土壤耕作方式对双季稻镉积累分配特性的影响

Effect of Soil Tillage Method on Cd Accumulation and Distribution Characters of Double-Cropping Rice

为探讨镉污染稻田双季稻最优土壤耕作方式,于2015年~2017年,以陵两优211与威优46为材料,在湖南湘潭中度镉污染稻田开展定位试验,比较研究了双季免耕(G1)、双季翻耕(G2)、双季旋耕(G3)、早旋晚免(G4)、早翻晚免(G5)等5种土壤耕作方式下双季稻镉积累分配特性.结果表明:(1)晚稻根镉含量以成熟期最高,但早稻规律不明显.土壤耕作方式明显影响根镉含量,免耕处理最高,翻耕处理最低,(2)翻耕可降低早稻成熟期茎镉含量,但晚稻成熟期茎镉含量的处理间差异存在年际间差异,(3)早、晚稻叶镉含量随生育进程推进表现持续增长趋势,不同土壤耕作方式间叶镉含量差异显著,多年免耕可降低叶镉含量,而多年旋耕可提高叶镉含量,(4)水稻齐穗至成熟期穗镉含量一般呈持续增长趋势,其增幅以翻耕处理最大,免耕处理最小,(5)3年早稻地上部镉累积量均以G5处理最高,而晚稻地上部镉累积量2015年以G5处理最高,2016和2017年以G2处理最高,3年均以G1、G4、G5处理较低.可见,土壤耕作方式对双季稻镉积累分配有明显影响,翻耕促进水稻地上部镉积累,而免耕可降低水稻穗部镉含量和地上部镉累积量.

To explore the optimal soil tillage method for double-cropping rice in Cd contaminated paddy field,the positioning test was conducted in medium Cd contaminated paddy field of Xiangtan,Hunan in 2015-2017 with Lingliangyou 211 and Weiyou 46 as materials to comparatively study the Cd accumulation and distribution characters of double-cropping rice under the 5 soil tillage methods of notillage in two seasons(G1),plowing in two seasons(G2),rotaiy tillage in two seasons(G3),rotary tillage in early rice and no-tillage in late rice(G4)and plowing in early rice and no-tillage in late rice(G5).The results showed that:(1)The Cd content in roots of late rice reached the peak value at maturity,while early rice had no clear trend.Cd content in roots was clearly affected by soil tillage method,and that in no-tillage treatment was the highest,and that in plowing treatment was the lowest.(2)Plowing could reduce the Cd content in stems of early rice at maturity,while there were interannual differences in the Cd content in stems of late rice at maturity.(3)The Cd content in leaves of early and late rice showed a trend of continuous growth with the advancement of the fertility process,and Cd content in leaves exited significant difference among the different treatments of soil tillage methods,and that was decreased by years of no-tillage and increased by years of rotary tillage.(4)Cd content in panicles showed the sustained growth trend from full-heading to maturity,and the increasing range in plowing treatment was the biggest,and the in creasing range in no-tillage treatment was the smallest.(5)The Cd accumulation in upland of early rice in G5 treatment in 3 years was highest,while that of late rice in G5 treatment in 2015 and in G2 treatment in 2016 and 2017 were respectively highest,which were lower than that in G1,G4 and G5 treatment.These results showed that Cd accumulation and distribution of double-cropping rice was clearly affected by soil tillage methods.Plowing promoted Cd accumulation in upland part of rice,while no-tillage reduced Cd content in panicles and Cd accumulation in upland part of rice.