鲁棉532不同种植密度对盐碱地棉饲两熟种植效益及土壤理化性状的影响

以一熟春棉(鲁棉研37号)为对照,研究棉饲两熟模式下3种不同种植密度(7.5万株·hm^(-2)、9.0万株·hm^(-2)、10.5万株·hm^(-2))对早熟棉鲁棉532棉田周年产量和效益,及其生长发育、光合特性和土壤理化性状的影响,以期明确黄河三角洲盐碱地棉饲两熟模式下鲁棉532的适宜种植密度。结果表明,与一熟春棉相比,鲁棉532棉饲两熟模式虽然棉花产量降低9.1%,但周年总投入降低了8.0%,周年纯收益显著提高了67.5%;株高、单株果枝数、单株结铃数显著减少,但是单位面积总铃数与春棉相当;净光合速率、叶面积指数显著降低,透光率显著增加;土壤有机质和养分含量提高,土壤含盐量和pH降低,但与春棉差异不显著。棉饲两熟模式下,适当增大鲁棉532种植密度能显著提高群体光合生产能力,增加群体总铃数,从而提高籽棉产量和周年效益。当棉花密度为9.0万株·hm^(-2)时,周年收益、籽棉产量、总铃数和光合速率显著提高,分别比7.5万株·hm^(-2)、10.5万株·hm^(-2)提高5.4%、4.5%,5.0%、4.1%,40.6%、6.6%和8.4%、18.7%。不同种植密度对土壤理化性状无显著影响。因此,在黄河三角洲盐碱地中低产棉田按棉饲两熟种植鲁棉532,宜选择9.0万株·hm^(-2)的种植密度。

Atmospheric Corrosion Monitoring of Field-exposed Q235B and T91 Steels in Zhoushan Offshore Environment Using Electrochemical Probes

This work aimed to in-situ monitor the atmospheric corrosion of steels exposed to Zhoushan offshore environment by using electrochemical noise（EN） technique. A portable EN monitoring system was established and two electrochemical probes（named as Q235 B and T91） were designed. Experimental results indicated that the noise resistance of T91 steel was higher than that of Q235 B steel, revealing that the corrosion resistance of T91 was higher than that of Q235 B. A 60-day monitoring result indicated that the noise resistance was well correlated with the weight loss data. Wavelet analyses results of EN data indicated that Q235 B underwent uniform corrosion and T91 suffered from localized corrosion, which was further confirmed by the surface observation. It is concluded that EN can be used as a new method to identify the corrosion form and corrosion resistance in atmospheric conditions.