Lentil's transparent and thin seed coat is controlled by a recessive gene (_tan_) which moderates the tannin precursors that are responsible for seed darkening during cooking and the preservation period [9]. It is worth noting that both findings of our research group [10; 11; 12; 13] and those of other research teams (for a review see [PERSON] et al. [1]) indicate that the genetic diversity present within and among lenti populations is rich enough to provide material for genetic studies and manipulation of this trait. Phenolic acids, stilbenes and flavonoids such as flavanones, flavones, dihydroflavonols, flavonols, flavan-3-ols, anthocyanin and proanthocyanidins, also known as condensed tannins, are some of the derivatives of polyphenic compounds that play an important role in the properties of the seed coat [14]. The biosynthesis of tannins begins with the conversion of L-phenylalanine to trans-cinnamic acid, which is catalyzed by phenylalanine ammonia-lyase (PAL). Chalcone synthase (CHS) is the key enzyme that catalyzes the first step in the branch that leads to the flavonoid pathway [15]. Chalcone isomerase (CHI) then speeds up the chemical reaction that converts the yellow-colored chalcone into the colorless naringenin. Following this isomerization, flavanone 3-hydroxylase (F3H) transforms naringenin into dihydrokaempferol (DHK) which is hydroxylated by flavonoid 3'-hydroxylase (F3H) to form dihydromyticetin (DHM) [16]. Transcription factors, such as basic helix-loop helix (bHLH), that interfere with the pathway determine the regulation of several biosynthetic enzymes such us, F3H, F3H, flavonoid-3'-5'-hydroxylase (F3'5H), flavonoid synthase (FLS), dihydroflavonol 4-reductase (DFR), anthocyanin synthase (ANS), anthocyanin reductase (ANR) and leucoanthocyanidin reductase (LAR) that are considered to affect the pigmentation in the lentil seed coat. These enzymes are reported as key enzymes for the biosynthesis of flavan-3-ols, which are attributed as the monomers of polymerized proanthocyanidins [15; 16; 17; 18]. While the impact of tannin content on seed coat hardness is recognized, there is a limited understanding of the factors influencing their accumulation. Feedback from local farmers underscores the substantial influence of environmental variables. Their observations reveal that for certain lentil varieties, within the same variety and field, the percentage of hard seeds that are resistant to boiling can vary from year to year in a seemingly random manner. This prompts a worthwhile investigation into the role of diverse field factors that may influence tannin accumulation during lentil seed development. One such factor, susceptible to fluctuations due to environmental conditions, is the availability of phosphorus (P) in the soil. P stands as a vital macronutrient crucial for the growth and development of plants. It plays a pivotal role in essential metabolic processes, including the synthesis of adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide phosphate hydrogen (NADPH), it is involved in the formation of nucleic acids and phospholipids [19]. It is also well known that soil P dynamics are affected by the frequency and intensity of soil drying and rewatering [20]. P deficiency is reported to induce the increase in certain phenolic substances in all the vegetative parts of the lentil plants [21]. However, our knowledge of how P levels, above or below optimal doses, affect transcriptional regulation and gene expression during seed development is limited. In recent years, next-generation sequencing technologies have facilitated the study of lentil's genome (-4.3 Gbp), and the most recent effort in developing lentil genome assemblies for both the cultivated lentil (_Lens culinaris_) and its wild relative (_Lens erroides_) was effectuated by [PERSON] et al. [22].