Variation Laws of Anthocyanin Content in Roots and Their Relationships with Major Economic Traits in Purple-Fleshed Sweetpotato Ipomoea batatas (L.) Lam

Variation laws of anthocyanin content in root during the development and among the varieties, and their relationships with major economic traits in purple-fleshed sweetpotato [Ipomoea batatas （L.） Lam] were studied in the present article. The dynamics of 20 economic traits in 13 purple-fleshed sweetpotato varieties at 20, 40, 60, 80, 100, 120, and 140 d after their transplanting were investigated, and these traits included anthocyanin content in root, length of the longest vine, number of base branches, root number, dry matter contents in stem, foliage and root, fresh/dry weight of root, fresh/dry weight of stem, flesh/dry weight of foliage, flesh/dry weight of stem and foliage, flesh/dry weight of whole plant, and rations of photosynthate to root, stem, and foliage. The correlations between the variations of anthocyanin content and the other 19 economic traits among varieties and during the whole developing stages, and the correlations of daily increase of anthocyanin content with other l0 kinds of yields were analyzed. The results showed that： （1） During the whole development, the anthocyanin content had three variation types, i.e. a slow-increase type, a fluctuating-change type, and a deviousrising type, and had different responses to the growth of length of the longest vine, number of base branches, flesh/dry yield of root, and photosynthate allotments. （2） The anthocyanin contents among 13 varieties began to have significant difference after 20 d, and showed completed differentiation during 40-100 d, which had significantly negative correlationships with the number of base branches, fresh/dry yield of root, photosynthate allotment ratio to root, and had significant positive correlationships with dry matter content of root, length of the longest vine, fresh/dry yield of stem, dry yield of whole plant and photosynthate allotment ratio to foliage. （3） Because of the significantly negative correlation between daily increase of anthocyanin content and dry matter weight of root, the anthocyanin accumulation competed with dry matter accumulation for photosynthate in root, and the competitive relation was resolved in different ways in different purple-fleshed sweetpotato （PFSP） varieties. So, there had three variation types of anthocyanin content among PFSP varieties during their development, and had different correlations between these variations of anthocyanin content and the major economic traits.

New Positioning of Forest in Green Development

In the 20 years after the UN Environment and Development Conference in 1992,the essential issues in relation to sustainable development have been unsolved.The upcoming "Rio + 20" conference put the focus on the shift towards green development. To achieve this requires the change of some ideologies that dominate human actions,such as the concepts of wealth,welfare and security,and it also require identifying the new position of nature resources, especially the position of forest.It was pointed out in the paper that forest is the foundation of socioeconomic development and constitutes basic wealth,basic welfare and basic security of the whole community under the green development context. Nevertheless,it is a must to aggressively invest and develop green economy.It was also proposed to set up forestry development organizations,investment mechanisms,policy system and research & education system compatible with green development. Moreover,some forestry policies that should be revised were combed.