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1

Synergistic roles of leaf boron and calcium during the growing season in affecting sugar and starch accumulation in ripening apple fruit

100%

Lu Y. Q. , Liu H. P. , Wang Y. , Zhang X. Z. , Han Z. H.

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nr 08

EN

Fruit sugar content is one of the most important flavor quality traits in the fresh market. Minerals, such as boron (B) and calcium (Ca), are associated with fruit sugar and starch accumulation in many plant species. To better understand the roles of B and Ca in affecting sugar and starch accumulation in apples, 2 g L-1 Na2B4O710H2O or 10 g L-1 CaCl2 was supplied by foliar spray to 20-year-old ‘Fuji’ (Malus domestica Borkh. cv. Fuji) trees at four developmental stages (fruit set, onset of rapid fruit growth, rapid fruit growth and the end of rapid fruit growth), in 2010–2011. The most effective treatment significantly increasing soluble sugar and starch levels in ripening fruit was the foliar application of 2 g L-1 Na2B4O710H2O during rapid fruit growth, and the robustness of the effects was confirmed for two cultivars, ‘Fuji’ and ‘Orin’, at three orchards in 2011. Foliar applications of B during the onset of rapid fruit growth and rapid fruit growth, as well as the foliar application of Ca at fruit set, significantly increased the soluble sugar content in ripening fruit. In addition, the B application was effective in increasing the fruit starch content, but Ca was not. Both B and Ca treatments significantly increased the leaf concentrations of the other element at least transiently. However, B and Ca effects on fruit sugar/ starch did not seem to depend on higher leaf B or Ca levels. In conclusion, B and Ca interact in enhancing fruit sugar and starch contents at the fruit ripening stage.

2

Low expression of PIN gene family members is involved in triggering the dwarfing effect in M9 interstem but not in M9 rootstock apple trees

100%

Zhang H. , An H. S. , Wang Y. , Zhang X. Z. , Han Z. H.

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tom 37

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nr 05

EN

In many perennial woody crops, true-to-type scion is propagated via grafting techniques. The vigour of apple trees can be reduced by grafting on to dwarfing rootstock like M9. However, the mechanisms as to how rootstocks induce dwarfing on their scion remain unclear. Here, members of the gene families encoding auxin polar transporters, PIN and LAX, were analysed in M9, Fuji, and Baleng Crab. Of the 13 members, MdPIN8, MdPIN10 and MdPIN13 were preferentially and differently expressed in the scion, interstem or rootstock in grafting complexes. The dynamic changes in phytohormone contents, relative expressions of MdPINs, and shoot growth after 1-naphthaleneacetic acid (NAA), 6-benzylaminopurine (BA) or N-1- naphthylphthalamic acid (NPA) treatments were evaluated in 3-year-old Fuji/M9, Fuji/M9/Baleng Crab and Fuji/Baleng Crab. In Fuji/M9, foliar or root application of NAA increased root auxin (NAA + IAA) levels but did not significantly increase root zeatin content or shoot growth. Leaf cytokinin (zeatin + BA) levels and shoot growth increased significantly after foliar or root application of BA. In Fuji/M9/Baleng Crab, root application of NAA induced a significant increase in root and leaf zeatin contents and shoot growth, but NAA foliar sprays did not, because the expression of MdPIN8 in the bark of interstem M9 did not increase. When stem auxin transport was inhibited by NPA in Fuji/Baleng Crab, root zeatin level and shoot growth declined dramatically. It was proposed that the dwarfing effect was initiated by inherently lower expression of MdPIN8 in M9 interstem, or by poor root zeatin synthesis in M9.

3

Raduced late-season leaf potassium and phosphorus levels influence decreases in sugar contents of bagged apple fruit

86%

Zhu B. , Lu Y. Q. , Zhang X. Z. , Wang Y. , Liu H. P. , Han Z. H.

Acta Physiologiae Plantarum

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2014

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tom 36

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nr 06

EN

Fruit bagging has been widely used in the fruit production industry; however, in apples, it is known to cause a significant decrease in fruit sugar contents. To address this issue and identify the changes in leaf mineral contents associated with fruit sugar levels in bagged apples, aqueous solutions of 10 g L⁻¹ CaCl₂,5gL⁻¹ KH₂PO₄, or 2gL⁻¹ Na₂B₄O₇‧10H₂O were foliar sprayed during four fruit developmental stages. The late-season leaf phosphorus (P) and potassium (K) contents after the rapid fruit growth period and the soluble sugar contents in ripening fruit were significantly lower in bagged fruit than in nonbagged fruit (11.1–15.09 %). The decreases in leaf P and K contents caused by bagging were almost completely compensated for by foliage applications of CaCl₂, KH₂PO₄, or Na₂B₄O₇ during the fruit set period. Therefore, the fruit soluble sugar contents were significantly higher in bagged ripening fruit with foliar spray than in bagged fruit without foliar sprays, reaching the levels of non-bagged apples. The decrease in the sugar contents of bagged apples was closely associated with the decrease in late-season leaf P and K levels caused by fruit bagging.

4

Impact of Extra Nitrogen on Ecological Stoichiometry of Alpine Grasslands on Tibetan Plateau : Meta-Analysis

72%

Zhang H. R. , Sun W. , Li S. W. , Han F. S. , Yu C. Q. , Zhang X. Z. , Wang J. S. , He Y. T. , Zhong Z. M.

Polish Journal of Ecology

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2018

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tom Vol. 66, nr 4

315--324

EN

The general impact of extra nitrogen on ecological stoichiometry was examined in alpine grasslands on the Tibetan Plateau. Extra nitrogen increased the ratio of nitrogen to phosphorus (N:P ratio) in leaves and aboveground parts of plants by 43.4% and 32.7%, respectively. In contrast, extra nitrogen reduced the ratio of carbon to nitrogen (C:N ratio) in leaves by 30.6%. Extra nitrogen decreased soil C:N ratio by 9.1% in alpine meadows, but increased soil C:N ratio by 3.4% in alpine steppes. Extra urea had a stronger positive impact on aboveground vegetation N:P ratio than did extra ammonium nitrate. Extra urea rather than ammonium nitrate decreased aboveground vegetation C:N ratio and soil C:N ratio. The impact of extra nitrogen on aboveground vegetation N:P ratio was positively correlated with latitude, mean annual temperature and precipitation, nitrogen application rate and accumulated amount, but negatively correlated with elevation, duration and aboveground vegetation N:P ratio of the control plots. The impact of extra nitrogen on leaves N:P ratio was positively correlated with nitrogen application rate and accumulated amount. The impact of extra nitrogen on leaves C:N ratio was positively correlated with latitude, but negatively correlated with mean annual temperature and precipitation, nitrogen application rate, accumulated amount, duration and leaves C:N ratio of the control plots. Therefore, nitrogen enrichment caused by human activities will most likely alter element balance and alpine plants from nitrogen limitation to phosphorus limitation. This effect may weaken with time, and increase with climatic warming, increased precipitation and nitrogen input rate.