The feasibility of steel slag used as an iron fertilizer was studied in a pot experiment with corn. Slag alone or acidified slag was added to two Fe-deficient calcareous soils at different rates. Results showed that moderate rates (10 and 20 g kg-1) of slag or acidified slag substantially increased corn dry matter yield and Fe uptake. Application of steel slag increased the residual concentration of ammonium bicarbonate-diethylenetriamine pentaacetic acid (AB-DTPA) extractable Fe in the soils. The increase of extractable Fe was usually proportional to the application rate, and enhanced by the acidification of slag. Steel slag appeared to be a promising and inexpensive source of Fe to alleviate crop Fe chlorosis in Fe-deficient calcareous soils.
本研究利用开放式空气中CO2浓度增加（Free Air CO2 Enrichment,FACE）试验平台,研究CO2浓度升高200 μmol·mol^-1下,水稻灌浆早期籽粒大小、生长速率、可溶性碳水化合物和淀粉含量及蔗糖转化酶活性等在开花后20 d内的变化动态.结果表明,与对照相比,FACE处理加快了灌浆早期籽粒的发育进程,尤其加快了籽粒宽度达到最大的日程,籽粒大小和籽粒灌浆速率提前3 d达到最大值;成熟时籽粒的长宽积FACE下的比对照下的提高了4.5%,但粒重无差异;FACE下开花后2～5 d内籽粒中的还原糖和蔗糖的含量及细胞壁转化酶和细胞质转化酶的活性显著高于对照下的,但淀粉含量和可溶性酸性转化酶活性则无显著差异.从结果推论,FACE加速水稻灌浆前期籽粒生长发育与其花后早期颖果内蔗糖合成和转运水平之间可能存在内在联系.
To study the effects of growing rice （Oryza sativa L.） leaves under the treatment of the short-term elevated CO2 during the period of sink-source transition, several physiological processes such as dynamic changes in photosynthesis, photosynthate accumulation, enzyme activities （sucrose phosphate synthase （SPS）, and sucrose synthase （SS））, and their specific gene （spsl and RSusl） expressions in both mature and developing leaf were measured. Rice seedlings with fully expanded sixth leaf （marked as the source leaf, L6） were kept in elevated （700 μmol/mol） and ambient （350 mol/L） CO2 until the 7th leaf （marked as the sink leaf, L7） fully expanded. The results demonstrated that elevated CO2 significantly increased the rate of leaf elongation and biomass accumulation of L7 during the treatment without affecting the growth of L6. However, in both developing and mature leaves, net photosynthetic assimilation rate （A）, all kinds of photosynthate contents such as starch, sucrose and hexose, activities of SPS and SS and transcript levels of spsl and RSusl were significantly increased under elevated CO2 condition. Results suggested that the elevated CO2 had facilitated photosynthate assimilation, and increased photosynthate supplies from the source leaf to the sink leaf, which accelerated the growth and sink-source transition in new developing sink leaves. The mechanisms of SPS regulation by the elevated CO2 was also discussed.
Jun-Ying LiXing-Hua LiuQing-Sheng CaiHui GuShan-Shan ZhangYan-Yan WuChun-Jiao Wang
