## 1 Introduction  
Tomatoes (_solanum Lycopersicum_ L.) are rich in nutrients and have a unique flavor, making them popular among consumers as vegetables and fruits [1, 2, 3]. Tomatoes are one of the most widely cultivated vegetables in the world. China has the highest total tomato production in the world, with annual production of more than 67 million tons, sufficient to meet the population's daily needs [4]. In recent years, as individuals' economic status has improved, dietary preferences have shifted towards quality rather than quantity. Consumers now prefer flavorful tomatoes and are willing to pay higher prices [5, 6]. Therefore, cultivating high-flavor-quality tomatoes is crucial in meeting the market demand and improving the economic benefits of tomato production.  
The aroma produced by food is composed of a variety of volatile aromatic compounds and is detected when the volatiles enter the nasal cavity and are perceived by the olfactory system [7, 8]. The aroma is an important component of the tomato flavor quality and, along with sugars and acids, plays a key role in the acceptability of tomato fruits by consumers [9, 10, 11]. However, over the past few decades, tomato cultivation has focused on high yields, disease resistance, and an extended shelf life, resulting in a notable reduction in the characteristic aroma of the fruits and the flavor quality. Thus, fruit volatile compounds have become a key research focus in terms of enhancing tomato flavor. In recent years,the effects of the genotype [11; 12; 13] and production management [14; 15; 16; 17] on the volatile compounds of tomato fruit have been studied, and nutrient management has been shown to play a significant role in determining the composition of volatile compounds [18; 19; 20].  
Organic nutrient solutions are abundant in essential mineral nutrients such as nitrogen (N), phosphorus (P), and potassium (K), as well as soluble organic compounds such as small-molecule organic acids, free amino acids, sugars, beneficial microorganisms, and their byproducts. This combination provides organic nutrient solutions with excellent nutritional value and biocontrol properties [21]. Organic nutrient solutions, with their fluid characteristics, can be applied using spraying equipment or directly through microirrigation systems such as drip irrigation. Compared to traditional solid organic fertilizers, organic liquid fertilizers can more easily achieve labor-saving, precise, and efficient management based on crop growth and development [22]. Thus, organic nutrient solutions are considered novel fertilizer sources that meet the requirements of modern fertigation and have considerable application prospects [23; 24]. Many studies have been conducted on the effects of the formulation, irrigation concentration, and irrigation scheduling (irrigation volume and frequency) of organic nutrient solutions on crop growth, yields, and fruit flavor quality [20; 22; 25]. The synthesis and metabolism of substances in fruits vary at different developmental stages; therefore, the influence of organic nutrient solutions on the flavor substances in fruits may be related to the fruit development stage. However, studies on the effects of organic nutrient solutions on tomato fruit volatiles based on the fruit developmental stage are scarce.  
This study aimed to explore an approach to improving tomato fruit volatiles through organic instead of inorganic nutrient solutions using precision fertilization. Therefore, the effects of irrigation with a fully inorganic nutrient solution (control; NNNN) and an organic rather than inorganic nutrient solution (OIINS) on the type and content of tomato fruit volatiles during the flowering-fruit setting (ONNN), fruit expanding (NONN), color turning (NNON), and harvest (NNNO) stages of the first spike were investigated.