| Walnut(Juglans regia L)plant has a long history and is widely distributed in China.It is an important dried fruit oil tree species.Its fruit is rich in nutrients,has high economic and ecological benefits,and has great potential for industrial value mining.Over the years,it has developed rapidly.Today,China’s walnut cultivation area ranks first in the world,and its output accounts for about 50%of the world’s total output.To become an important economic tree species in my country,and an important part of my country’s agricultural industrialization.However,the cultivation technology of walnut in China is backward compared with other countries,and the walnut cultivation in some remote areas still lacks systematic management,resulting in reduced production and no production,which has adverse effects on industrial development and rural construction.Mineral nutrition is the basis for fruit tree growth and development,yield formation and quality improvement.Studying the dynamic changes of mineral nutrient elements in fruit trees is of great significance to clarify the demand dynamics,absorptive capacity and nutrient regulation of fruit trees for nutrient elements,and is also an important research direction in plant nutrition and fertilizer science.Numerous studies on the mineral nutrition of fruit tree leaves and fruits have been reported,but there are relatively few studies on the nutrient dynamic changes of dried fruit tree species.In particular,the systematic study on the dynamic changes of mineral nutrients in various parts of walnut has not been reported yet.Using the certified cultivar "Yucheng 1" in Chongqing and the local indigenous strains "Rice Walnut" and "Iron walnut" as materials,we studied the mineral nutrient content and cumulative dynamic changes of walnut leaves,fruits,xylem and phloem,in order to reveal the dynamic changes of walnut mineral nutrition.These characteristics provide a basis for the scientific management of walnut nutrients and promote the healthy and sustainable development of the local walnut industry.The results are as follows.(1)The growth of walnut leaves and fruits was affected by time with stage characteristics,and there were significant differences among varieties.The change trend of single leaf fresh weight was consistent with that of single leaf dry weight,which increased in stages from April to August and decreased at the end.Leaf water content fluctuated at a high level in the early and middle stages,and decreased in the late stage.The single leaf fresh weight and dry weight of "Yucheng No.1" were significantly higher than other strains in the whole cycle,and the water content was lower than other strains.The single fruit fresh weight increased fastest in the early stage and slowed down in the later stage.The dry weight of single fruit increased at a uniform rate from May to August,and stagnated or slightly decreased in September.Fruit moisture content decreased mainly from June to August,and decreased slowly in other time.M(30)has the smallest final fruit development.(2)The contents of 10 mineral nutrients of "Yucheng no.1" showed a certain regularity with the growth stage,and each element showed different or similar dynamic characteristics in leaf,fruit,phloem and xylem.The growth period of N,P,K and Zn leaves showed a general trend of decline,in which N decreased rapidly first and then slowly,P and Zn decreased rapidly first and then rose slightly,and then more remained in a certain level of fluctuation,while K decreased waviness.Leaf Ca,Mg,Cu firstly decreased from high to the lowest point in July(Ca,Mg)or August(Cu),then increased and reached the highest or sub-high point at the end of the period.Fe,Mn and B fluctuated at a relatively low level until reaching the lowest point in July,and then continued to rise sharply until reaching a high or sub-high point at the end of the period.The N,Fe,Mn and B in fruit were stable during the cycle.P,Ca,Zn and Cu decreased first and then increased;Mg and Fe showed a decreasing trend.The contents of N,Mn and Fe in phloem were stable.K increases first and then decreases;P,Ca,Mg,Zn and B decreased first and then increased.Fe and Mn in xylem are relatively stable.N Increasing trend;P and Zn decreased first and then increased;K,Ca,Cu,B increased first and then decreased;The Mg cycle fluctuates violently.During this period,there are two special periods: From April to June,and around July.During these two periods,the variation trend of various elements in multiple parts is consistent,and the contents of P,Mg and Zn in each part decrease rapidly from April to June.The content of Ca,Mg,Mn and B reached the trough in July,and the content of K reached the peak in July.For example,the content of K decreased after July,while the content of Ca,Mg,Mn and B increased after July.In this study,the nutrient contents of leaves,fruits,phloem and xylem in different periods can be used as reference indexes for nutritional diagnosis and nutrient management in local walnut production,especially leaves.The average value(and range)of mineral nutrients in walnut leaves during the whole growth period were N 25.42(18.21-32.67)g/kg,P 2.18(1.91-3.07)g/kg,K 9.12(5.75-14.32)g/kg,Ca22.55(8.25-34.43)g/kg,Mg 1.70(1.31-2.26)g/kg,Fe 117.60(80.88-183.46)mg/kg,Mn 94.91(67.04-138.90)mg/kg,Zn 16.17(12.52-27.86)mg/kg,Cu The contents of N,Mn and Cu in walnut leaves were 11.36(6.87 ～ 16.63)mg/kg and 20.96(12.66 ～ 27.83)mg/kg and B were 20.96(12.66 ～ 27.83)mg/kg.The contents of Ca were 4 times higher than those of other plants.The contents of P were low and medium elements were similar to those of K,Mg,Fe,Zn and B.The content of Ca and P is different from that of annual crops.The overall ranking of mineral element content(and proportion,with nitrogen as 100)is: Leaf N(100)>Ca(88.47)>K(38.69)>P(9.05)>Mg(7.00)>Fe(0.50)>Mn(0.34)>B(0.09)>Zn(0.07)>Cu(0.04),Fruit K(118.96)>N(100)>Ca(48.80)>P(13.44)>Mg(5.41)>Fe(0.18)>B(0.12)>Mn(0.11)>Zn(0.08)>Cu(0.07),Phloem Ca(436.53)>N(100)>K(65.51)>Mg(15.56)>P(14.37)>Fe(0.82)>Mn(0.45)>B(0.31)>Zn(0.19)>Cu(0.07),In xylem,Ca(117.40)>N(100)>K(75.58)>P(22.14)>Mg(15.85)>Fe(0.65)>B(0.26)>Zn(0.25)>Mn(0.19)>Cu(0.09).The proportion of each strain was consistent,but there were differences in different parts.In general,the ratio of leaf N,fruit K,xylem and phloem Ca was the largest.Cu ratio was the lowest in all parts.The ratio of N,Ca and K was larger in leaf early stage,but Ca exceeded N in leaf late stage.In the early stage,Fe is larger than Mn,and in the late stage,Mn overcomes.Phloem Ca always dominated,but fluctuated greatly,especially after February and August.The ratio of phloem B also increased significantly in February and after August.For most of the xylem,the proportion of K is similar to that of N..(3)The mineral element content of walnut was consistent and different among different varieties and tree ages.Among them,the variation trend of N,Ca,Fe,Zn and B in leaf,phloem showed little difference and strong consistency,and the variation trend of N,Cu and B in xylem also showed consistency.There are obvious differences in other element varieties and tree ages in other parts.such as: xylem P rose or fell in different strains after August,phloem K "Yucheng no.1" fluctuated more than other strains,xylem K fluctuated more in M(30)and T(30)than the other two strains,and xylem Fe showed significant difference between strains in June and August.In most cases,the content of N,P,Mn,Mg and B of "Yucheng 1" is higher than that of other strains,the content of T(30)Ca is higher than that of other strains,and the content of Fe is higher in M(30).At the beginning of growth period(April),the contents of N,Mn,Zn and B in leaves of M(80)were higher than those of other strains and trees,K was higher than that of M(30),and the contents of Ca,Mg and Fe in phloem were higher than that of M(30).There were no significant differences in phloem and xylem between the two tree ages,but the content of phloem and xylem was higher in the leaves of M(80),indicating that there were more reserve advantages transferred to primary leaves in older trees.(4)The same element has certain correlation between different parts.Fruit N,K,Ca,Fe and Zn were closely related to the same elements in other parts,among which,fruit N was significantly negatively correlated with leaf N,fruit K,Ca and Zn were significantly positively correlated with the same elements in leaf,fruit N was significantly positively correlated with xylem N,and fruit K,Ca and Fe were significantly or significantly correlated with the same elements in phloem.The correlation between different elements was different in different parts,with strong correlation between different elements in leaves,followed by fruit,and less correlation between elements in xylem and phloem.The main correlations in leaves were as follows: N had a significant or extremely significant relationship with elements except Mg,among which,N was positively correlated with P,K,Zn and Cu,and negatively correlated with Ca,Fe,Mn and B;P is positively correlated with N,Zn,Cu,and negatively correlated with Ca,Fe,Mn,B.K was positively correlated with N,and negatively correlated with Ca,Mg,Fe,Mn and B.Ca was negatively correlated with N,P and K,and positively correlated with Mg,Fe,Mn and B.Fe and B are strongly related to elements except Zn and Cu.Mn has a strong relationship with all elements.(5)The accumulation of elements in single fruit of "Yucheng no.1" before harvesting was N(0.44g)>Ca(0.33g)>K(0.07g)>P(0.06g)>Mg(0.02g)> Fe(0.61 mg)>B(0.37 mg)>Mn(0.37mg)>Zn(0.32 mg)>Cu(0.26 mg)).The accumulation of mineral elements in fruits generally showed an upward trend,which was similar to the change The accumulation of biomass accumulation,but showed a more obvious stage characteristics.The trend of accumulation of N,P,Mg,Z,Cu and B was uniform during the growth cycle,and the accumulation of N,Mg and B slowed down in the last stage,while the accumulation of Ca was slow in the early stage and accelerated after July.The rapid accumulation of Fe occurred from June to July,and the rapid accumulation of K and Mn occurred from June to July and July to August,respectively,and finally a A large amount of outward migration occurred.The accumulation of elements in single leaf before deciduous leaves was Ca(0.23g)>N(0.17g)>K(0.05g)>P(0.02g)>Mg(0.02g)>Fe(1.36mg)>Mn(1.27 mg)>B(0.20mg)>Zn(0.14mg)>Cu(0.07mg)).In general,N,P and K increased first and then decreased,reaching81.81%,73.66% and 77.30% of the pre-deciduous values in April,respectively,and reaching the highest value in July,followed by outward shift of leaves.Ca accumulation decreased sharply in July and then increased rapidly again.Mg,Fe,Mn showed an increasing trend,which slowed down significantly from June to July.B in the beginning and August to September accumulation faster;The accumulation of Zn and Cu mainly depends on the initial stage,which accumulated 85.14% and95.48% respectively in April,and basically stagnated in the later stage.All strains and tree age elements had the same accumulation trend.The accumulation of all elements in leaves of "Yucheng no.1" was significantly higher than that of other strains.Fruit in August was significantly higher than other varieties except K element.The accumulation of K,Zn and Cu in M(80)fruits was significantly higher than that in other strains in June,but only K was still the highest in August. |
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