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Richard L. Hassell, Robert J. Dufault and Tyron L. Phillips

Ten triploid and 25 diploid watermelon (Citrullus lanatus) selections were evaluated to determine the temperature range and length of test for which germination index (rate of germination over time) and germination percentages were maximum for expediting vigor and seed testing practices. Temperature interacted with watermelon selection indicating that certain selections germinated faster within specific, but differing temperature ranges. Within 2 days after starting the germination process, 90% of triploid selections and 96% of diploid selections germinated to their greatest level and prolonging germination data collection for one week did not change this relationship. Although optimal temperature ranges may differ among the selections, the one temperature within the range common for all selections evaluated that maximized germination was 85 to 90 °F (29.4 to 32.2 °C) for diploids and 85 °F for triploids.

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YanLing Zheng, GaoJuan Zhao and HuanCheng Ma

because of the slow metabolic rate of seeds. Fig. 1. The effect of desiccation on germination percentage (GP), germination index (GI), seedling fresh weight (SFW), and vigor index (VI) of dark-brown mature seeds (collected from split fruit in 2013) of

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Haiyan Zhang

the rate of germinated seeds on the 20th day. Germination index was GI = Σ(Gt/Tt), where Gt is the number of germinated seeds in Day t and Tt is the time corresponding to Gt in days. Vigor index was VI = GI × shoot height on the 25th day. MGT was

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Haiyan Zhang

. Germination index (GI), vigor index (VI), germination velocity (GV), and mean germination time (MGT) of C. bungei seeds at different concentrations of sodium nitroprusside (SNP) under 60 m m NaCl. Table 3. Shoot height (SH), taproot length (TL), shoot

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Monica Ozores-Hampton, Thomas A. Bewick, Peter Stoffella, Daniel J. Cantliffe and Thomas A. Obreza

The influence of compost (derived from MSW and biosolids) maturity on seed germination of several weed species was evaluated. A bioassay was developed by extracting 20 g of compost of different maturities with various volumes of water, then measuring germination percentage of ivyleaf morningglory (Ipomoea hederacea) seeds placed on extract-saturated filter paper in a petri dish. A 20 g (dry weight) compost: 50 mL of water generated an extract that produced the widest percentage seed germination variation in response to composts of different maturity. Ivyleaf morningglory, barnyardgrass (Echinochloa crus-galli L.), purslane (Potulaca oleracea L.), and corn (Zea mays L) were selected as plant indicators to determine the compost maturity stage with maximum germination inhibition. Compost 8-week-old decreased percent germination, root growth, and germination index (combines germination rate and root growth), and increased mean days to germination (MDG) of each plant indicator. Immature 8 week-old compost extract effect on MDG and germination percent of 15 weed species was evaluated. Extract from 8-week-old compost inhibited germination in most weed species, except yellow nutsedge (Cyperus esculentus). Compost extracts derided from immature (3-day, 4-, and 8-week-old) compost resulted in delayed and reduced germination percent of important economic weed species.

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Leticia Santos-Hernández, Martha Martínez-García, Jorge E. Campos and Ernesto Aguirre-León

The orchid Laelia albida is an important cultural and religious plant resource of the Tehuacan-Cuicatlan Valley Biosphere Reserve in south-central Mexico. It is gradually becoming scarce due to overcollecting and habitat perturbation. For this reason, and for preservation purposes, the aim of the present work was to obtain the conditions to successfully propagate this species, through the use of mature seeds stored at 4 °C, and basal buds following in vitro techniques. Seeds with different storage periods (lot 1 and lot 2) were analyzed for seed viability as determined by the TTC method, germination percentage and germination index were analyzed on a monthly basis for 11 months on two Knudson C (K-4003, K-4128; Sigma). Seedlings were initially grown on the same culture media variants, but 30 days later they needed to be supplemented with potato starch (20 g·L-1). Basal buds were cultured on Knudson C containing nine BAP and NAA combinations two of which were also supplemented with potato starch (20 g·L-1) and coconut water (10%). Seed viability ranged from 78% to 98% throughout the 11 months and germination percentage was 70% to 90% without significant differences between the two lots. K-4003, either alone or supplemented with potato starch, was the best culture medium used to achieve all the development stages as well as seedlings with rhizoids. Bud proliferation was also successful on K-4003 added with BAP, NAA, potato starch and coconut water. The BAP (7.4 μm) and NAA (5.3 μm) combination promoted shoots and protocorm-like bodies (PLB). The results obtained with basal buds, make its preservation through in vitro culture possible and give the possibility to obtain available plantlets for its cultivation in regional nurseries. Storage conditions tested here may be useful for seed bank management for this species. Chemical names used: 6-benzylaminopurine (BAP), 1-naphthaleneacetic acid (NAA).

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Xu-Wen Jiang, Cheng-Ran Zhang, Wei-Hua Wang, Guang-Hai Xu and Hai-Yan Zhang

percentage was determined on day 14. Germination index, vigor index, germination velocity, and mean germination time were calculated according to the reported method ( Hu et al., 2005 ; Timson, 1965 ; Zhang, 2015 ). On day 20, shoot height, root length, and

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Clíssia Barboza da Silva, Julio Marcos-Filho, Pablo Jourdan and Mark A. Bennett

the paper weight, and then placed at bottom of plastic boxes (28.5 × 18.5 × 10.0 cm) under alternating temperature of 20–30 °C. The number of normal seedlings was recorded daily to obtain speed of germination indexes ( Maguire, 1962 ). Germination

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Yan-Ling Zheng and Huan-Cheng Ma

germination index (GI) indicating germination rate were determined. GI was calculated according to Zheng and Sunday (2008) : GI = ∑(G t /D t ), where G t is the number of seeds germinating on the t th day of incubation and D t is number of days of seed

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Federica Larcher and Valentina Scariot

number of germinated seeds and measuring the length of the radicles. The responses were calculated after 24, 48, and 72 h by a germination index (GI) according to the following formula ( Zucconi et al., 1981 ): GI (% of the control)= (Gs * RLs)/(Gc * RLc