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  • Author or Editor: Yang Liu x
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990 Capsicum annuum varieties were assessed at the seedling stage in greenhouse for their resistance to TMV(T), CMV(C) and anthracnose(A), and their mature (purple-red) fruits were analyzed for the content of dry matter(DM), vitamin C(VC) and capsaicin(CA). The data were eventually analyzed by means of correlation and path coefficient analysis. The result was as follows: the content of DM had little positive effect but significantly (P=O.O1) negative effect on the resistance to TWV, CMV and anthracnose, i.e. Pdt=0.0066, Pdc=(-0 .1364**), Pda=(-0.1881**); whereas the content of VC or CA respectively exerted positive effect, even significantly (P=0.01) positive effect, on the resistance to TMV, CMV and anthracnose, i.e. Pvt=0.0756**, Pvc=0.0093, Pva=0.2069** and Pct=0.2003**, Pcc=0.2300**, Pca=0.0091.

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Chrysopogon aciculatus (Retz.) Trin. is a perennial turfgrass for its low management and resistance. To develop simple sequence repeat (SSR) markers for C. aciculatus, we used four Roche 454 pyrosequencing, combined with the magnetic bead enrichment method FIASCO (fast isolation by amplified fragment length polymorphism of sequences containing repeats) to isolate from the C. aciculatus. A total of 66,198 raw sequencing reads were obtained with 4289 sequences (6.48%) were fit for primer pair design. One hundred microsatellite loci were selected to test the primer amplification efficiency in 20 accessions, and out of these, 11 loci were polymorphic. The amount of observed alleles ranged from three to six, with an average of 3.64. Nei’s genetic diversity values ranged from 0.085 to 0.493, with an average of 0.293. Shannon’s information index values ranged from 0.141 to 0.686, with an average of 0.428. Twenty accessions were clustered into three groups by unweighted pair-group method with arithmetic means (UPGMA). These SSR markers will provide an ideal marker system to assist with gene targeting, cultivar variety or species identification, and marker-assisted selection in C. aciculatus species.

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Pepper seedlings in 4- or 5-leaf stage were inoculated by spraying the mixture of spore suspension (approximate 1X106 spores/ml) of both Colletotrichum coccodes and C. capsici. They were then kept wet and incubated in greenhouse under 27-28C. Every plant was respectively examined and recorded for symptoms on leaves and stem on the 7th and 14th day after inoculation. Various varieties of pepper were finally compared in their disease indexes. 1,015 varieties of pepper were evaluated for their resistance to anthracnose. The results showed that 91 varieties (8.96%) were resistant, 174 (17.14%) tolerant, 582 (57.33%) susceptible and 168 (16.55%) highly susceptible. Some resistant varieties showed relative resistance to TMV and CMV as well.

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Drought stress is one of the most important abiotic stresses limiting plant growth, while high recuperative capacity of plants from drought damages is critical for plant survival in periods of drought stress and rewatering. The objective of our study was to determine physiological and growth factors in association with drought tolerance and recuperative capacity of cool-season kentucky bluegrass (Poa pratensis cv. Excursion II) and warm-season zoysigrass (Zoysia matrella cv. Diomand), which were grown in controlled environment chambers and maintained well watered (control) or subjected to drought stress and subsequently rewatering. Compared with kentucky bluegrass, zoysiagrass maintained higher leaf hydration level during drought stress, as shown by greater relative water content (RWC), improved osmotic adjustment (OA), increased leaf thickness, and more extensive root system at deeper soil layers. Turf quality (TQ) and photosynthesis recovered to a greater level and sooner in response to rewatering for zoysiagrass, compared with kentucky bluegrass, which could be due to more rapid reopening of stomata [higher stomatal conductance (g S)] and leaf rehydration (higher RWC). The aforementioned physiological factors associated with leaf dehydration tolerance during drought and rapid resumption in turf growth and photosynthesis in zoysiagrass could be useful traits for improving drought tolerance in turfgrasses.

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We reported previously that the preharvest treatment of broccoli microgreens with 10 mmol·L−1 calcium chloride (CaCl2) increased the yield and postharvest quality. The objective of this study was to investigate whether other calcium forms have the similar effect, in particular, after postharvest dip in calcium solution. Our results are as follows: 1) Preharvest spray without postharvest dip: Both 20 mmol·L−1 calcium lactate (Ca lactate) and calcium amino acid (Ca AA) chelate significantly improved broccoli microgreens quality and inhibited microbial populations as compared with the water-only control during storage at 5 °C for 21 days. However, they were less effective than 10 mmol·L−1 CaCl2. 2) Postharvest dip without preharvest spray: The microgreens sprayed with water-only control were dipped in 0, 25, 50, or 100 mmol·L−1 Ca lactate solution containing 100 μL·L−1 chlorine immediately after harvest. During storage at 5 °C for 14 days, 50 mmol·L−1 Ca lactate dip showed the highest overall quality and lowest tissue electrolyte leakage. 3) Preharvest spray and postharvest dip: Combined preharvest 10 mmol·L−1 CaCl2 spray and postharvest 50 mmol·L−1 Ca lactate dip resulted in better postharvest quality than individual pre- or postharvest calcium treatments. However, the preharvest 10 mmol·L−1 CaCl2 spray without postharvest dip displayed a best overall visual quality and longest storage life. Our data indicate that pre- and postharvest calcium treatments have positive effect on maintaining the microgreens quality and extending shelf life. However, current postharvest dip/spinning/drying method profoundly reduces the shelf life due to mechanical damages. Technologies to optimize microgreens wash are needed to provide ready-to-eat product. Alternatively, the wash step can be avoided when the microgreens are grown under controlled settings.

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Southern highbush blueberry (SHB, Vaccinium corymbosum L. interspecific hybrid) is the major species planted in Florida because of the low-chilling requirement and early ripening. The growth pattern and nitrogen (N) demand of SHB may differ from those of northern highbush blueberry (NHB, V. corymbosum L.). Thus, the effect of plant growth stage on N uptake and allocation was studied with containerized 1-year-old SHB grown in pine-bark amended soil. Five ‘Emerald’ plants were each treated with 6 g 10% 15N labeled (NH4)2SO4 at each of 12 dates over 2 years. In the first year, plants were treated once in late winter, four times during the growing season, and once in the fall. In the second year, treatment dates were based on phenological stages. After a 14-day chase period following each 15N treatment, plants were destructively harvested for dry weight (DW) measurements, atom% of 15N, and N content of each of the plant tissues. Total DW increased continuously from mid-May 2015 to Oct. 2015 and from Mar. 2016 to late Sept. 2016. From August to October of both years, external N demand was the greatest and plants absorbed more N during the 2-week chase period, about 0.53 g/plant in year 1 and 0.67 g/plant in year 2, than in chase periods earlier in the season. During March and April, N uptake was as low as 0.03 g/plant/2 weeks in year 1 and 0.21 g/plant/2 weeks in year 2. Nitrogen allocation to each of the tissues varied throughout the season. About half of the N derived from the applied fertilizer was allocated to leaves at all labeling times except the early bloom stage in 2016. These results suggest that young SHB plants absorb greater amounts of N during summer and early fall than in spring.

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Tuber production of calla lily (Zantedeschia elliottiana Spreng cv. Super Gold) was investigated using three size ranges (7-10, 4-7, and <4 mm shoot diameter) of in vitro plantlets acclimated in either pots or soil beds in a protected house. The shoots and tubers of large plantlets exhibited higher rates of dry-matter accumulation than did those of small plantlets. The diameter of tubers harvested from pots ranged from 0.67 to 4.1 cm with median values of 2.7, 2.1, and 1.9 cm for the plants derived from large, medium, and small plantlets, respectively. Plants grown in soil beds, regardless of size, produced larger tubers than did those grown in pots. Tubers >3 cm in diameter developed on 25% and 52% of plants grown in pots and soil beds, respectively. Our results suggest that improved calla lily production could be realized by using larger in vitro plantlets as the source material and growing them in soil beds in a protected house.

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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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