The coupling effect of nutrient solution EC （electrical conductivity） levels and CR （circulation rate） on the morphology and quality, in hydroponically grown lettuce was assessed. Lettuce was grown at 5 treatments...The coupling effect of nutrient solution EC （electrical conductivity） levels and CR （circulation rate） on the morphology and quality, in hydroponically grown lettuce was assessed. Lettuce was grown at 5 treatments fi＇om High EC ＆ Low CR to Low EC ＆ High CR. The environmental parameters were controlled in a 20 m^2 plant factory during the hydroponic cultivation with the following values： irradiated by blue and red light-emitting diode lighting with PPFD （photosynthetic photon flux density） value of 150 mol·m^-2·s^-1 for 16 hours per day; Temperature was maintained at 22.0 ℃ during the photoperiod and 16.0 ℃ in dark cycle. The results demonstrate that growing lettuce can be adopted using nutrient solution with lower EC levels and higher CR. The results also indicate that the effect of bi-directional coupled EC and CR resulted in expansion of root length but reducing the root biomass. Nitrate content was significantly reduced.展开更多
Temperature, as an important feature of hydroponic nutrient solution, is closely related to dissolved oxygen content of nutrient solution and growth status of plant roots. How to precisely adjust the temperature of nu...Temperature, as an important feature of hydroponic nutrient solution, is closely related to dissolved oxygen content of nutrient solution and growth status of plant roots. How to precisely adjust the temperature of nutrient solution is the key to obtain high quality and high yield of hydroponic vegetables over summer. With Lactuca sativa vat. crispa ＇Luosheng No.3＇ as the test material, the effect of chiller cooling technology on the temperature of nutrient solution, as well as on the yield and quality of Luosheng No.3, in over-summer hydroponic cultivation was studied. The results showed that the chiller cooling technology controlled the nutrient solution temperature in a reasonable range （（20 ± 1）℃） and promoted the growth and dry matter accumulation of Luosheng No.3, instead of affecting the quality. In short, the chiller cooling technology is applicable to the temperature regulation of nutrient solu- tion in hydroponics over summer.展开更多
Unstable pH of nutrient solution in hydroponic systems is a major obstacle to production.To simplify the management of nutrient solution pH and attenuate negative effects of pH on plant growth,this study investigated ...Unstable pH of nutrient solution in hydroponic systems is a major obstacle to production.To simplify the management of nutrient solution pH and attenuate negative effects of pH on plant growth,this study investigated the effect of different buffer salt additions on nutrient solution pH,ion uptake,growth and photosynthesis of Yamazaki lettuce,with the equivalent concentrations of macro-element unchanged.The results indicated that the pH of nutrient solution was buffered to varying degrees by the 2 mol/L HCO_(3)^(-),1 mol/L HCO_(3)^(-),and 0.33 mol/L HPO_(4)^(2-)The 0.33 mol/L HPO_(4)^(2-)treatment fluctuated most with a pH of 1.74 units,while the addition of HCO_(3)^(-)buffered nutrient solution pH was better,with higher pH values(7.2-7.7).The CK-pH control solution,1 mol/L HCO_(3)^(-)and 0.33 mol/L HPO_(4)^(2-)treatments all promoted the uptake of ion and then the growth of lettuce was better in comparison with the CK-pH no adjustment treatment,while the 2 mol/L HCO_(3)^(-)treatment inhibited K uptake and reduced the availability of Fe,the shoot and root fresh weight of lettuce decreased by 21.3%and 10.1%,respectively.In addition,although the chlorophyll content and net photosynthetic rate under 1 mol/L HCO_(3)^(-)and 0.33 mol/L HPO_(4)^(2-)treatments were significantly lower than the CK-pH control solution treatment,there were no significant differences in leaf length and leaf number of lettuce among them,and shoot fresh weight per plant was 83.09,82.95,and 78.92 g,respectively.In conclusion,adding 1 mol/L HCO_(3)^(-)to the nutrient solution in a single dosage not only buffered the pH of nutrient solution better but also promoted ion uptake,it had no negative effects on the growth,photosynthesis and ion uptake of hydroponic lettuce in comparison with the CK-pH control solution treatment.Therefore,1 mol/L HCO_(3)^(-)can be used as a buffer during the growth of hydroponic lettuce and reduce frequent addition of acids or alkalis,and then simplify the management of nutrient solution for hydroponic lettuce production.展开更多
文摘The coupling effect of nutrient solution EC （electrical conductivity） levels and CR （circulation rate） on the morphology and quality, in hydroponically grown lettuce was assessed. Lettuce was grown at 5 treatments fi＇om High EC ＆ Low CR to Low EC ＆ High CR. The environmental parameters were controlled in a 20 m^2 plant factory during the hydroponic cultivation with the following values： irradiated by blue and red light-emitting diode lighting with PPFD （photosynthetic photon flux density） value of 150 mol·m^-2·s^-1 for 16 hours per day; Temperature was maintained at 22.0 ℃ during the photoperiod and 16.0 ℃ in dark cycle. The results demonstrate that growing lettuce can be adopted using nutrient solution with lower EC levels and higher CR. The results also indicate that the effect of bi-directional coupled EC and CR resulted in expansion of root length but reducing the root biomass. Nitrate content was significantly reduced.
基金Supported by Science and Technology Innovative Leading Fund of Ningxia Academy of Agriculture and Forestry Sciences(NKYZ-16-1101)~~
文摘Temperature, as an important feature of hydroponic nutrient solution, is closely related to dissolved oxygen content of nutrient solution and growth status of plant roots. How to precisely adjust the temperature of nutrient solution is the key to obtain high quality and high yield of hydroponic vegetables over summer. With Lactuca sativa vat. crispa ＇Luosheng No.3＇ as the test material, the effect of chiller cooling technology on the temperature of nutrient solution, as well as on the yield and quality of Luosheng No.3, in over-summer hydroponic cultivation was studied. The results showed that the chiller cooling technology controlled the nutrient solution temperature in a reasonable range （（20 ± 1）℃） and promoted the growth and dry matter accumulation of Luosheng No.3, instead of affecting the quality. In short, the chiller cooling technology is applicable to the temperature regulation of nutrient solu- tion in hydroponics over summer.
基金funded by the Beijing Capital Agriculture Group Self-Supporting Science and Technology Projects[Grant No.SNSPKJ 2022(01)]Chinese Universities Scientific Fund(Grant No.2023TC087).
文摘Unstable pH of nutrient solution in hydroponic systems is a major obstacle to production.To simplify the management of nutrient solution pH and attenuate negative effects of pH on plant growth,this study investigated the effect of different buffer salt additions on nutrient solution pH,ion uptake,growth and photosynthesis of Yamazaki lettuce,with the equivalent concentrations of macro-element unchanged.The results indicated that the pH of nutrient solution was buffered to varying degrees by the 2 mol/L HCO_(3)^(-),1 mol/L HCO_(3)^(-),and 0.33 mol/L HPO_(4)^(2-)The 0.33 mol/L HPO_(4)^(2-)treatment fluctuated most with a pH of 1.74 units,while the addition of HCO_(3)^(-)buffered nutrient solution pH was better,with higher pH values(7.2-7.7).The CK-pH control solution,1 mol/L HCO_(3)^(-)and 0.33 mol/L HPO_(4)^(2-)treatments all promoted the uptake of ion and then the growth of lettuce was better in comparison with the CK-pH no adjustment treatment,while the 2 mol/L HCO_(3)^(-)treatment inhibited K uptake and reduced the availability of Fe,the shoot and root fresh weight of lettuce decreased by 21.3%and 10.1%,respectively.In addition,although the chlorophyll content and net photosynthetic rate under 1 mol/L HCO_(3)^(-)and 0.33 mol/L HPO_(4)^(2-)treatments were significantly lower than the CK-pH control solution treatment,there were no significant differences in leaf length and leaf number of lettuce among them,and shoot fresh weight per plant was 83.09,82.95,and 78.92 g,respectively.In conclusion,adding 1 mol/L HCO_(3)^(-)to the nutrient solution in a single dosage not only buffered the pH of nutrient solution better but also promoted ion uptake,it had no negative effects on the growth,photosynthesis and ion uptake of hydroponic lettuce in comparison with the CK-pH control solution treatment.Therefore,1 mol/L HCO_(3)^(-)can be used as a buffer during the growth of hydroponic lettuce and reduce frequent addition of acids or alkalis,and then simplify the management of nutrient solution for hydroponic lettuce production.
