Abstract:

This study aims to clarify the relationship between source-sink coordination and yield in six peanut varieties, including ‘Shunhua 11’ (SH11), ‘Shunhua 14’ (SH14), and their parents ‘Luhua 14’ (LH14), ‘Huayu 19’ (HY19), ‘Kainong 176’ (KN176), and high-yield variety ‘Fenghua 1’ (FH1). Physiological, biochemical, or enzyme-linked immunosorbent assays were used to measure several photosynthetic parameters, the activities of sucrose phosphate synthase (SPS) and sucrose synthase (SS), as well as sugar, protein, and fat content in the leaves or pods of each variety. Phenotypic assessments were performed to obtain yield-related data such as pod weight, kernel weight, and quantity per plant. It was found that ‘SH14’ exhibited a net photosynthetic rate (Pn) of (24.40±1.06) μmol/(m²·s), higher than those in other varieties during the flowering and pod-setting period. At the maturation stage, ‘SH14’ maintained higher relative chlorophyll content (SPAD values of 32.80±2.00 and 40.60±0.62 for the third and fourth leaves from the top, respectively). Additionally, during the pod-filling stage, ‘SH14’ showed higher SPS and SS-I (degradation direction) activity and lower SS-II (synthesis direction) activity in the kernels. Compared to other varieties, ‘SH14’ and ‘KN176’ demonstrated outstanding performance in multiple sink size-related indicators. Their pod weight per plant, total number of pods, and total number of kernels were (51.82±3.69) and (52.86±16.33) g, 43.67±4.36 and 52.11±16.56, and 68.67±4.85 and 71.11±15.96, respectively. Although ‘SH14’ had lower plant biomass than that of ‘LH14’, ‘FH1’, and ‘KN176’, its harvest index (HI) and root-to-shoot ratio (R/S) were higher than those of other varieties (HI and R/S of ‘SH14’ were 0.61±0.04 and 0.096±0.026, respectively; the second-highest HI was ‘KN176’ at 0.60±0.05, and the second-highest R/S was ‘SH11’ at 0.080±0.022). These results indicate that ‘SH14’ exhibits better source-sink coordination than other varieties, including its maternal parent ‘HY19’ and paternal parent ‘KN176’. The well-developed sink organs of ‘SH14’ provide a crucial structural foundation for high yield, in the meanwhile, its harmonious sink-source relationship and unobstructed “flow” ensure the effective distribution and accumulation of assimilates in pods and kernels.

Key words: peanut (Arachis hypogaea), photosynthetic capacity, source-sink relationship, surcrose synthase-related enzymes, distribution of photoassimilates, yield, harvest index (HI), root-shoot ratio (R/S)