Digital library

Observations made for one year on the seasonal changes in growth, reproduction and spore output of Gracilaria foliifem and Gracilariopsis sjoestedtii are given. These red algae occurred only a few months during the year in the area of study. Maximum growth of G. foliifera was during April and of G. sjoestedtii was during September and January-March. Tetrasporophytes were more abundant than carposporophytes in G. foliifera, whereas in G. sjoestedtii carposporophytes occurred more. Maximum outputs of tetraspores and carpospores were recorded on the tirst day, and the period of peak shedding of spores coincided with the peak growth period of these seaweeds. There was, however, no definite rhythm of diurnal spore output.

Maximum development of plants occurs in the intertidal region at Kilakarai, southeast mast of India, during March-April and Jan.-Feb. in (i. arcuara var. orcuara and from Nov. to Feb. in G. corticota var. cylindrica. Tetrasporic plants are abundant almost throughout the year in both algae. Peak shedding of spores occurs during the maximum growth period in G. orcuota var. arcuoro while seasonal variations are not observed in the discharge of spores in G. corricata var. cylindrica. Monthly output of tetraspores and carpospores varies from 43 19 28,291 and from 10 to 40,055 spores g ^-1 fr wt in G. arcuoro var. orcuaro and G. corricoro var. cylindrica respectively. There is no definite rhythm in diurnal output in these algae.

Aquaculture is an industry with the capacity for further growth that can sustainably feed an increasing human population. Sugar kelp (Saccharina latissima) is of particular interest for farmers as a fast-growing species that benefits ecosystems. However, as a new industry in the U.S., farmers interested in growing S. latissima lack data on growth dynamics. To address this gap, we calibrated a Dynamic Energy Budget (DEB) model to data from the literature and a 2-year growth experiment in Rhode Island (U.S.). Environmental variables forcing model dynamics included temperature, irradiance, dissolved inorganic carbon (DIC) concentration, and nitrate and ammonium concentration. The modeled final estimate for S. latissima blade length (cm) was reasonably accurate despite underestimation of early season growth. Carbon limited winter growth due to a low modeled specific relaxation rate (i.e. the light-dependent reactions of photosynthesis) for some model runs; other model runs displayed nitrogen limitation which occasionally led to length overestimation and underestimation due to the degree of interpolation necessary from the field data. The model usage, however, is restricted to S. latissima grown in an aquaculture setting because of assumptions made about tissue loss, summer growth patterns, and reproduction. The results indicate that our mechanistic model for S. latissima captures growth dynamics and blade length at the time of harvest, thus it could be used for spatial predictions of kelp aquaculture production across a range of environmental conditions. The model could be a particularly useful tool for further development of sustainable ocean food production systems in the U.S. involving seaweed.

The study was conducted at RTC-Korea-Philippines Vocational Training Center Davao, Buhisan, Tibungco, Davao City from March to May 2017 to determine the growth performance of carrots in terms of number of leaves and leaf stalks as supplied with different levels of Kappaphycus alvarezii drippings at 10 ml, 20 ml, and 30 ml per liter of water. Data were statistically analyzed through Randomized Complete Block Design (RCBD) with five (5) treatments replicated three (3) times. The treatments include pure water (T1), a nutrient solution of 10 ml of Kappaphycus alvarezii drippings per liter of water (T2), a 20 ml Kappaphycus alvarezii drippings per liter of water (T3), a 40 ml Kappaphycus alvarezii drippings per liter of water (T4), and a concentration of water and commercial organic foliar fertilizer (T5). Results showed that the application of Kappaphycus alvarezii drippings through subsurface drip irrigation improved the vegetative growth of carrot in terms of the leaf stalk and leaf count at 30, 37, and 45 days after sowing, under greenhouse structure.