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Plant cell wall structure integrity and associated tissue mechanical properties is one of key determinants for the perceived texture of plant-based foods. Carrots (Daucus carota) were used to investigate the effect of mineral supply of boron (B) and/or calcium (Ca), during plant growth, on the plant cell wall structure and mechanical properties of matured root tissues. Five commercial cultivars of carrots, Kuroda (orange), Dragon Purple, Kuttiger White, Yellow, and Nutri-Red, were cultivated under controlled glasshouse conditions over two seasons. Significant increases in the accumulation of B and Ca were found for all cultivars of carrots when additional B and Ca were included in the nutrient feeding solutions throughout the plant growth period. Elevated levels of B in carrot root tissue reduced the uptake of Ca and other mineral nutrients and enhanced plant cell wall structural integrity, its resistance to fracture, and the weight and size (both diameter and length) of carrots. Although higher amounts of Ca were accumulated in the plant materials, the additional supply of Ca did not have a significant effect on the mechanical properties of mature plant tissues or on the uptake of B by the plant. The results suggest that B cross-linking of pectin (rhamnogalacturonan II) has a greater influence on mature tissue mechanical properties than Ca cross-linking of pectin (homogalacturonan) when supplied during plant growth.

Guangdong province, as a large energy consumption province as well as a large economic province in China, is facing more and more severe pressure from reducing carbon emission. Reducing agricultural carbon emissions and developing agricultural carbon storage and carbon sequestration, will result in a brilliant future for Guangdong agriculture. In this paper, agricultural carbon emissions of Guangdong during 1991-2012 are quantitatively analyzed to discover its variation characteristics. An evident evolution law between Guangdong economic growth and agricultural carbon emissions is revealed. The evolution law showed "N" shaped curve rather than the typical inverted "U" shaped curve of EKC, and there is no indication when the inflection point will appear, which indicates that agricultural carbon pollution will be more serious with economic growth in Guangdong. Finally, some corresponding suggestions on the policy are put forward to reduce carbon emissions.