长期施磷对水稻锌吸收、积累和转运的影响

Effects of long-term P application on absorption,accumulation and translocation of zinc in rice crop

水稻是中国南方地区的主要粮食作物,其籽粒锌营养强化是近年研究的热点,水稻磷与锌的吸收利用存在互作效应。研究长期不同施磷模式对水稻锌的吸收、积累与转运的影响,为通过合理施肥提高水稻的锌营养提供理论依据。依托22年的黄壤(水田)长期定位试验,选取其中7种施肥模式:不施肥(CK)、偏施氮肥(N)、偏施氮钾肥(NK)、平衡施用化肥(NPK)、单施有机肥(M)、1/2有机肥替代1/2NP(0.5MNP)、全量有机肥化肥配施(MNPK)。CK、N、NK处理不施磷,NPK、M、0.5MNP处理施磷量依次为P2O582.5、79.4、81.0 kg·hm^(-2),MNPK施磷量为P2O5161.9 kg·hm^(-2)。于水稻分蘖期、开花期及成熟期,采集土壤和植株样品,分析比较各处理土壤有效锌含量、植株锌含量及其锌积累和转运特征差异。水稻各生育时期土壤有效锌含量基本表现为MNPK≥M>0.5MNP>NPK≥CK>N,NK,长期施用有机肥可提高土壤有效锌含量;与NPK处理成熟期植株相比,CK、N、NK处理茎叶和籽粒锌含量分别提高了-2.0%~44.0%和15.7%~46.7%,MNPK处理茎叶和籽粒锌含量分别降低了22.0%~38.7%和12.0%~19.8%,M和0.5MNP处理籽粒锌含量提高了6.4%~14.4%;各处理成熟期茎叶和籽粒P/Zn分别为6.2~67.2和62.2~225.2,均以CK、N、NK处理最低,MNPK处理最高;不同施肥处理间水稻植株锌积累量无显著差异,锌转运量及其贡献率均以M处理最高,NPK和N处理最低,花后锌积累量及其对籽粒的贡献率则相反。相关分析和多因素方差分析结果表明,水稻茎叶和籽粒锌含量与磷含量和土壤有效磷含量呈显著负相关,土壤有效锌含量主要与有机肥施用量有关,而水稻茎叶和籽粒锌含量则主要受磷肥施用量影响。综上,长期不施磷可提高水稻籽粒锌含量,但严重制约水稻产量的提高,长期高量施磷可提高水稻籽粒产量,但却降低了籽粒锌含量。适宜施磷量下,有机无机配施既可实现作物高产又可提高籽粒锌含量,是黄壤稻田上实现作物高产优质的有效途径。此外,本研究中土施锌肥对提高水稻籽粒锌含量效果有限,为进一步提高水稻籽粒锌含量,还应重视叶面锌肥的施用。

Rice is the main cereal crops in southern China,nutrient biofortification of Zn in rice grain has attracted great attention in recent years.Zn absorption and utilization of rice are affected by the interaction between Zn and phosphorus(P).The aim of study was to provide a theoretical basis on Zn absorption,accumulation and translocation of rice by rational fertilization.The study was based on a successive 22-years field experiment in the yellow paddy soil.Seven treatments were chosen from the experiment,including CK,N,NK,NPK,M,0.5MNP and MNPK.CK,N,NK had no P2O5 input,NPK,M and 0.5MNP had P2O5 input of 82.5,79.4 and 81.0 kg·hm^(-2),respectively,and MNPK had P2O5 input of 161.9 kg·hm^(-2).Soil and rice aboveground parts were sampled at tillering,flowering and maturity stages,and the contents of Zn in soil and in straw and grain of rice were measured.Zn accumulation and transfer characteristics were calculated.The soil available Zn(DTPA-Zn)content at different growth stages of rice was basically ranked as follows:MNPK≥M>0.5MNP>NPK≥CK>N,NK,indicating that long-term application of organic fertilizer improved soil Zn availability.Compared with the plant maturity stage in NPK treatment,Zn content in stem leaf and grain increased by-2.0%~44.0%and 15.7%~46.7%respectively in CK,N and NK treatment.Zn content in stem leaf and grain decreased by 22.0%~38.7%and 12.0%~19.8%respectively in MNPK treatment,and Zn content in grain increased by 6.4%~14.4%in M and 0.5MNP treatments.The P/Zn ratios in straw and grain in the maturity stage were 6.2~67.2 and 62.2~225.2,respectively,which increased with the increase of P application rate.There was no significant difference in Zn accumulation among different fertilization treatments.The Zn translocation amount and its contribution rate to grain were the highest in M treatment,and the lowest in N and NPK treatment,while Zn accumulation amount in after-anthesis period and its contribution rate to grain were the opposite.Correlation analysis and multivariate analysis of variance showed that,Zn content in stem leaf and grain was negatively correlated with P content and soil available P,DTPA-Zn content was mainly affected by the amount of manure,and Zn content in rice grain was mainly affected by the amount of P fertilizer.In conclusion,long-term P deficiency could increase the Zn content of rice grain,but seriously restricted the improvement of rice yield.Long-term high P application could increase the yield of rice grain,but reduced the Zn content in rice grain.Under suitable P application rate,long-term integrated fertilization with organic manure and chemical fertilizers could not only realize crop high yielding,but also improve the Zn content and activity in grain,which is an effective way to achieve high yielding and high quality of rice crop in yellow paddy soil.In addition,the effect of application of Zn fertilizer to the soil on increasing Zn content of rice grain is limited,so more attention should be paid to apply Zn fertilizer by foliar spray in order to further improve the Zn content in rice grain.