Balancing the Nutrient Needs: Optimizing Growth in Malus sieversii
Seedlings through Tailored Nitrogen and Phosphorus Effects
Abstract
The impact of nitrogen (N) and phosphorus (P) on the physiological and
biochemical processes crucial for tree seedling growth is substantial.
Although the study of plant hydraulic traits in response to N and P is
growing, comprehensive research on their combined effects remains
limited. Malus sieversii, a key ancestral species of modern
apples and a dominant species in Xinjiang’s Tianshan wild fruit forest,
is witnessing a decline due to climate change, pests and diseases,
compounded by challenges in seedling regeneration. Addressing this, a
four-year study was conducted to determine the optimal fertilization
method for it. The experiment explored varying levels of N (N10, N20,
N40) and P (P2, P4, P8), and their combined effects (N20Px: N20P2,
N20P4, N20P8; NxP4: N10P4, N20P4, N40P4), assessing their impact on gas
exchange, hydraulic traits, and the interplay among functional traits in
Tianshan Mountains’ M. sieversii seedlings. Our study revealed
that all nitrogen treatments enhanced gas exchange, while phosphorus
addition negatively impacted it. N10 significantly increasing leaf
hydraulic conductivity. All phosphorus-inclusive fertilizers adversely
affected hydraulic conductivity. P8, N20P4 and N20P8 notably increased
seedlings’ vulnerability to embolism. Seedlings can adaptively adjust
multiple functional traits in response to nutrient changes. The research
suggests N10 and N20 as the most effective fertilization treatments for
M. sieversii seedlings in this region, while fertilization
involving phosphorus is less suitable. This study contributes valuable
insights into the specific nutrient needs of it, vital for conservation
and cultivation efforts in the Tianshan region.