Xiao Zhang

Premature harvesting is a prevalent concern in rice cultivation, significantly impacting both grain yield and quality. However, there is limited information regarding the specific effects of premature harvesting on rice quality, particularly in terms of taste value. Consequently, this research aimed to assess the distribution of rice maturity and its implications for rice quality. A comprehensive study was conducted, comprising a one-year survey study and two years of field experiments, to examine the effects of premature harvesting on head rice rate, taste value, amylose content, and protein content. In the survey study, the results indicated that, on average, more than one-quarter of the samples exhibited a green rice rate exceeding 10% at harvest, with the majority having rates surpassing 15%. Premature harvesting was found to significantly reduce grain weight, head rice rate, and taste value, especially when the green rice rate exceeded 15%. Similarly, research experimentation demonstrated that premature harvesting significantly decreased the head rice rate and taste value, accompanied by a reduction in amylose content and an increase in protein content. The head rice rate (r = −0.148 **, p < 0.01), taste value (r = −0.217 **, p < 0.01), amylose content (r = −0.854 **, p < 0.01), and protein content (r = 0.475 **, p < 0.01) exhibited significant correlations with the green rice rate. These findings indicated that optimizing the harvest date is crucial to achieving a low green rice rate (<15%), thereby ensuring high head rice rate, taste value, and amylose content, along with low protein content.

Rice (Oryza sativa L.), as one of the most significant food crops worldwide, holds paramount importance for global food security. Throughout its extensive evolutionary journey, rice has evolved a diverse array of defense mechanisms to fend off pest and disease infestations. Notably, labdane-related diterpenoid phytoalexins play a crucial role in aiding rice in its response to both biotic and abiotic stresses. This article provides a comprehensive review of the research advancements pertaining to the chemical structures, biological activities, and biosynthetic pathways, as well as the molecular regulatory mechanisms, underlying labdane-related diterpenoid phytoalexins discovered in rice. This insight into the molecular regulation of labdane-related diterpenoid phytoalexin biosynthesis offers valuable perspectives for future research aimed at improving crop resilience and productivity.

Plants have evolved a sophisticated defense system that employs various hormone pathways to defend against attacks by insect pests. Cytokinin (CK) plays an important role in plant growth and stress tolerance, but the role of CKs in plant–insect interaction remains largely unclear. Here, we report that CKs act as a positive regulator in rice resistance against brown planthopper (BPH), a devastating insect pest of rice. We found that BPH feeding promotes CK biosynthesis and signaling in rice. Exogenous application of CKs significantly increased the rice resistance to BPH. Increasing endogenous CKs by knocking out cytokinin oxidase/dehydrogenase (OsCKXs) led to enhanced resistance to BPH. Moreover, the levels of the plant hormone jasmonic acid (JA) and the expression of JA-responsive genes were elevated by CK treatment and in OsCKXs knockout plants. Furthermore, JA-deficient mutant og1 was more susceptible to BPH, and CK-induced BPH resistance was suppressed in og1. These results indicate that CK-mediated BPH resistance is JA-dependent. Our findings provide the direct evidence for the novel role of CK in promoting insect resistance, and demonstrate that CK-induced insect resistance is JA-dependent. These results provide important guidance for effective pest management strategies in the future.