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Kappaphycus alvarezii sap (K-sap) facilitates plant growth in stressful environments by regulating the stress signalling components of the plant system. In the present study, the effect of K-sap on three durum wheat varieties, commercially important for pasta and semolina is studied in response to salt and drought stress during both vegetative and reproductive growth phases. The application of K-sap contributed to the improvement of the morphological, physio-biochemical parameters and gene expression facilitating improved growth and yield. Under salt stress, K-sap-treated plants maintained lower Na+/K+ ratio and higher Ca2+ content. During stress, K-sap reduced cell membrane damage by maintaining higher tissue water content, reduced electrolyte leakage and reduced malondialdehyde contents. Reactive oxygen species, superoxide and peroxide contents were also significantly reduced on K-sap treatment. Osmoprotectants such as total proteins, proline, amino acids and soluble sugars increased with K-sap application both with and without stress. The phytohormones abscisic acid, cytokinin and auxin were significantly regulated by K-sap application. qPCR analysis showed enhanced expression of stress-responsive wheat MAP kinase, WRKY transcription factor and antioxidative genes with K-sap treatment during stress. The application of K-sap significantly improved yield by increasing number of spikes and grains. Here, we report for the first time the integrative study of metabolic components coordinated by genes and hormones to reveal the mechanism of K-sap in durum wheat for improving yield and stress tolerance.

The red algae species Kappaphycus alvarezii holds significant potential to evolve into a multimillion-dollar industry in the Solomon Islands. However, production levels have remained stagnant over the past decade. This study hypothesizes that technical inefficiencies at the farm level are a major factor limiting the industry's growth. Specifically, we examined the relationships between farm characteristics, resource use, and production efficiency in Wagina, an island with high cultivation potential. We selected 78 farmers for the survey via a structured questionnaire. Technical efficiency (TE) was assessed using Stochastic Frontier Analysis (SFA) conducted in R software. Results revealed mean TE values of 0.362 for small-scale and 0.535 for medium-scale production systems, suggesting substantial inefficiencies in resource utilization. Notably, the number of plots, the number of lines, and seed density per line were positively associated with TE, while education level and farmers’ age were negatively correlated. The results suggest that improving farm structures and optimizing resource allocation could enhance production efficiency. Addressing the factors that negatively influence TE may help unlock the industry’s full potential.

Sustainable intensification of agricultural productivity is a global challenge. The sap of the commercially important red seaweed, Kappaphycus alvarezii, has been of interest in this regard, and its application as foliar spray has had a profound impact on the yields of many crops. It has been shown to contain indole acetic acid, kinetin, zeatin and gibberellic acid (GA₃) but no study is yet reported on the interactions among these constituents, if any. In the present study, selective solvent extraction was undertaken to obtain GA₃-free and indole acetic acid-free sap compositions. Another composition was prepared by autoclaving the sap which resulted in degradation of all the above growth hormones. The sap variants, along with water spray (control) and pristine sap, were applied on Zea mays as foliar spray over three consecutive seasons in dilute form. The four sap treatments were at par with one another—and significantly superior to control treatment—in so far as grain yield and quality were concerned. Pristine sap was subsequently shown to also contain choline and glycine betaine, and these were detected in similar amounts in all the sap variants, apparently indicating their profound influence on grain yield. Another important observation was that GA₃-free sap led to heightened photosynthetic activity which translated into 26 % increase in corn stover yield compared to pristine sap. This is hypothesized to be on account of prevention of negative interactions between GA₃and other hormones. The study constitutes the first report of enhancement of performance of a natural seaweed plant stimulant towards increasing plant growth through simplification of its composition.

Background Kappaphycus are farmed in tropical countries as raw material for carrageenan, which is widely used in food industry. The sea area available for farming is one limiting factor in the production of seaweeds. Though cultivation is spreading into subtropical regions, the lower seawater temperature is an important problem encountered in subtropical regions for the farming of Kappaphycus . This research of physiological response to low temperature stress will be helpful for screening Kappaphycus strains for growth in a lower temperature environment. Results Responses of antioxidant systems and photosystem II (PSII) behaviors in Kappaphycus alvarezii and Kappaphycus striatum were evaluated during low temperature treatments (23, 20, 17 °C). Compared with the controls at 26 °C, the H 2 O 2 concentrations increased in both species when the thalli were exposed to low temperatures (23, 20, 17 °C), but these increases were much greater in K. striatum than in K. alvarezii thalli, suggesting that K. striatum suffered more oxidative stress. The activities of some important antioxidant enzymes (e.g. superoxide dismutase and ascorbate peroxidase) and the hydroxyl free radical scavenging capacity were substantially higher at 23, 20 and 17 °C than at the control 26 °C in K. alvarezii , indicating that the antioxidant system of K. alvarezii enhanced its resistance to low temperature. However, no significant increases of antioxidant enzymes activities were observed at 20 and 17 °C in K. striatum . In addition, both the maximal efficiency of PSII photochemistry (F V /F m ) and the performance index (PI ABS ) decreased significantly in K. striatum at 23 °C, indicating that the photosynthetic apparatus was damaged at 23 °C. In contrast, no significant decreases of either F V /F m or PI ABS were observed in K. alvarezii at 23 °C. Conclusions It is concluded that K. alvarezii has greater tolerance to low temperature than K. striatum.

                                                                             AbstrakKappaphycus alvarezii merupakan salah satu rumput laut yang banyak diminta oleh pasar internasional, tetapi saat itu terjadi kegagalan budidaya akibat bakteri pathogen. Penelitian ini bertujuan untuk mengetahui kelompok bakteri apa yang menginfeksi rumput laut (Kappaphycus alvarezii). Penelitian ini dilakukan dengan kultur bakteri yang berasal dari thallus dan perairan pada media PCA, selanjutnya dilakukan pengujian angka lempeng total (ALT). ALT menunjukkan jumlah koloni bakteri yang mendominasi pada suatu media kultur. Hasil penelitian menunjukkan bahwa jumlah koloni bakteri yang berasal dari media perairan lebih tinggi dibanding yang berasal dari thallus Kappaphycus alvarezii                                                                                                                                                  AbstractKappaphycus alvarezii is widely demanding seaweed in the global market, although many farmers face crop failure which is caused by pathogenic bacteria. This research aims to investigate the group of infectious bacteria from Kappaphycus alvarezii seaweed. Bacteria isolated from thallus were cultivated on PCA medium, then the total plate count was determined. The total plate count demontrates the the number of colony dominated on the culture medium. This research showed that bacterium colony derived from aquatic medium is greater than from Kappaphycus alvarezii thallus.

Carrageenan is a polysaccharide derived from red algae (seaweed) with enormous economic potential in a wide range of industries, including pharmaceuticals, food, cosmetics, printing, and textiles. Carrageenan is primarily produced through aquaculture-based seaweed farming, with Eucheuma and Kappaphycus species accounting for more than 90% of global output. There are three major types of carrageenan found in red algae: kappa ( κ )-, iota ( ι )-, and lambda ( λ )-carrageenan. Kappaphycus alvarezii is the most common kappa-carrageenan source, and it is primarily farmed in Asian countries such as Indonesia, the Philippines, Vietnam, and Malaysia. Carrageenan extracted from K. alvarezii has recently received a lot of attention due to its economic potential in a wide range of applications. This review will discuss K. alvarezii carrageenan in terms of metabolic and physicochemical structure, extraction methods and factors affecting production yield, as well as current and future applications.

Kappaphycus alvarezii is one of the most important commercial sources of carrageenan. Red seaweeds are found in tropical areas, and K. alvarezii is famous for its high growth rate among other tropical red seaweeds. This study was conducted to produce Kapparazii powder super(TM), a product comprised of high amount of carrageenan with valuable nutrients from K. alvarezii found in Sabah, Malaysia. Spray drying and an environmentally friendly process without using chemicals were employed to produce Kapparazii powder super(TM). Physicochemical properties of Kapparazii powder super(TM) such as proximate composition (moisture, protein, lipid, ash, and crude fiber), mineral content, heavy metals, vitamins, amino acid, color, viscosity, gel strength, swelling capacity, and water and oil holding capacity were evaluated. Kapparazii powder super(TM) contained moisture (4.69 plus or minus 0.03 %), protein (5.11 plus or minus 0.02 %), lipid (1.00 plus or minus 0.02 %), ash (14.52 plus or minus 0.01 %), and crude fiber (0.93 plus or minus 0.02 %). Color analysis of Kapparazii powder super(TM) showed that lightness (L super(*)) = 89.51 plus or minus 0.02, redness (a super(*)) = -1.27 plus or minus 0.0 3, and yellowness (b super(*)) = 5.49 plus or minus 0.02. The value of viscosity, gel strength, swelling capacity, and water and oil holding capacity of the Kapparazii powder super(TM) were 0.06 plus or minus 0.00 Pa.s, 82.77 plus or minus 3.66 gf, 100 plus or minus 0.00 mL.g super(-1), 4.67 plus or minus 0.58 g.g super(-1), and 5.11 plus or minus 0.36 g.g super(-1), respectively. Moreover, Kapparazii powder super(TM) did not inhibit proliferation of L929 cells after 24 h of exposure at the highest concentration (2 mg.mL super(-1)). In conclusion, the Kapparazii powder super(TM) as a source of high nutrient hydrocolloid suggested on the point of healthy ingredient for food industry application.

This study aimed to analyze the optimal combination of temperature and light for the growth and quality of Kappaphycus alvarezii seaweed. This study used a factorial completely randomized design (CRD factorial) consisting of 2 factors (temperature and light) with three replications, which included a combination of temperature 28, 31, and 34 °C with light 50 and 100 photons (µmol m −2 s −1 ). The test object used was a seaweed seed weighing 50 g. The results showed that the S28C100 treatment gave the highest absolute weight growth value (P<0.05). The highest specific growth rate (SGR) was found in the S28C100 and S31C100 treatments, not significantly different between the two, respectively 3.77±0.058% and 3.03±0.12%. Treatment S31C50 followed by S31C100 gave the highest value for the carrageenan yield, but there was no significant difference between the two, respectively 15.505±0.71% and 13.965±0.26%. The combination of temperature and light in this study resulted in gel strength values of 922.150±234.26 to 1048.555±266.46 g.cm −2 but not significantly different between each treatment.

In this study, a simple, rapid, and eco-friendly green method was introduced to synthesize magnetite nanoparticles (Fe 3 O 4 -NPs) successfully. Seaweed Kappaphycus alvarezii ( K. alvarezii ) was employed as a green reducing and stabilizing agents. The synthesized Fe 3 O 4 -NPs were characterized with X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared (FT-IR), and transmission electron microscopy (TEM) techniques. The X-ray diffraction planes at (220), (311), (400), (422), (511), (440), and (533) were corresponding to the standard Fe 3 O 4 patterns, which showed the high purity and crystallinity of Fe 3 O 4 -NPs had been synthesized. Based on FT-IR analysis, two characteristic absorption peaks were observed at 556 and 423 cm −1 , which proved the existence of Fe 3 O 4 in the prepared nanoparticles. TEM image displayed the synthesized Fe 3 O 4 -NPs were mostly in spherical shape with an average size of 14.7 nm.

The eucheumatoids Kappaphycus and Eucheuma are cultivated in tropical or subtropical regions for the production of carrageenan, a hydrocolloid widely used in the food and cosmetic industries. Kappaphycus alvarezii is a highly valued economic crop in the Coral Triangle, with the Philippines, Indonesia and Malaysia ranked among the largest producers. In the absence of measures to mitigate climate change, extreme events including heatwaves, typhoons, severe El Niño and La Niña, are expected to increase in frequency and magnitude. This inadvertently brings adverse effects to the seaweed cultivation industry, especially in the tropics. Temperatures are rapidly reaching the upper limit of biologically tolerable levels and an increase in reports of ice-ice and pest outbreaks is attributable to these shifts of environmental parameters. Nevertheless, few reports on the response of eucheumatoids to a changing environment, in particular global warming, are available. Understanding the responses and possible mechanisms for acclimation to warming is crucial for a sustainable seaweed cultivation industry. Here, the physiological and biochemical responses of K. alvarezii to acute warming indicated that the strain used in the current study is unlikely to survive sudden increases in temperature above 36°C. As temperature increased, the growth rates, photosynthetic performance, phycocolloid quality (carrageenan yield, gel strength and gel viscosity) and pigment content (chlorophyll-a, carotenoid and phycobiliproteins) were reduced while the production of reactive oxygen species increased indicating the occurrence of stress in the seaweeds. This study provides a basis for future work on long term acclimation to elevated temperature and mesocosm-based multivariate studies to identify heat-tolerant strains for sustainable cultivation.