不同前作对磷肥后效的影响

在小麦、毛苕、豌豆施用磷肥的土壤上,接连种植玉米和小麦,研究前3种作物施磷的后效。结果表明,不同前作施磷均有明显后效,其大小既和前作增产效果、由肥料中吸收的磷素多少有关,也和磷肥用量有关。前作增产效果大,吸磷多,肥料利用率高,后效减少;磷肥用量低而前作利用率较高时,后作利用率显著下降,反之亦然。尽管第二、三料作物的吸磷量和肥料的利用率因前作而异,但三料作物的总利用率却大致接近,以亩施4.5kg P_2O_5者最高。经过三料作物吸收,磷肥用量高者仍有明显后效,但用Olsen法测定,不同处理有效磷含量却无明显差别。     

SUMO-specific protease 3 aggravates CaPO4-induced mouse abdominal aortic aneurysm formation by promoting macrophage polarization

AIMTo investigate the role of SUMO-specific protease 3 (SENP3) in macrophage polarization and calcium phosphate (CaPO₄)-induced abdominal aortic aneurysm (AAA) formation in mice. METHODS（1） Bone marrow-derived monocytes (BMDMs) in Senp3^flox/flox (wild-type, WT) mice and Senp3^flox/flox; Lyz2-Cre (monocyte-specific SENP3 knockout, i.e. conditioned knockout, cKO) mice were isolated and induced for M1 and M2 polarization. The mRNA and protein expression level of SENP3 were detected by RT-qPCR, Western blot and immunocytofluorescence, and the differential distribution of M1/M2 BMDMs from WT and cKO mice was analyzed. （2） CaPO₄ was administrated to induce AAA model in 8~12-week-old male WT and cKO mice. The AAA incidence, survival rate and maximal aortic diameter were analyzed between the 2 groups. Aortic aneurysm tissues were collected for pathological analysis, and the expression levels of SENP3, interleukin-1β (IL-1β), tumor necrosis factor-α (TNFα), IL-6 and matrix metalloproteinases-9 (MMP-9) were measured by RT-qPCR and Western blot. Dihydroethidium staining in situ in frozen sections was used to analyze the production of reactive oxygen species (ROS). （3） To explore the potential mechanisms, Western blot and co-immunoprecipitation were used to verify the de-SUMO modification of mitogen-activated protein kinase kinase 7 (MKK7) induced by SENP3. Besides, BMDMs were transfected with Flag-MKK7 wild type (Flag-MKK7 WT) and SUMO-modified site K18 mutant (Flag-MKK7 K18R mutant), and then M1 polarization of the cells was induced. The protein levels of p-JNK and MMP-9 in the 2 groups were determined by Western blot. RESULTS(1) SENP3 expression was up-regulated in M1 polarized macrophages (P<0.01), but was down-regulated in M2 polarized macrophages (P<0.01). The expression of SENP3 was decreased during the transformation of M1 to M2 in the macrophages (P<0.01), but was significantly up-regulated during the opposite process (P<0.01). Besides, more M1 macrophages and less M2 macrophages after induction were observed in the BMDMs from cKO mice than those from WT mice. (2) SENP3 expression was up-regulated in AAA tissues (P<0.05). The AAA incidence of cKO mice was significantly reduced after CaPO₄ induction (P<0.01), the survival rate was significantly improved (P<0.05), and maximal aortic diameter was significantly reduced in cKO group (P<0.01). The levels of IL-1β, IL-6 and TNFα, and the production of ROS were significantly down-regulated (P<0.01), meanwhile MMP-9 expression was also down-regulated in cKO mice (P<0.05). (3) the SUMO2/3 modification of MKK7 was reduced during M1 polarization, and MKK7 interaction with SENP3 was enhanced. Significantly up-regulated protein level of p-JNK and MMP-9 were verified in the M1 macrophages transfected with Flag-MKK7 K18R mutant (P<0.05). CONCLUSION SENP3 activates the MAPK/JNK pathway via de-SUMOylation of MKK7, regulates the M1/M2 polarization of macrophages and promotes the protein level of MMP-9, thus aggravating AAA formation.     

啤酒大麦施用磷酸一铵的残效研究

本文通过田间小区3茬定位试验研究了啤酒大麦施用磷酸一铵的残留效果。结果指出，第1茬啤酒大麦施用的磷对第2茬棉花和第3茬啤酒大麦都有一定的残效，且前茬施磷量越大残效越明显。当第1茬啤酒大麦亩施磷量达到5．86kgP2O5时，第2茬棉花可以不施磷。     

施磷对不同收获时期青贮玉米碳水化合物积累的影响

为探讨磷肥对不同收获时期青贮玉米中碳水化合物积累的影响,试验以青贮玉米品种东青1号(Zea mays Dongqing No.1)为材料,设4个不同施磷水平,其P₂O₅施用量分别为P0(不施P₂O₅,CK)、P1(施P₂O₅ 50 kg/hm²)、P2(施P₂O₅ 100 kg/hm²)和P3(施P₂O₅ 150 kg/hm²)水平,分别于乳熟初期(8月21日)、乳熟中期(8月28日)、乳熟末期(9月4日)、蜡熟初期(9月10日)、蜡熟中期(9月15日)和蜡熟末期(9月20日)收割取样,测定磷肥(P₂O₅)对碳水化合物含量的影响。结果显示,在乳熟初期至蜡熟末期,各施磷水平间果糖和可溶性总糖含量均表现为P2＞P3＞P1＞P0,淀粉含量表现为P2＞P1＞P3＞P0,且各施磷水平间差异显著(P<0.05)。随着施磷量的增加,各水平蔗糖含量显著增加,P2和P3水平间差异不显著,但均显著高于其他水平(P<0.05);P0水平NDF和ADF含量最高,P2水平最低,且显著低于其他水平(P<0.05)。施磷(P₂O₅)可显著提高青贮玉米中果糖、蔗糖、可溶性总糖和淀粉含量(P<0.05),降低NDF和ADF含量(P<0.05),其中以施磷(P₂O₅)100 kg/hm²并于蜡熟初期收获时,东青1号青贮玉米的可溶性总糖含量最高,NDF和ADF含量最低,是较适宜的栽培利用方式。     

“磷酸盐”在肉制品中的作用

磷酸盐是目前世界各国应用最广泛的食品添加剂,对食品品质的改良起着重要的作用。一般将用于肉制品的磷酸盐：焦磷酸钠、三聚磷酸钠、六偏磷酸钠,以一定的比例配成复合磷酸盐使用。着重阐述了磷酸盐在肉制品中的作用机理、性状特征及使用方法,这些知识的掌握对提高肉制品的质量大有益处。     

磷酸氢二铵活化法制备活性炭的研究

以杉木屑为原料,采用磷酸氢二铵活化法制备活性炭。讨论了预处理温度、浸渍比和活化温度对活性炭碘吸附值的影响。结果表明,随着预处理温度、浸渍比和活化温度的升高,活性炭的碘吸附值均呈先升后降的趋势。在较佳生产工艺条件下:预处理温度160℃,浸渍比1.25:1,活化温度450℃,活性炭的碘吸附值达到930.2mg·g^-1。     

化学物质诱导香荚兰抗寒力的试验

试验表明：稀土、白糖、氯化钾和磷酸二氢钾均能显著或极显著地提高香荚兰的抗寒能力，使用浓度依次为４００、３３３．３、２５０和１０００倍效果最好。     

磷酸氢二铵复配硼酸锌处理麦秸秆纤维板的阻燃性能

麦秸秆作为我国高产农业副产品,目前的研究仅限于热压制板成型工艺方面,缺乏对其阻燃性能的探索。因此,现采用磷酸氢二铵(DAP)与硼酸锌(ZB)复配处理麦秸秆纤维,并热压成型,对其处理后的阻燃性能进行研究,得出阻燃剂最佳浓度及复配比例。试验结果表明:1)经过DAP和ZB复配阻燃剂处理的麦秸秆纤维制成的麦秸秆纤维板具有显著的阻燃效果;2)阻燃剂DAP与ZB比例为3:1,且阻燃剂总质量分数为10%~15%时的阻燃效果最为显著。     

不同施肥处理对杉木林土壤水源涵养功能的影响

[目的]林地土壤容重、孔隙度、蓄水性指标和土壤渗透性能反映土壤水源涵养功能大小,以连续施肥6 a的杉木林地为研究对象,研究不同处理的氮、磷肥对杉木林地土壤水源涵养功能的影响,为施肥杉木林地科学经营和水源涵养提供依据.[方法]对杉木林地进行不同的施肥处理:CK、N1(50 kg·hm-2a-1)、N2(100 kg·hm...     

施用不同浓度的磷酸二氢钾对香椿生长及养分的影响

为了提高木本蔬菜香椿的产量和质量,以湖南省湘乡市湘之椿农作物有限公司的矮化香椿为试验材料,施用不同浓度的磷酸二氢钾(KH_2PO_4)叶面肥,然后对香椿地径、老叶长度、小叶长度、小叶数量及叶片中的可溶性蛋白质、可溶性糖、氮(N)、磷(P)、钾(K)等指标进行了测定与分析。结果表明:施用不同浓度的KH_2PO_4对香椿生长及营养成分促进作用明显,浓度在0.5%~1.5%之间的叶面肥处理均能显著提高香椿的地径、老叶长度、小叶长度和数量,各指标随施肥浓度的增加均呈先升后降的趋势,但当其浓度超过2.0%时,KH_2PO_4对香椿老叶生长有抑制作用;不同浓度的KH_2PO_4对于老叶叶片中的可溶性糖、可溶性蛋白、N、P、K含量的提高均有显著效果。综合分析认为,浓度为1.0%的KH_2PO_4对香椿老叶叶片营养成分含量的提升效果最佳;KH_2PO_4处理下的香椿叶片中的N、P、K均呈现出显著正相关,且彼此之间存在一定增效作用。