Relative tillering rate(RTR)increased linear-ly with the increasing of leaf N concentration(NLV)has been already reported.To testwhether this relationship could be used toquantitatively explain the difference in tille...Relative tillering rate(RTR)increased linear-ly with the increasing of leaf N concentration(NLV)has been already reported.To testwhether this relationship could be used toquantitatively explain the difference in tilleringamong a wide range of N application,field ex- periments were conducted at the IRRI farm,Los Banos,Laguna,the Philippines.Two in- dica cultivars,IR 72 and IR68284H wereused.For each cultivar,12 treatments includ- ing 4 N levels(0,60,120,and 180kgN·ha)and 3 transplanting spacing(30×20,20×20,and 10×20cm)were arranged in a ran-domized split-plot design with 4 replications.The N treatments were designated as mainplots and spacings as subplots.Fourteen-day-old seedlings were transplanted with 3seedlings per hill.The subplot area was 20m~2.Nitrogen fertilizer was applied as basal,atmidtillering,and at panicle initiation in threeequal splits.P,K,and Zn were applied asbasal at normal dosage.The field was flooded.Plant samples were taken every 7-14 d from 14d after transplanting to flower展开更多
Leaf morphological and anatomical structure and carbon isotope ratio (δ^13C) change with increasing tree height. To determine how tree height affects leaf characteristics, we measured the leaf area, specific leaf m...Leaf morphological and anatomical structure and carbon isotope ratio (δ^13C) change with increasing tree height. To determine how tree height affects leaf characteristics, we measured the leaf area, specific leaf mass (ratio of leaf mass to leaf area [LMA]), thickness of the total leaf, cuticle, epidermis, palisade and sponge mesophyll, stomata traits and δ^13C at different heights of Parashorea chinensis with methods of light and scanning electron microscopy (SEM) and isotope-ratio mass spectrometry. The correlation and stepwise regression between tree height and leaf structure traits were carried out with SPSS software. The results showed that leaf structures and δ^13C differed significantly along the tree height gradient. The leaf area, thickness of sponge mesophyll and size of stomata decreased with increasing height, whereas the thickness of lamina, palisade mesophyll, epidermis, and cuticle, ratios of palisade to spongy thickness, density of stomata and vascular bundles, LMA and δ^13C increased with tree height. Tree height showed a significant relationship with all leaf indices and the most significant relationship was with epidermis thickness, leaf area, cuticle thickness, δ^13C. The δ^13C value showed a significantly positive relationship with LMA (R = 0.934). Our results supported the hypothesis that the leaf structures exhibited more xeromorphic characteristics with the increasing gradient of tree height.展开更多
文摘Relative tillering rate(RTR)increased linear-ly with the increasing of leaf N concentration(NLV)has been already reported.To testwhether this relationship could be used toquantitatively explain the difference in tilleringamong a wide range of N application,field ex- periments were conducted at the IRRI farm,Los Banos,Laguna,the Philippines.Two in- dica cultivars,IR 72 and IR68284H wereused.For each cultivar,12 treatments includ- ing 4 N levels(0,60,120,and 180kgN·ha)and 3 transplanting spacing(30×20,20×20,and 10×20cm)were arranged in a ran-domized split-plot design with 4 replications.The N treatments were designated as mainplots and spacings as subplots.Fourteen-day-old seedlings were transplanted with 3seedlings per hill.The subplot area was 20m~2.Nitrogen fertilizer was applied as basal,atmidtillering,and at panicle initiation in threeequal splits.P,K,and Zn were applied asbasal at normal dosage.The field was flooded.Plant samples were taken every 7-14 d from 14d after transplanting to flower
基金the National Natural Science Foundation of China (30070637)Beijing Municipal Science & Technology Commission Project "Drought re-sistant and water-saving species selection and application for Beijing urbangreenism" (D0605001040191)the Key Laboratory for Silvicuture andConservation, Ministry of Education Project "Water economic ecology re-search for Beijing urban greenbelt" (JD100220535).
文摘Leaf morphological and anatomical structure and carbon isotope ratio (δ^13C) change with increasing tree height. To determine how tree height affects leaf characteristics, we measured the leaf area, specific leaf mass (ratio of leaf mass to leaf area [LMA]), thickness of the total leaf, cuticle, epidermis, palisade and sponge mesophyll, stomata traits and δ^13C at different heights of Parashorea chinensis with methods of light and scanning electron microscopy (SEM) and isotope-ratio mass spectrometry. The correlation and stepwise regression between tree height and leaf structure traits were carried out with SPSS software. The results showed that leaf structures and δ^13C differed significantly along the tree height gradient. The leaf area, thickness of sponge mesophyll and size of stomata decreased with increasing height, whereas the thickness of lamina, palisade mesophyll, epidermis, and cuticle, ratios of palisade to spongy thickness, density of stomata and vascular bundles, LMA and δ^13C increased with tree height. Tree height showed a significant relationship with all leaf indices and the most significant relationship was with epidermis thickness, leaf area, cuticle thickness, δ^13C. The δ^13C value showed a significantly positive relationship with LMA (R = 0.934). Our results supported the hypothesis that the leaf structures exhibited more xeromorphic characteristics with the increasing gradient of tree height.