Abstract:
Objective To study the response of leaf traits to soil P addition and the change of leaf P fractions distribution pattern with the addition of P in 10-year-old Cunninghamia lanceolata (Lamb.) Hook. plantation in subtropical region, so as to provide a scientific basis for improving the productivity of Chinese fir plantation
Method Three plots were selected, with six treatments in each plot. The P addition amounts of each treatment lasting for three years were 0 (CK), 60 (P1), 120 (P2), 180 (P3), 240 (P4), 300 (P5) kg·hm−2·a−1, respectively, . Leaf traits including specific leaf area (SLA), leaf dry matter content (LDMC), leaf nitrogen (N), leaf phosphorus (P), N/P, maximum net photosynthetic rate (Amax), photosynthetic nitrogen and phosphorus use efficiency (PNUE, PPUE), and phosphorus fractions including nucleic acids, phospholipids, metabolic, residual, and inorganic phosphorus (Pi) were studied to explore their responses to P addition.
Result Compared with CK, SLA increased by 37.9% and 25.7%, and LDMC decreased by 9.4% and 12.5% under P2 and P3 treatments. There were no significant differences in leaf N content among different soil P gradients, but leaf P content increased by 29.4% to 49.4% compared with CK, and N/P decreased by 18.2% to 27.3% relative to CK. PNUE, PPUE, and Amax reached their maximum values under P3 treatment, increasing by 174.9%, 116.4%, and 125.9% relative to CK, respectively. Except for P2 and P3 treatments, leaf phosphorus fractions tended to increase in nucleic acids proportion. The positive correlation between metabolic phosphorus and PNUE also indicated that it was an important factor in increasing the net photosynthetic rate of leaves.
Conclusion Amax is the highest under treatment P3, which significantly increases PNUE and PPUE, alleviates P limitation, and promotes growth of Chinese fir.
下载: