| Humic acid(HA)is a promising natural resource to be utilized as an alternative for increasing crop production.It is a naturally occurring polymeric organic compound and is produced by the decay of organic materials and is found in soil,peat and lignites.Humic acid serves as a catalyst in promoting the activity of microorganisms in soil.HA had beneficial effects on nutrient uptake by plants,and was particularly important for the transport and availability of micronutrients.Humic acids have been complexes with sodium(Na),potassium(K),magnesium(Mg),zinc(Zn),calcium(Ca),iron(Fe),copper(Cu),and with various other elements to overcome a particular element deficiency in soil.This study was carried out to obtain the best way and best concentration of humic acid in soilless culture and using this result to study the influence of humic acid under NPK deficiency on physiological,biochemical parameters,vegetative growth,fruit parameters,yield and fruit quality.In addition to,investigate role of humic acid in improving substrates properties.1.Effect of soil and foliar application of humic acid on yield and quality of cucumber(Cucumis Sativus L.)under soilless culture(Trail.1).In this study,seven treatments were as follows: T1: recommended dose of NPK fertilizer(RDF)+ 0 % humic acid,control;T2: RDF+ 1% humic acid(soil application);T3: RDF+ 2.5 % humic acid(soil application);T4: RDF+ 4% humic acid(soil application);T5: RDF+ 1% humic acid(foliar spray);T6: RDF + 2.5% humic acid(foliar spray)and T7: RDF+ 4% humic acid(foliar spray).As per treatment,soil application of humic acid was applied to substrate and foliar spray of humic acid was applied to the leaves.HA was added to the plants after 30 days from transplanting at three times during the growing season at 15-day intervals.All fertilizer doses were given to the plants at the first day of transplanting and continued during the whole growing season.The main results were summarized as follows:a)Cucumber plants were affected by different concentrations and submission ways of humic acid.The optimum concentration with optimum way was 1% humic acid applied-soil.This treatment resulted in the highest plant height,number of leaves,leaf area,and stem diameter compared with the control and others treatments.b)The treatment by 1% HA soil application had a highly significant increase on total chlorophyll content,the increase in total chlorophyll content was 19.97% compared with control.c)Treating cucumber plants by 1% HA soil application showed a highly significant effect on cucumber fruit quality parameters.The increase in protein content was 27.51% compared with control.While,the increase in vitamin C content in fruit was 25.89% compared with control.d)Using of 1% HA soil application significantly increased root activity in compared with control,the increase in root activity was 51.76% compared with control.2.Influence of humic acid application on cucumber(Cucumis Sativus L.)growth,fruit quality and N assimilation under NPK deficiency(Trail.2).The best treatment obtained from experiment one(1% HA soil application)was used to investigate role of humic acid under NPK deficiency on cucumber growth.The treatments were as follows: T1:(100% NPK + 0 % humic acid)control;T2:(85% NPK + 0 %humic acid);T3:(70% NPK + 0 % humic acid);T4:(85% NPK+ 1% humic acid);T5:(70% NPK+ 1% humic acid).After 30 days from transplanting,HA was added to the substrate three times during the growing season at 15-day intervals.The main results were as follows:a)The treatment by 85% NPK+ 1% HA recorded a highly significant effect in total yield.The increase in total yield was 6.65% compared with control and 15.68% compared with 85% NPK+ 0% HA.b)Supplying cucumber plants by 85 % NPK + 1% HA had significantly increased chlorophyll content,photosynthetic rate,and root activity.The increase was 9.46 %,19%,and 16.48 % respectively compared with 85 % NPK + 0 % HA.c)Fruit quality contents showed a highly significant result by 85 % NPK + 1% HA compared with 85% NPK + 0 % HA.The increase in vitamin C content,titrable acid and protein content was 17.91%,26.31% and 14% respectively by 85 % NPK + 1% HA compared with 85% + 0 % HA.d)The NR,Ni R,GOGAT and GS enzymes activities showed a highly significant increase by 85 % NPK + 1% HA compared with 85% NPK + 0 % HA.The NR,Ni R,GOGAT and GS increased to be 32.75 %,36.56 %,63.52 % and 31.77 % respectively compared with 85% NPK + 0 % HA.3.The change of buffering capacity of different substrates by applying humic acid(Trail.3).The best concentration from experiment one(1% HA soil application)was used to study the role of humic acid on characteristics change of different culture media.The treatments were as follows: T1:(sand + 0 % humic acid);T2:(sand + 1 % humic acid);T3:(cocopeat + 0 % humic acid);T4:(cocopeat + 1% humic acid);T5:(sand: cocopeat 1:1+ 0% humic acid)and T6:(sand: cocopeat 1:1+ 1% humic acid),HA mixed with the various substrates before transplanting.The main results were as follows:a)The treatment by cocopeat + 1% humic acid had significantly increased cucumber morphological parameters compared with all other treatments.b)Humic acid had a positive effect on different substrates properties,and increased p H buffering capacity(p HBC)and cation exchange capacity.The increase in alkali buffering capacity was 60 %,19.04 % and 54.54% while the increase in acidic buffering capacity was 67.56 %,48.31 % and 47.61 % by T2,T4 and T6 compared with T1,T3 and T5 respectively.On the other hand,the increase in cation exchange capacity(CEC)was 71.42 %,36.82 % and 24.87 % by T2,T4 and T6 compared with T1,T3 and T5 respectively.c)Supplying different substrates by humic acid caused a highly significant increase in total organic carbon(TOC),organic matter(OM)and total nitrogen(TN)for all of the different substrates tested relative to the substrates without HA.The increase in TOC was 76.47 %,11.92 % and 48.80 %.Meanwhile,the increase in OM was 76.51 %,12.15 % and 48.81 %.In addition to the increase in TN was 58.92 %,24.53 % and 34.92 % by T2,T4 and T6 as compared with T1,T3 and T5. |
PDF Full Text Request