An Optimal Combination of the Propagation Medium and Fogging Duration Enhances the Survival, Rooting and Early Growth of Strawberry Daughter Plants

Runner propagation is an important process in strawberry cultivation, which influences plant survival and fruit yield during the commercial production. In South Korea, this process is carried out on plug tray benches that are set off the ground in greenhouses, rather than in open fields. During the propagation, the propagation media and fogging systems play an important role in the survival and rooting of daughter plants. The aim of this study is to investigate the influences of the different types of propagation media and various fogging treatments on the rooting and early growth of strawberry daughter plants. Two strawberry cultivars—‘Maehyang’ and ‘Seolhyang’—in a glasshouse, grown in four different propagation media-a peat moss-based mixture (PBM), rockwool cube (RWC), granular rockwool (GRW), and a coir-based mixture (CBM)—combined with five fogging durations, 0, 3, 6, 9 and 12 days were tested. PBM with 9–12 days of fogging was the most ideal combination for the rooting and early growth of daughter plants of the two strawberry cultivars, which increased the ratio of survival and rooting, number of new leaves, root length and maximised the fresh and dry weights of the aboveground and belowground runner biomass. However, fogging treatments shorter than 9 days led to a lower survival rate and rooting. RWC and GRW are not recommended for young plants of these two strawberry cultivars because their strong water-retentive properties could subject the root to water stress, which can lead to root rotting. The purpose of this study is to provide a reference for strawberry growers to improve the quality of plants and efficiency of production during the propagation period.

Probabilistic corrosion time initiation modelling in reinforced concrete structures using the BEM

The reinforcement’s depassivation in reinforced concrete structures occurs when the chloride concentration at the reinforcement’s interface reaches the threshold content. The depassivation phenomenon starts the propagation period, in which huge mechanical degradation processes are triggered. Moreover, it is well established that the propagation period is considerably shorter than the initiation period. Therefore, the accurate prediction of the corrosion time initiation is a major issue in structural durability domain. This study presents a transient formulation based on the Boundary Element Method (BEM) for the corrosion time initiation assessment. The diffusion fields evaluated by the BEM are utilized into a probabilistic framework, which enables the assessment of probabilistic values for corrosion time initiation. Therefore, the formulation handles properly the uncertainties in this problem, which is largely subjected to randomness. Three applications are presented. The robustness and accuracy of the proposed approach over classical analytical models are highlighted.

A real-time method to predict social media popularity

How to predict the future popularity of a message or video on online social media (OSM) has long been an attractive problem for researchers. Although many difficulties are still ahead, recent studies suggest that temporal and topological features of early adopters generally play a very important role. However, with the increase of the adopters, the feature space will grow explosively. How to select the most effective features is still an open issue. In this work, we investigate several feature extraction methods over the Twitter platform and find that most predictive power concentrates on the second half of the propagation period, and that not only a model trained on one platform generalizes well to others as previous works observed, but also a model trained on one dataset performs well on predicting the popularity for other datasets with different number of observed early adopters. According to these findings, at least for the best features by far, the data used to extract features can be halved without loss of evident accuracy and we provide a way to roughly predict the growth trend of a social-media item in real-time.

Statistical Distributions for the Corrosion Rates of Conventional and Prestressing Steel Reinforcement Embedded in Chloride Contaminated Mortar

Many concrete structures are built using plain mild (PM) and cold-twisted deformed (CTD) steel rebars. Also, quenched and self-tempered (QST) and prestressing (PS) steels are extensively used in today’s construction. For estimating the corrosion propagation period (tp) of concrete structures, the current practice is to assume that the corrosion rate (icorr) of different steels are equal to that of PM steel—leading to erroneous estimation of tp. This paper provides icorr data from a 33-month experiment on PM, CTD, QST, and PS steels embedded in chloride contaminated mortar. Linear polarization resistance test was adopted for icorr measurement. A total of 100 specimens were tested. It was found that the CTD and QST steels exhibit higher icorr than the PM and PS steels. The paper also provides statistical distributions for icorr of these four steels. For PM, CTD, QST, and PS steel embedded in chloride contaminated mortar, and exposed to wet-dry conditions, these are found to be ∼Weibull (2.5, 20.7, 0) μA/cm2, ∼Lognormal (0.45, 3.2, 0) μA/cm2, ∼Gamma (6.8, 3.5, 0) μA/cm2, and ∼Weibull 3P (1.3, 6.5, −0.02) μA/cm2, respectively. Similar distributions for dry condition are also presented. These statistical tools would help engineers in estimating residual service life and scheduling repair activities.

Surveying Changes in Sectional Tissue Nutrient Concentrations of Hibiscus acetosella ‘Panama Red’ during Adventitious Root Formation

A study was conducted to observe changes in mineral element concentrations within different sections of leafy stem cuttings of Hibiscus acetosella ‘Panama Red’ (PP20121) during a 21-day propagation period under standard industry propagation conditions. Concentrations of 13 mineral elements were analyzed in leaves, lower stems (below substrate), upper stems (above substrate), and roots at 3-day intervals. Before root emergence (day 0–6), P, K, Zn, Ca, and Mg concentrations decreased in the shoots (including upper stems and leaves), whereas Zn, Ca, and B concentrations decreased in the lower stems. Sulfur increase occurred in lower stems before root emergence. After rooting (day 9–21), N, P, Zn, Fe, Cu, and Ni concentrations decreased in the roots; K, S, B, and Mg concentrations increased. In the lower stems, N, P, K, S, and Zn concentrations decreased, whereas B increased. Potassium concentration decreased in the leaves; P, K, S, and Zn decreased in the upper stems. Calcium and Mg increased in leaves. This study indicates specific nutrients are important in adventitious rooting, and that it is important to analyze rooting as a function of fine-scale temporal measurements and fine-scale sectional measurements.