Mineral composition in the holdfast of three brown algae of the genus Laminaria

SUMMARY: The mineral (Na, K, Ca, Mg, Fe, Mn and Zn) contents in the holdfast of three brown algae of the genus Laminaria were determined to compare with those in frond and stipe. The wild and cultivated kelps of Laminaria japonica , L. ochotensis , and L. diabolica were used as samples. The K content was markedly high (11.76–14.91 g/100 g dry weight) in the holdfast of cultivated L. japonica; the K/Na ratio (3.88–5.18) of the holdfast was greater than those of frond and stipe as well as the reported values of frond (1.0–2.2). The content of Ca in the holdfasts of these three species was also higher than those in frond and stipe. The content of Mn showed the same tendency. This is the first report showing that the holdfast of L. japonica and L. diabolica is rich in minerals, especially K.     

Effect of growth and parturition on hair cortisol in Holstein cattle

The effect of growth and parturition on hair cortisol concentrations of cattle was investigated. Plasma, saliva, and hair (black and white from the shoulders and hip) samples were collected from calves at 6 and 24 weeks old and from dairy cattle at the dry (1 and 2 months prepartum) and lactation (10, 50, 150, and 250 days postpartum) periods. Plasma and saliva cortisol concentrations were lower in 24-week-old calves than those of 6-week-old calves, and hair cortisol concentrations decreased regardless of color and position. In 6-week-old calves, hair cortisol concentrations differed between sampling positions, but this difference was not observed in 24-week-old calves. Plasma and saliva cortisol concentrations increased before parturition until 10 days postpartum then decreased until 50 days postpartum. The same trend was observed in the cortisol concentrations of white hair. Contrarily, cortisol concentrations in black hair remained unchanged and was lower than that in white hair. Hair cortisol concentration can vary greatly depending on the location on the body, hair color, cattle age, or parturition. When this method is used, all of the above factors must be considered.     

The production economics of freshwater prawn (Macrobrachium rosenbergii) farming in Hawaii

Detailed cost-return of freshwater prawn farming in Hawaii is estimated for farms ranging in size from a minimum of 1 acre to a maximum of 100 acres. Major factors affecting cost and revenue are discussed. Freshwater prawn farming in Hawaii is profitable at the existing average annual production of 3 000 pounds/acre and at the existing average farm price of $3.00/pound for farms that are 10 acres or larger. Smaller farms are profitable only when operated as a family venture.     

Can harvest outsourcing services reduce field harvest losses of rice in China?

The purpose of this study is to quantify the rice harvest losses in China and to evaluate the impacts of machinery and harvest outsourcing services on these losses, given the background of high-speed mechanization and outsourcing services. Data were collected from a national survey conducted in 2016 by the research team in conjunction with the Research Center for the Rural Economy of the Ministry of Agriculture and Rural Affairs of China. A non-parametric method was used to test whether combine harvesting and outsourcing services could significantly reduce harvest losses. Next, quantile regression was used to estimate the real effects of machinery and outsourcing services on harvest losses. The analysis yielded four main study outcomes. First, the harvest loss rate of rice in China was 3.65%. Second, mechanical reaping and winnowing caused greater losses than manual methods, while the opposite was true of field transportation. Third, combine harvesting increased the losses. Fourth, the effects of an outsourcing service on losses differed among the different harvesting methods. Outsourcing services increased losses in segmented harvesting but they reduced losses in combine harvesting.     

Effect of nitrogen fertilization on methane flux in a structured clay soil cultivated with onion in Central Hokkaido,Japan

Abstract

This study was conducted to investigate the effect of N fertilization on the soil CH₄ flux during the growing season of onion in a structured clay soil with stagnant water at depths of 70–80 cm and with a peat-mixed subsoil. The following 4 treatments were analyzed over a period of two years: T1) fertilized, onion growing, T2) fertilized, bare field, T3) unfertilized, onion growing, and T4) unfertilized, bare field. In the fertilized T1 and T2 treatments, fertilizers (mixture of 3 : 1 NH₄NO₃ : (NH₄)₂SO₄) at rates of 322 kg N ha^?1 in 1999 and 242 kg N ha^?1 in 2000 were applied as basal fertilizers before onion was transplanted. CH₄ fluxes among the treatments ranged from ?0.06 to 0.12 mg CH₄-C m^?2 h^?1 in 1999, and from ?0.03 to 0.01 mg CH₄-C m^?2 h^?1 in 2000, which were high after heavy rain in summer. Cumulative CH₄ flux from May to November in the fertilized T1 and T2 treatments was 59 mg CH₄-C m^?2 for both treatments in 1999, and 3.2 and ?0.9 mg CH₄-C m^?2 in 2000, respectively. On the other hand, in the unfertilized T3 and T4 treatments, the cumulative CH₄ flux was 0.2 and ?9.2 mg CH₄-C m^?2 in 1999, and ?26 and ?20 mg CH₄-C m^?2 in 2000, respectively. Although the cumulative CH₄ flux in each treatment was higher in 1999 than in 2000, the fertilized treatments in both years showed a significantly higher cumulative CH₄ flux than the unfertilized treatments. This might be ascribed to the higher level of nitrification in the fertilized treatments, because a high nitrate concentration was observed in the fertilized treatments in the onion growing season. The results also revealed that onion growing did not exert a significant influence on the CH₄ flux. The precipitation from May to November was 642 mm in 1999 and 1,008 mm in 2000, and the CH₄ emission increased when the precipitation was low. In addition, the CH₄ concentration in the soil profile increased with the increase of the depth in summer as the soil was dry. These findings indicated that CH₄ diffusion from the soil to the atmosphere was inhibited by rainwater.     

Identification of quantitative trait loci associated with shoot sodium accumulation under low potassium conditions in rice plants

Sodium (Na) application has marked beneficial effects on plant growth when the potassium (K) supply is low. Under low K supply, three japonica rice (Oryza sativa L.) cultivars, Koshihikari, Nipponbare, and Sasanishiki, accumulated more Na than three indica cultivars, IR36, IR64, and Kasalath, and the effect of Na application on growth was greater in japonica Koshihikari plants than in indica IR64 plants. A quantitative trait locus (QTL) analysis using a population of backcross inbred lines derived from japonica Koshihikari and indica Kasalath identified two significant loci associated with shoot Na concentration on chromosomes 3 and 6. The quantitative trait locus for shoot Na accumulation on chromosome 6 was confirmed in a population of chromosome segment substitution lines. The major QTL detected in this study could be useful for increasing crop productivity under low K input.