Temperature ranges for survival and growth of juvenile Saccharina sculpera (Laminariales, Phaeophyta) and applications for field cultivation

Saccharina sculpera is highly valued for human consumption and value-added products. However, natural resources of this kelp have decreased sharply and it is in danger of extinction. Resources recovery through cultivation is being trialed to enable the sustainable use of this species. In this study, the temperature range for survival and optimal growth of juvenile S. sculpera was identified and applied to field cultivation. This study investigated the survival and growth of juvenile S. sculpera under six temperatures (i.e., 5, 10, 15, 16, 18, and 20°C) and two light intensities (i.e., 20 and 40 μmol photons m-2 s-1) in an indoor culture experiment. In these experiments, the blade length decreased at 16°C under the both light intensities. The thalli died at 20°C and 20 μmol photons m-2 s-1, and at 18‒20°C and 40 μmol photons m-2 s-1. During the field cultivation, early growth of S. sculpera was highest at the 5 m depth and growth decreased as the water depth increased. When the initial rearing depth was maintained without adjustment throughout the cultivation period (from December to October), all the cultivated S. sculpera plants died during August and September. However, S. sculpera plants lowered from 5 to 15 m and grew to 90.8 ± 13.1 cm in July. The seawater temperature at 15 m depth was similar to the upper level of thermal tolerance demonstrated by juvenile S. sculpera in the indoor culture experiments (16°C or lower). The plants were subsequently lowered to 25 m depth in August, which eventually led to their maturation in October. The present study confirmed that improved growth rates and a delay in biomass loss can be achieved by adjusting the depth at which the seaweeds are grown during the cultivation period. These results will contribute to the establishment of sustainable cultivation systems for S. sculpera.

Extending the Cultivation Period of Undaria pinnatifida by Using Regional Strains with Phenotypic Differentiation along the Sanriku Coast in Northern Japan

The Sanriku district is one of the largest Undaria pinnatifida (Wakame) cultivation areas in Japan. However, the production has steadily declined in recent years due to the high retirement rate among fishers. Extending the cultivation period is a potential way to improve productivity by decentralizing the workforce through the production process. We aimed to investigate the phenotypic differentiation between regional strains of U. pinnatifida collected from Matsushima Bay (MAT) and Hirota Bay (HRT) in the Sanriku district through a cultivation trial to verify the application for the purpose of extending the cultivation period. The growth of MAT was better than that of HRT when the cultivation started earlier (i.e., 9 and 19 October 2014); in contrast, HRT outperformed MAT when the cultivation started later (6 November and 12 December 2014). The yield of MAT reached over the standard amount in the Sanriku district in February. On the other hand, the yield of HRT reached over this value in April. Furthermore, the photosynthetic performance and nutrient uptake rates differed between MAT and HRT, indicating that the differences may result in maturation characteristics. According to these results, the combined use of MAT and HRT would be a valuable strategy by which to extend the cultivation period.

Effect of Different Bag Opening Methods of Oyster Mushroom (Pleurotus ostreatus) on Growth Parameter, Yield and Benefit Cost Ratio

Oyster mushroom growers are generally confused about the scientific basis of the cultivation technology with regard to the best bag opening method after a spawn run. The present study was undertaken to find out the effect of four different methods of bag opening on yield, benefit cost ratio (BCR) and biological efficiency of oyster mushrooms during November, 2020 to March, 2021. The results indicated that treatment-2 (retaining the polythene bag for the entire cultivation period) exhibited significantly the highest yield (1644.61 g bed-1) followed by treatment-3 (opening top part of the polythene bag after spawn run) (1536.62 g bed-1), and treatment-1 (opening top and bottom part of the polythene bag (1468.82 g bed-1) and treatment-4 (complete removal of the polythene bag) (1111.19 g). The BCR was also found to be the highest (4.39) in treatment-2 followed by treatment-3 (4.09), treatment-1 (3.96) and treatment-4 (2.98). Retaining the polythene bag during the entire cultivation period was found to be the best method of cultivation with regard to biological efficiency (82.23%). Opening the top part of the polythene bag after the spawn run showed the biological efficiency of 76.83% which was followed by the treatment with opening the polythene bag from the top and bottom part of the bed (73.44%).The lowest biological efficiency (55.56%) was observed in the treatment in which the entire polythene bag was removed after a spawn run in darkroom. Mushroom growers may retain the polythene bag surrounding the mushroom bed during the entire cultivation period for better economic return.

Recapitulating the Angiogenic Switch in a Hydrogel-Based 3D In Vitro Tumor-Stroma Model

To ensure nutrient and oxygen supply, tumors beyond a size of 1–2 mm3 need a connection to the vascular system. Thus, tumor cells modify physiological tissue homeostasis by secreting inflammatory and angiogenic cytokines. This leads to the activation of the tumor microenvironment and the turning of the angiogenic switch, resulting in tumor vascularization and growth. To inhibit tumor growth by developing efficient anti-angiogenic therapies, an in depth understanding of the molecular mechanism initiating angiogenesis is essential. Yet so far, predominantly 2D cell cultures or animal models have been used to clarify the interactions within the tumor stroma, resulting in poor transferability of the data obtained to the in vivo situation. Consequently, there is an abundant need for complex, humanized, 3D models in vitro. We established a dextran-hydrogel-based 3D organotypic in vitro model containing microtumor spheroids, macrophages, neutrophils, fibroblasts and endothelial cells, allowing for the analysis of tumor–stroma interactions in a controlled and modifiable environment. During the cultivation period of 21 days, the microtumor spheroids in the model grew in size and endothelial cells formed elongated tubular structures resembling capillary vessels, that appeared to extend towards the tumor spheroids. The tubular structures exhibited complex bifurcations and expanded without adding external angiogenic factors such as VEGF to the culture. To allow high-throughput screening of therapeutic candidates, the 3D cell culture model was successfully miniaturized to a 96-well format, while still maintaining the same level of tumor spheroid growth and vascular sprouting. The quantification of VEGF in the conditioned medium of these cultures showed a continuous increase during the cultivation period, suggesting the contribution of endogenous VEGF to the induction of the angiogenic switch and vascular sprouting. Thus, this model is highly suitable as a testing platform for novel anticancer therapeutics targeting the tumor as well as the vascular compartment.

Effects of Temperature and Photoperiod on the Flower Potential in Everbearing Strawberry as Evaluated by Meristem Dissection

The growing interest in using everbearing (EB) strawberry cultivars to extend the cultivation period has faced some challenges. These include poor runner production due to its perpetual flowering nature; irregular flowering behavior and extended periods of high temperature have caused floral inhibition and reduced yield. As flowering is an interplay between temperature and photoperiod, it is important to investigate the effects of this interaction on the cultivation. Therefore, this study used meristem dissection as a tool to study the effect of temperature and photoperiod on meristem development. Tray plants of two EB strawberry cultivars ‘Florentina’ and ‘Favori’ were grown at 20 °C, 25 °C, and 30 °C under short day (SD) conditions, and subsequently at 20 °C under long day (LD) conditions. The meristem development was analysed every 6 weeks for a 15-week period in SD and for 14 weeks in LD conditions using meristem dissection. The plants showed similar flowering patterns to previously studied everbearing cultivars, which was qualitative LD plants at high temperatures and quantitative LD plants at lower temperatures. Our results show that meristem dissection can be used to determine the temperature and photoperiodic effect on meristem development, and for the occurrence of cropping peaks, and can therefore be used to decide the environmental input and to evaluate yield potential.

The effect of carbon dioxide on the production of potato minitubers under aeroponic cultivation

The paper presents data on the effect of additional top dressing of potato plants with CO2 at a concentration of 2500 ppm cultivated in aeroponic plants. It was found that the increased concentration of CO2 provides better development of plant shoots (128.6%) and the root system (120.1%) relative to the control: a larger yield (123.7%) with a larger fraction of minicubes is formed, and the number of plants capable of producing 1100-1600 g of minicubes during the cultivation period increases. Additional feeding of CO2 at a concentration of 2500 ppm leads to an increase in the mass of plants, which occurs not due to increased hydration of tissues, but due to the accumulation of dry substances.

Grain yield optimisation in the Plain of Reeds in the context of climate variability

ABSTRACT The Plain of Reeds is a large floodplain in the Mekong Delta, where natural disasters such as droughts, off-season rainfall and floods have dramatically increased, leading to declining in crop yields. The objective of this study was to evaluate the adverse impacts of climate factors (ICF) on grain yield of the main growing crops in the Plain of Reeds to define the suitable cultivation period (SCP) for rice-growing areas as an adaptation solution to minimise the adverse impacts of climate factors. To conduct this research, a crop model was applied to define the suitable cultivation periods based on simulating the grain yields of each rice-growing season. When the suitable cultivation periods were deployed, the grain yield of all simulated growing crops improved significantly compared to the current cultivation periods (baseline), which, for the main growing crops in the Plain of Reeds, are no longer suitable for the current weather conditions that have been deeply affected by climate variability in recent years.