分类: 生物学 >> 植物学 提交时间: 2018-01-22
摘要: Bamboo species—the only herbal trees—have unique structural and physiological characteristics that differ from those of other tree taxa. However, the role of night-time water use in bamboo is poorly understood and has rarely been investigated. We studied day- and night-time sap flow response to culm age and rhizome structure in three age levels (juvenile, mature, and senescent) of Phyllostachys pubescens growing in the Nankun Mountain Natural Reserve, South China. We found that sap flow density and whole-tree hydraulic conductance decreased with culm age. After cutting, day-time sap flow and night-time water recharge decreased obviously. In addition, night-time water recharge accounted for the largest proportion (up to 30%) of total daily transpiration in senescent normal bamboos. Therefore, our study indicates that the connected rhizome system and night-time water recharge played significant roles in water compensation during the day and at night in bamboos. Night-time water recharge is especially critical to senescent bamboos because of their weaker transpiration due to the lower whole-tree hydraulic conductance and those are more dependent on night-time water recharge for fulfilling their whole-day water consumption needs.
分类: 生物学 >> 生态学 提交时间: 2018-01-10
摘要: The health risks associated with the consumption of rice may decrease if consumers use cooking practices which can reduce the concentrations of metal(loid)s and their bioaccessibility. The effects of cooking on the bioaccessibility of Cd and As in three contamination levels of rice were studied. The results indicated that cooking reduced bioaccessibility of Cd and As in rice. Cooking resulted in a significant increase in Cd and As concentrations in the residual fraction. Low volume cooking rice to dryness remove total Cd by about 10% for rice A and B, while middle or high volume water had no effect on Cd bioaccessibility in all rice types. In contrast, low volume cooking did not remove As, but a significant decrease was observed when cooking with middle or high volume water. This study provides information for a better understanding of more realistic estimation of metal(loid)s exposure from rice and the possible health risks.