| Eco-chemometrics is a science that studies the composition of chemical elements in biological organisms and the energy balance of ecosystems.Its research scales can be detailed to the molecular level,and can also be extended to the regional and global levels to achieve different scales of chemometrics covering molecules,cell organs,individuals,communities,ecosystems,regions and globally.In this paper,non-noded Italian bolting lettuce was used as experimental material.Firstly,soil culture experiment was carried out under the medium fertility level,and the growth stages of lettuce were divided by the growth rate of leaves.Secondly,soil culture experiments were carried out under medium and high fertility levels.Meanwhile,the quantitative changes of carbon,nitrogen,phosphorus and their ecological chemistry in lettuce leaves at different growth stages were studied.Finally,nitrogen and phosphorus nutrients are added and reduced in proportion to the nutrient solution through a water culture experiment to construct liquid nitrogen and phosphorus nutrient ratios with different nutrients.Ecological chemistry measurement characteristics ofcarbon,nitrogen and phosphorus in lettuce leaves,photosynthetic characteristics,growth indexes?fresh/dry weight of overground parts?,physiological indexes?soluble sugar content,soluble protein content,nitrate and nitrite content?were studied,and hydroponics nutrient solution was optimized by taking lettuce leaf element stoichiometric indexes with better fertility level as the standard.The results of this study can integrate the local schemes of lettuce nutrient regulation in different growth stages,and optimize the overall scheme of dynamic regulation and supply of N and P nutrients in a timely,appropriate and suitable proportion,thus providing a new regulatory approach for precision fertilization of protected vegetables.The main conclusions of this study are as follows:?1?The lettuce is determined as the early stage of rapid growth before 11.1 leaves,the lettuce is determined as the rapid growth period between 11.1 and 24.8 leaves,and the lettuce is determined as the late stage of slow growth after 24.8 leaves by drawing the cumulative growth diagram of leaf age.?2?When the leaf age of non-bolting Italian cabbage is less than 11.1,the contents of C,N and P in leaves fluctuate slightly around 453mg·g-1,44mg·g-11 and 2.4mg·g-1 respectively,while the contents of C:N,C:P and N:P fluctuate slightly around 10.2,188 and 18.3 respectively.When the leaf age of the lettuce is between 11.1 and 24.8,the contents of C,N and P in the leaves fluctuate slightly around 465mg·g-1,47mg·g-1 and 3.0mg·g-1 respectively,while the contents of C:N,C:P and N:P fluctuate slightly around 9.9,157 and 15.9 respectively.When the leaf age of the lettuce is more than 24.8,the contents of C,N and P in the leaves fluctuate slightly around 470mg·g-1,50mg·g-1 and 2.6mg·g-1 respectively,while the contents of C:N,C:P and N:P fluctuate slightly around 9.4,178 and 19.1 respectively.?3?Based on the eco-stoichiometric characteristics,photosynthetic index,quality and yield of lettuce,the nutrient control of lettuce was carried out as follows:The optimum concentrations of N and P in lettuce at the pre-slow growth period were36.23-72.46 mg·L-11 and 5.82-11.64 mg·L-1,respectively.The optimum concentrations of N and P were 36.23-72.46 mg·L-1 and 8.83-14.55 mg·L-1,respectively.The optimum concentrations of N and P in nutrient solution at the post-slow growth period were 36.23-72.46 mg·L-1 and11.64-17.46 mg·L-1 respectively. |
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