The major genes had high heritability in F2, BC1, and BC2 generations. Also, the fertility restorer characteristic can be selected during early generations of the breeding cycle.
Jian-Feng Geng, Cheng-Song Zhu, Xiao-Wei Zhang, Yan Cheng, Yuan-Ming Zhang, and Xi-Lin Hou
Brassica rapa L. ssp. chinensis (L.) Hanelt, known as nonheading chinese cabbage in China, is an important vegetable in eastern Asia and its genetic improvement requires a genetic linkage map. The first genetic linkage map of nonheading chinese cabbage using 112 doubled haploid lines derived from a released F1 hybrid cultivar Shulü between two lines SW-3 and Su-124 was constructed in this paper. One hundred thirty-eight molecular markers were mapped into 14 linkage groups. Among these markers, there were 77 sequence-related amplified polymorphism markers, 27 simple sequence repeat markers, 21 random amplification polymorphic DNA markers, and 13 intersimple sequence repeat markers. Chi-square tests showed that 54 markers are distorted from Mendelian segregation ratios, and the direction of the distortion is mainly toward the maternal parent SW-3. The distortion affects not only the estimation of genetic distance, but also the order of distorted markers on a same linkage group. Given a specific marker order, the authors proposed a multipoint approach to correct the linkage map in an unbiased manner in an F2 population while considering distorted, dominant, and missing markers. A new method was used to correct the linkage map in the doubled haploid population mentioned earlier considering new, distorted, and missing markers. The total length of the corrected linkage map was 1923.75 cM, with an average marker spacing of 15.52 cM. The map will facilitate selective breeding and mapping of quantitative trait loci.