Effects of Leaf Potassium Content on Growth Dynamics of Muskmelon and Developing a Coupling Model of Nitrogen and Potassium

Abstract

<jats:p>Nitrogen and potassium are two crucial nutrient elements that affect the yield and quality of crops. The aim of this study was to quantify the impacts of potassium on growth dynamics and quality of muskmelon, so as to optimize potassium management for muskmelon in a plastic greenhouse, and develop a coupling model of nitrogen and potassium. For this purpose, four experiments (two experiments with different levels of potassium treatment and planting dates, and the other two experiments with different ratios of nitrogen and potassium, and planting dates) on muskmelon (<jats:italic>Cucumis melo</jats:italic> L. ‘Nanhaimi’ and ‘Xizhoumi 25’) were conducted in a plastic greenhouse located at Sanya from Jan. 2014 to Sept. 2015. The quantitative relationship between leaf potassium content and growth dynamics and yield of muskmelon was determined and incorporated into a photosynthesis-driven crop growth model (SUCROS). Independent experimental data were used to validate the model. The critical leaf potassium content at the flowering stage for muskmelon ‘Nanhaimi’ and ‘Xizhoumi 25’ were 55.0 and 46.0 mg·g<jats:sup>−1</jats:sup>. The result showed that the coefficient of determination (<jats:italic>r</jats:italic><jats:sup>2</jats:sup>) between the predicted and measured values of leaf area index (LAI), direct weight of shoot (DWSH), direct weight of stem (DWST), dry weight of leaf (DWL), dry weight of fruit (DWF), fresh weight of fruit (FWF), soluble sugar content (SU), soluble protein content (PR), vitamin C (Vc), and soluble solids content (SO) of potassium model were 0.93, 0.98, 0.83, 0.96, 0.98, 0.99, 0.94, 0.94, 0.89, 0.85, and 0.90, respectively; and the relative root-mean-squared error (rRMSE) were 10.8%, 19.6%, 30.3%, 21.1%, 11.9%, 17.2%, 13.9%, 27.8%, 20.6%, and 10.1%, respectively. The two ways of nitrogen and potassium coupling (multiplicative coupling and minimum coupling) were compared, and the multiplicative coupling was used in model development finally. The <jats:italic>r</jats:italic><jats:sup>2</jats:sup> between the predicted and measured values of LAI, DWSH, DWST, DWL, DWF, FWF, SU, PR, Vc, and SO of nitrogen and potassium coupling model were 0.78, 0.91, 0.93, 0.94, 0.83, 0.89, 0.92, 0.95, 0.91, and 0.93, respectively; and their rRMSE were 9.2%, 12.4%, 11.8%, 43.2%, 6.6%, 7.2%, 6.85%, 4.98%, 6.61%, and 4.35%, respectively. The models could be used for the optimization of potassium, nitrogen, and potassium coupling management for muskmelon production in a plastic greenhouse.</jats:p>

Quality Improvement of Netted Melon (Cucumis melo L. var. reticulatus) through Precise Nitrogen and Potassium Management in a Hydroponic System

“…Accumulated studies have confirmed the success of hydroponic culture for several vegetable crops, such as tomato, lettuce, and netted melon, through improving water use efficiency and optimising both plant growth and yield quality by finer adjustments on macronutrients, including nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), or magnesium (Mg) [6][7][8][9][10][11]. N and K are the two most important macronutrients determining the plant growth, yield production, and quality [6,8,[12][13][14]. This has encouraged more research effort on establishing the precise N and K fertilisation schemes for crop plants to improve yield quality and efficiency of fertiliser use, and reduce the wastage of fertilisers and associated environmental pollution.…”

Fosthiazate inhibits root-knot disease and alters rhizosphere microbiome of Cucumis melo var. saccharinus

“…Globally, the area under melon cultivation was around 1,039,691 ha with a total production of 27,501,360 tons in 2019 (Faostat, 2019). In China, it is a key economic fruit crop which is cultivated over 376, 000 ha and produces more than 13 million metric tons fruit annually, with half of the melon production in the Hainan Province, China (Yang et al, 2019;Li et al, 2021).…”