Response of growth, metabolism and yield of Dendrocalamopsis oldhami to long-day photoperiod and fertilizer compensation

The effects of long-day photoperiod on growth, photosynthetic fluorescence, carbon and nitrogen metabolism, and yield of Dendrocalamopsis oldhami and the compensation effects of fertilization were investigated. A completely randomized design was used with two light factors (bamboo culms cultivated in solar greenhouse under long-day [Ls] and short-day [Ln] treatments); two organic nitrogen fertilizer levels (application of organic fertilizer [OF] and no organic fertilizer [NF]); and three nitrogen fertilizer levels (Low [N-0], medium [N-1] and high nitrogen [N-2]). Leaf chlorophyll and fluorescence parameters (phi P-o, PIABS, and ETo/CSm) decreased and DIo/CSm increased in Ls compared to Ln. Indole acetic acid (IAA) and gibberellic acid (GA(3)) levels decreased, whereas abscisic acid (ABA) increased. Leaf area decreased and leaf dry mass increased. The contents of carbon and nitrogen metabolism-related enzymes (nitrate reductase, glutamine synthetase, amylase, and sucrose synthase) and products (total nitrogen, organic carbon, soluble sugar, and starch) increased. Single bamboo shoot weight and diameter at breast height decreased, whereas shoot quantity and total yield increased. Fertilizer application significantly affected physiological growth and yield in the two light treatments, thus promoting carbon and nitrogen metabolism. The phi P-o, PIABS, IAA, and GA(3) contents increased slightly, whereas ABA levels decreased. Shoot quantity, individual weight, and total yield improved. IAA, soluble sugar, and total yield to organic manure and light were lower than those of nitrogen levels (F-N > F-L, F-O). Other indicators showed lower responses to different fertilization treatments than the light factor (F-L > F-N, F-O). The ability of D. oldhami to alter its morphological and physio-biochemical traits and yield in response to variations in light applications may translate into high phenotypic plasticity. Fertilization significantly improved photoplasticity of D. oldhami. Under Ls, D. oldhami had high metabolic rates, was easily inhibited by light, and showed accelerated leaf senescence, and shoot quantity and total output increased. However, the quality of individual shoots decreased. Different fertilization treatments affected D. oldhami differently under the two light intensities. Ls sensitivity to nitrogen was higher. Fertilization could delay leaf dormancy and senescence under Ls treatment. Organic fertilizer addition could improve yield more effectively, with OFN1 being the optimal fertilization level.