Twice-split phosphorus application alleviates low-temperature impacts on wheat by improved spikelet development and setting

Extreme low-temperature incidents have become more frequent and severe as climate change intensifies. In Huang-Huai-Hai wheat growing area of China, the late spring coldness occurring at the jointing-booting stage (the anther interval stage) has resulted in significant yield losses of winter wheat. This study attempts to develop an economical, feasible, and efficient cultivation technique for improving the low-temperature (LT) resistance of wheat by exploring the effects of twice-split phosphorus application (TSPA) on wheat antioxidant characteristics and carbon and nitrogen metabolism physiology under LT treatment at the anther interval stage using Yannong 19 as the experimental material. The treatments consisted of traditional phosphorus application and TSPA, followed by a -4 degrees C LT treatment and natural temperature (NT) control at the anther interval stage. Our analyses showed that, compared with the traditional application, the TSPA increased the net photosynthetic rate (Pn), stomatal conductance (Gs), and transpiration rate (Tr) of leaves and reduced the intercellular carbon dioxide concentration (Ci). The activity of carbon and nitrogen metabolism enzymes in the young wheat spikes was also increased by the TSPA, which promoted the accumulation of soluble sugar (SS), sucrose (SUC), soluble protein (SP), and proline (Pro) in young wheat spike and reduced the toxicity of malondialdehyde (MDA). Due to the improved organic nutrition for reproductive development, the young wheat spikes exhibited enhanced LT resistance, which reduced the sterile spikelet number (SSN) per spike by 11.8% and increased the spikelet setting rate (SSR) and final yield by 6.0 and 8.4%, respectively, compared to the traditional application. The positive effects of split phosphorus application became more pronounced when the LT treatment was prolonged.