Low soil available phosphorus level reduces cotton fiber length via osmoregulation

Introduction Phosphorus (P) deficiency hinders cotton ( Gossypium hirustum L.) growth and development, seriously affecting lint yield fiber quality. However, it is still unclear how P fertilizer affects length. Methods Therefore, a two-year (2019-2020) pool-culture experiment was conducted using the split-plot design, with two cultivars (CCRI-79; low-P tolerant SCRC-28; sensitive) as main plot. Three soil available phosphorus (AP) contents (P 0 : 3 ± 0.5, 1 6 2 (control) 15 0.5 mg kg −1 ) were applied to plots, subplot, investigate impact of AP content on elongation Results Low decreased osmotically active solutes in fibers, including potassium ions (K + ), malate, soluble sugar, sucrose, by 2.2–10.2%, 14.4–47.3%, 8.7–24.5%, 10.1–23.4%, respectively, inhibiting vacuoles from facilitating through osmoregulation. Moreover, also reduced activities enzymes participated (plasma membrane H -ATPase (PM-H -ATPase), vacuole (V-H -translocating inorganic pyrophosphatase -PPase), phosphoenolpyruvate carboxylase (PEPC)). The PM-H -ATPase, V-H -PPase, PEPC 8.4–33.0%, 7.0–33.8%, 14.1–38.4%, 16.9–40.2%, transmembrane transport acidified conditions for cell wall, thus limiting elongation. Similarly, length 0.6–3.0 mm, mainly due 3.8–16.3% reduction maximum velocity (V Lmax ). Additionally, upper fruiting branch positions (FB 10–11 had higher V longer lengths under low AP. Discussion Cotton fibers malate -PPase yielded fibers. And sugar SCRC-28's more sensitive contrast those CCRI-79, possibly explaining SCRC-28 sensitivity