供氮水平对金钗石斛生长、营养元素分布及品质的影响

Effects of Nitrogen Supply Levels on Growth,Nutrient Distribution and Quality of Dendrobium nobile

探究温室设施栽培下不同供氮水平对金钗石斛生长、营养元素分布规律及品质的影响,可为金钗石斛精准设施栽培和品质调控提供理论参考。以金钗石斛3年生植株为试验材料,通过测定形态指标、开花性状、不同时期和不同部位N、P、K元素含量变化和石斛碱含量,探究不同供氮水平(清水对照CK、1/2N、1N、2N)对其生长和品质的影响以及营养元素(N、P、K)在其体内转运分布规律。结果表明,不同供氮水平下植株生长趋势及N、P、K元素含量变化规律基本一致。植株地上部干物质量逐步增加,施氮处理效果显著优于对照,但不同供氮处理间差异并不显著。不同时期氮元素存在从老茎向新生茎转移的趋势。磷元素含量在不同部位呈先升高后降低的规律。1年生叶中钾元素含量较高(35.91 g/kg),2、3年生茎中钾元素含量显著低于其他部位。地上部分与地下部分氮元素比值在4—6月显著上升,而后逐渐下降,与营养生长期需氮特征一致。尽管磷元素比值呈显著下降趋势,但不同供氮水平对磷元素比值无显著影响。低供氮水平下的钾元素比值较高。在开花品质方面,1/2N和1N处理优于其他处理。施氮有助于植株体内石斛碱含量的增加,茎中石斛碱含量显著高于叶和根。非1年生茎中石斛碱的含量随着供氮水平的增加而减少,而1年生茎叶以及根中则表现相反。不同年生茎间石斛碱含量差异不显著。在植株不同部位中,以生长活跃的1年生叶、茎中N、P、K含量更高,老年茎含量较低,表明营养元素优先向幼嫩组织转移以满足生长的需求。营养生长期植株对N、P、K元素的需求量均较大,生殖期则逐渐下降,至次年开花期达到最低。营养生长向生殖生长过渡时期,适当增加磷肥的施用量,可促进假鳞茎的膨大和成熟。在生殖生长期,增施钾肥有利于营养物质的积累,施氮有助于石斛碱含量的增加,提高药用品质,而低氮处理有利于提高开花品质。

To explore the effects of different nitrogen supply levels on Dendrobium nobile growth,nutrient distribution and quality under greenhouse facility cultivation,so as to provide theoretical reference for its precise facility cultivation and quality control.Three-year-old plants of D.nobile were used as test materials.By measuring morphological indexes,flowering traits,and nitrogen(N),phosphorus(P)and potassium(K)content changes and dendrobine content in different periods and different parts of the plants,we investigated the effects on D.nobile growth and quality and the transfer and distribution of nutrient elements(N,P and K)in vivo under the different nitrogen supply levels(water control CK,1/2N,1N and 2N).The results showed that the growth trend of plants and the content changes of N,P and K under different nitrogen supply levels were basically the same.The dry matter weight of aboveground part increased gradually,and the effect of nitrogen application treatment was significantly better than that of the control,but the difference among different nitrogen supply treatments was not significant.There was a tendency of N to transfer from old stems to new stems in different periods.The P content in different parts of D.nobile increased first and then decreased.The K content of 1-year-old leaves was relatively high(35.91 g/kg),while that of 2-and 3-year-old stems was significantly lower than that of other parts.The ratio of nitrogen element in the aboveground part to that in the underground part increased significantly from April to June,and then gradually decreased,which was consistent with of nitrogen demand in the vegetative growth period.Although the phosphorus element ratio showed a significant downward trend,different nitrogen supply levels had no significant effect on the phosphorus element ratio.The potassium ratio was higher under low nitrogen supply levels.In terms of flowering quality,1/2N and 1N treatments were better than other treatments.Nitrogen application helped to increase the content of dendrobine in plants,and the content of dendrobine in stems was significantly higher than that in leaves and roots.The content of dendrobine in non-annual stems decreased with the increase of nitrogen supply level,but the opposite was observed in annual stems,leaves and roots.There was no significant difference in the content of dendrobine among stems of different years.Among different parts of the plant,the active annual leaves and stems had higher N,P and K contents,and the older stems had lower contents,indicating that nutrients were preferentially transferred to young tissues to meet the needs of growth.In the vegetative growth period,the demand for N,P and K was relatively high,and in the reproductive period,the demand gradually decreased,reaching the lowest in the flowering period of the next year.During the transition period from vegetative growth to reproductive growth,appropriately increasing the application amount of phosphorus fertilizer could promote the expansion and maturation of pseudobulbs.In the reproductive growth period,to increase the application of potassium fertilizer was beneficial to the accumulation of nutrients,and the application of nitrogen was helpful to increase the content of dendrobine and improve the medicinal quality,while the low nitrogen treatment was beneficial to improve the flowering quality.