育苗基质添加腐植酸促进番茄穴盘苗生长改善生理特性

摘要

[Objectives]In this study, we investigated the effect of humic acid addition on growth, nitrate reductase activity and photosynthetic parameters of tomato plug seedlings, which will provide a theoretical reference for the application of humic acid in plug seedling production.[Methods]The substrate used for tomato seedlings was composed of peat, vermiculite and perlite in volume ratio of 4 : 3 : 2, in which humic acid content was 54.5 g/L. Five treatments were designed according to the amount of humic acid added before seed sowing and recorded as CK (no addition), T1 (10 g/L), T2 (20 g/L), T3 (30 g/L) and T4 (40 g/L). Each treatment was repeated three times and each replication had three plug trays. When the fifth leaf appeared in tomato seedlings (about 29–31 days after cotyledons fully developed), the growth parameters, root activity, nitrate reductase activity, photosynthetic pigment contents, photosynthetic parameters and chlorophyll fluorescence parameters were measured.[Results]Treatment of T1, T2 and T3 significantly increased the plant heights and stem diameters, and the effects on the root dry weights were more significant than on the shoot dry weights. Compared with CK, T1 and T2 significantly increased the ratio of root to shoot and health seedling index, while T3 did not. T2 showed a distinct advantage in all the growth parameters, while T4 showed the worst performance. T1, T2 and T3 treatments significantly promoted the root activity and nitrate reductase activity, while T4 treatment decreased these two parameters. The contents of photosynthetic pigment were increased firstly and then decreased with the increase of humic acid content. All treatments except T4 significantly increased the Pn and Gs, and T2 had the highest values. All treatments increased the Ci compared to CK. The Tr was decreased with the increase of humic acid concentration, and the maximum value was in CK. The Fo and NPQ were decreased in T1 and T2, while increased in T3 and T4. The minimum and maximum values were observed in T2 and T4, respectively. The order of the Fv/Fm and ΦPSⅡ content in different treatments was T2 > T1 > CK > T3 >T4, in which T1 and T2 significantly increased these two parameters, while T3 and T4 significantly decreased these two parameters.[Conclusions]For the substrate of containing 54.5 g/L humic acid, the addition of some more humic acid will be able to enhance physiological activities, promote growth and cultivate vigorous tomato seedlings. The suitable amount of humic acid addition is 20 g/L of the substrate for plug seedlings of tomato.%【目的】以番茄为材料，研究穴盘育苗基质中腐植酸添加对幼苗生长及硝酸还原酶活性、光合参数等的影响，为培育优质壮苗和腐植酸的应用提供参考依据。【方法】番茄育苗基质以草炭、蛭石、珍珠岩按体积比4：3：2配成，其中腐植酸含量为54.5 g/L(约11.85%)，播种前在基质中分别添加折合纯腐植酸0(CK)、10 g/L (T1)、20 g/L (T2)、30 g/L (T3)、40 g/L (T4)，共5个处理，每处理3次重复，每个重复3个穴盘。待植株长到5叶1心(子叶展开后29～31天)时测定番茄幼苗的生长指标、根系活力、硝酸还原酶活性、光合色素含量、光合参数和叶绿素荧光参数。【结果】T1、T2、T3处理均显著提高了番茄幼苗的株高、茎粗，对番茄幼苗根干重的提高幅度大于地上部干重；T1、T2处理显著提高了根冠比和壮苗指数，T3处理与 CK差异不显著；各生长指标均以 T2处理表现最好，T4处理最差。T1、T2、T3处理显著提高了根系活力和硝酸还原酶活性，而 T4处理二者明显降低。基质中适当提高腐植酸含量，可提高番茄幼苗叶片各种光合色素含量，但腐植酸含量过高，则会降低各光合色素含量。T1、T2、T3处理的 Pn、Gs、Ci均显著高于 CK，均以 T2处理最高，T4处理的 Pn、Gs显著低于 CK，但其 Ci高于 CK；Tr表现为 CK最高，随腐植酸添加量的增加，逐渐降低。T1、T2处理的 Fo、NPQ均低于 CK，且以 T2处理的最低，T3、T4处理的均高于 CK，且以 T4处理的最高；各处理的Fv/Fm和ΦPSⅡ的大小顺序均为 T2> T1> CK > T3> T4，其中 T1、T2处理显著高于 CK，T3、T4处理则显著低于 CK。【结论】番茄育苗基质中腐植酸在已含有54.5 g/L的基础上以添加20 g/L能够更好地促进番茄穴盘苗生长，改善其生理活动，对培育壮苗有更好的效果。