■磷(P)缺乏阻碍棉花(GossypiumhirustumL.)的生长和发育,严重影响皮棉产量和纤维质量。然而,目前尚不清楚磷肥如何影响纤维长度。
■因此,使用分裂地块设计进行了为期两年(2019-2020)的泳池培养实验,以两个棉花品种(CCRI-79;耐低磷和SCRC-28;低磷敏感)为主要地块。在地块上施用了三种土壤有效磷(AP)含量(P0:3±0.5,P1:6±0.5和P2(对照),15±0.5mgkg-1),作为子图,研究土壤AP含量对棉纤维伸长率和长度的影响。
■低土壤AP(P0和P1)降低了棉纤维中渗透活性溶质的含量,包括钾离子(K+),苹果酸,可溶性糖,和蔗糖,2.2-10.2%,14.4-47.3%,8.7-24.5%,和10.1-23.4%,分别,通过渗透调节抑制液泡促进纤维伸长。此外,土壤AP缺乏也降低了参与纤维伸长的酶的活性(质膜H+-ATPase(PM-H+-ATPase),液泡膜H+-ATP酶(V-H+-ATP酶),液泡膜H+转运无机焦磷酸酶(V-H+-PPase),和磷酸烯醇丙酮酸羧化酶(PEPC))。PM-H+-ATP酶,V-H+-ATP酶,V-H+-PPase,PEPC减少了8.4-33.0%,7.0-33.8%,14.1-38.4%,和16.9-40.2%,分别,抑制渗透活性溶质的跨膜运输和纤维细胞壁的酸化条件,从而限制了纤维的伸长。同样,土壤AP缺乏使纤维长度减少0.6-3.0毫米,主要是由于纤维伸长的最大速度(VLmax)减少了3.8-16.3%。此外,在低土壤AP下,上果枝位置(FB10-11)具有较高的VLmax和较长的纤维长度。
■具有较高苹果酸含量和V-H-ATPase和V-H-PPase活性的棉纤维产生较长的纤维。与CCRI-79相比,SCRC-28纤维中的苹果酸和可溶性糖含量以及V-H-ATPase和PEPC活性对土壤AP缺乏更敏感,这可能解释了SCRC-28纤维长度对低土壤AP的敏感性。
UNASSIGNED: Phosphorus (P) deficiency hinders cotton (Gossypium hirustum L.) growth and development, seriously affecting lint yield and fiber quality. However, it is still unclear how P fertilizer affects fiber length.
UNASSIGNED: Therefore, a two-year (2019-2020) pool-culture experiment was conducted using the split-plot design, with two cotton cultivars (CCRI-79; low-P tolerant and SCRC-28; low-P sensitive) as the main plot. Three soil available phosphorus (AP) contents (P0: 3 ± 0.5, P1: 6 ± 0.5, and P2 (control) with 15 ± 0.5 mg kg-1) were applied to the plots, as the subplot, to investigate the impact of soil AP content on cotton fiber elongation and length.
UNASSIGNED: Low soil AP (P0 and P1) decreased the contents of the osmotically active solutes in the cotton fibers, including potassium ions (K+), malate, soluble sugar, and sucrose, by 2.2-10.2%, 14.4-47.3%, 8.7-24.5%, and 10.1-23.4%, respectively, inhibiting the vacuoles from facilitating fiber elongation through osmoregulation. Moreover, soil AP deficiency also reduced the activities of enzymes participated in fiber elongation (plasma membrane H+-ATPase (PM-H+-ATPase), vacuole membrane H+-ATPase (V-H+-ATPase), vacuole membrane H+-translocating inorganic pyrophosphatase (V-H+-PPase), and phosphoenolpyruvate carboxylase (PEPC)). The PM-H+-ATPase, V-H+-ATPase, V-H+-PPase, and PEPC were reduced by 8.4-33.0%, 7.0-33.8%, 14.1-38.4%, and 16.9-40.2%, respectively, inhibiting the transmembrane transport of the osmotically active solutes and acidified conditions for fiber cell wall, thus limiting the fiber elongation. Similarly, soil AP deficiency reduced the fiber length by 0.6-3.0 mm, mainly due to the 3.8-16.3% reduction of the maximum velocity of fiber elongation (VLmax). Additionally, the upper fruiting branch positions (FB10-11) had higher VLmax and longer fiber lengths under low soil AP.
UNASSIGNED: Cotton fibers with higher malate content and V-H+-ATPase and V-H+-PPase activities yielded longer fibers. And the malate and soluble sugar contents and V-H+-ATPase and PEPC activities in the SCRC-28\'s fiber were more sensitive to soil AP deficiency in contrast to those of CCRI-79, possibly explaining the SCRC-28 fiber length sensitivity to low soil AP.