Stability of soil organic carbon changes in successive rotations of Chinese fir(Cunninghamia lanceolata(Lamb.) Hook) plantations

The importance of soil organic carbon （SOC） under forests in the global carbon cycle depends on the stability of the soil carbon and its availability to soil microbial biomass. We investigated the effects of successive rotations of Chinese fir （Cunninghamia lanceolata （Lamb.） Hook） plantations on the stability of SOC and its availability to microbes by adopting the two-step hydrolysis with H2SO4 and density fractionation. The results showed that successive rotations of Chinese fir decreased the quantity of total SOC, recalcitrant fraction, and carbohydrates in Labile Pool I （LPI）, and microbial properties evidently, especially at 0-10 cm horizon. However, cellulose included in Labile Pool Ⅱ （LP Ⅱ） and the cellulose/total carbohydrates ratio increased in successive rotations of Chinese fir. The noncellulose of carbohydrates included in LPI maybe highly available to soil microbial biomass. Hence the availability of SOC to microbial biomass declined over the successive rotations. Although there was no significant change in recalcitrance of SOC over the successive rotations of Chinese fir, the percentage of heavy fraction to total SOC increased, suggesting that the degree of physical protection for SOC increased and SOC became more stable over the successive rotations. The degradation of SOC quality in successive rotation soils may be attributed to worse environmental conditions resulted from disturbance that related to ＂slash and burn＂ site preparation. Being highly correlated with soil microbial properties, the cellulose/total carbohydrates ratio as an effective indicator of changes in availability of SOC to microbial biomass brought by management practices in forest soils.

Combination of salicylic acid and ultrasonication for alleviating chilling injury symptoms of longkong

Objectives Chilling injury is a prominent physiological disorder in longkong fruit pericarp when stored under 13℃for a prolonged period.This study aimed to investigate the effects of individual salicylic acid(SA)and ultrasonication(US)treatments and of the combination salicylic acid and ultrasonication(SA-US)on alleviating the chilling injury symptoms in longkong fruit pericarp when in prolonged cold storage.Materials and Methods SA(1 mmol/L)and US(40 kHz,10 min at 90%amplitude,350 W)were used as individual and combined(SA-US)treat-ments to control the chilling injury in longkong pericarp.The various quality measures were checked every 2 d in longkong for up to 18 d of cold storage(13℃,90%relative humidity).Results The results revealed that the control fruits treated with water exhibited severe chilling injury symptoms followed in rank order by US,SA,and SA-US cases.Treatments such as US and SA alone were more effective in controlling chilling injuries than control,while only minimal signifi-cant differences were noticed between them.On the other hand,the longkong pericarp treated with the SA-US combination had significantly increased antioxidant enzyme(superoxide dismutase and catalase)activities and decreased levels of membrane lytic(phospholipase D and lipoxygenase)enzymes and browning-inducing enzymes(phenylalanine ammonia lyase and polyphenol oxidase).Consequently,in the longkong pericarp,the chilling injury index,electrolytic leakage,respiration rate,weight loss,firmness,malondialdehyde content,changes in unsaturated and saturated fatty acid contents,and reactive oxygen species were significantly controlled by this treatment.Conclusions The present study concludes that longkong fruit treatment with a combination of US and SA is an excellent alternative for control-ling the chilling injury symptoms and extending the shelf-life.

Effect of drying technologies on the biochemical properties of Stolephorus commersonnii

Objectives:Two different methods,namely traditional sundrying and solar dryer drying were employed to investigate the effect of drying method on the quality of Indian anchovies,Stolephorus commersonnii.Materials and Methods:Fifty fish samples of Stolephorus commersonnii were purchased for the drying study.Traditionally dried fishes were bought from the local market.For solar drying the samples were kept in on the solar cabinet dryer KSD 25 designed and fabricated by the Central Institute of Fisheries Technology(CIFT).International standard AOAC methods were used for quality analysis of dried fish samples.Results:The method of drying by the solar dryer is more hygienic and faster than the traditional sun-drying method.The biochemical compositions and sensory evaluation of the products obtained showed significant variation between the two drying methods.Solar dryer-dried fish has got good organoleptic score than the traditional sundried fish.The overall quality of fish dried in the solar dryer was better than the traditionally sundried fish.Conclusions:The study clearly indicates that solar drying can be used as an environment-friendly method for fish processing which enhances food security.