论文部分内容阅读
Abstract Calcium nitrate and EGTA （calcium inhibitor） were sprayed on Dafeng Apricot during young fruit period. The results showed that calcium （Ca） spraying during young fruit period increased Ca and VC contents in the fruit， improved SOD and POD activities， and declined K content， K/Ca and the occurrence of fruit cracking. When spraying calcium inhibitor during young fruit period， it aggravated fruit cracking.
Key words Apricot； Exogenous calcium； Calcium inhibitor； Fruit cracking
Apricot is one of main fruit trees in North China， and belongs to deciduous tree of Rosaceae. Apricot blooms early， and fruit ripening is also early. It occupies important position in fruit market and is deeply loved by people. Hebei is main production region of apricot， and both area and yield are in the second place in China. In recent years， fruit cracking of apricot affects appearance quality， and brings larger pressure on production and sale of apricot fruit， causing that fruit farmers enthusiasm obviously declines. There have been the researches on fruit cracking of jujube[1-2]， cherry， tomato[3]， pomegranate[4]， pear[5-6]， apricot[7]， apple[6]， peach[8]. But there are fewer researches on the impacts of Ca and calcium inhibitor on fruit cracking of apricot. In this paper， Ca and calcium inhibitor treatments of Dafeng Apricot during young fruit period were conducted. Fruiting cracking situation of apricot was investigated regularly， and soluble sugar， titratable acid， VC， some mineral elements and SOD activity in fruit were measured during mature period， which aimed to provide theoretical basis for producing high-quality apricot fruit.
Materials and Methods
Test materials
Test material was selected from Apricot Demonstration Garden， Shijiazhuang Fruit Research Institute， Hebei Academy of Agriculture and Forestry Sciences. The test apricot variety was 15-year Dafeng Apricot， with plant and line spacing of 4 m×6 m and good growth. Experimental Ca was calcium nitrate （AR）， calcium inhibitor was EGTA （AR）， and they were both prepared into 0.3% of solution by distilled water.
Ca and calcium inhibitor were sprayed in 10 days after flowering period， once per 7 days， which continuously sprayed for three times. Control was spraying clean water， single plant in a district， which repeated for three times.
Methods
Observation of fruit cracking and sample collection： started from June 1， fruit cracking situation was investigated per 7-10 days. If there was fruit cracking， it was recorded and marked. During fruit ripening period， fruits in different treatments were collected and conserved in ultra low temperature freezer， which was used for the determination and analysis of related indexes. Measurement of soluble sugar content： anthrone colorimetry； VC content determination： 2， 6-DCPIP method； measurement of mineral element content： nitric acid-hydrogen peroxide for digestion， atomic absorption spectrometry； SOD activity determination： NBT photoreduction.
Results and Analysis
The impacts of Ca and calcium inhibitor on fruit cracking of apricot
Started from June 1， fruit cracking situation of apricot was investigated （Table 1）. On June 10， fruit cracking started to appear in control and calcium inhibitor treatment， and fruit cracking rate was lower. On June 17， fruit cracking rate quickly increased， while fruit cracking started to appear in Ca treatment， which was 3%. To June 29， fruit cracking rate of calcium inhibitor treatment reached 58%. Above results showed that Ca treatment significantly declined fruit cracking rate， while calcium inhibitor treatment aggravated fruit cracking. It illustrated that Ca content played an important role in fruit cracking of apricot. Liu Huichao et al. thought that calcium inhibitor spraying caused fruit deformation and dehiscence of apple[9]. The research of Nie Guowei et al. showed that fruit cracking of apricot was negatively related to Ca content[7]. The research result was consistent with prior results.
The impacts of Ca and calcium inhibitor on soluble sugar， titratable acid and VC contents in apricot fruit
Seen from Table 2， both soluble sugar and titratable acid in apricot fruit had insignificant difference among different treatments， and ratio of sugar to acid also had insignificant difference. VC content in apricot of Ca treatment increased by 9.2% than control， while VC content in calcium inhibitor treatment declined by 16.75% than control， and they both had significant difference from control. The research of Dong Caixia et al. showed that the mixed solution of 20 mg/L NAA+0.5% CaCl2 spraying flowers， leaves and young fruits of tomato during flowering and young fruit periods could significantly increase Ca and VC contents in fruit[10]. The research results showed that Ca treatment improved VC content in fruit， while calcium inhibitor treatment declined VC content， and VC content was negatively related to fruit cracking of apricot.
The impacts of Ca and calcium inhibitor on mineral nutrient elements in apricot fruit
Seen from Table 3， Ca treatment improved Ca content， while calcium inhibitor treatment declined Ca content， and the difference was significant. Ca treatment declined K content in the fruit， with significant difference from control， while K content in calcium inhibitor treatment had insignificant difference from control. Fe， Cu and Mn contents among different treatments had insignificant difference. In this paper， Ca treatment improved Ca content and declined K content and K/Ca， illustrating that high Ca and lower K was negatively related to fruit cracking. Seen from Table 4， Ca spraying during young fruit period improved SOD and POD activities in fruit， with significant difference， while the difference between calcium inhibitor treatment and control was insignificant. Yang Chunxiang et al. reported that CaCl2 solution spraying in suitable concentration in germination， budding and late flowering stages of nectarine could make SOD activity maintain higher level[8]. The test results showed that Ca treatment improved SOD and POD activities in fruit， which was consistent with prior result.
Conclusions and Discussion
Ca spraying in young fruit period increased Ca and VC contents， SOD and POD activities in apricot fruit， declined K content， K/Ca and fruit cracking. Calcium inhibitor spraying in young fruit period had contrary result to that of Ca treatment， which aggravated fruit cracking of apricot.
Fruit cracking is a kind of physiological disorder in fruit development process， and the lack or accumulation of mineral nutrition is bound to affect the physiological disorder[9]. Many researches show that Ca spraying could decrease fruit crack[11-14]. Ca could combine with pectin substance in cell wall， forming calcium pectate. It increases the elasticity of protoplasm， and enhances pressure resistance and extensibility of cell， anti cracking ability of fruit. Therefore， Ca spraying could ease fruit cracking of apricot. The research results showed that Ca spraying in young fruit period of Dafeng Apricot increased Ca content in fruit， thereby enhancing cells extensibility in fruit and declining fruit cracking of apricot， which was consistent with prior results. Ca inhibitor declined Ca content in fruit， which aggravated fruit cracking.
SOD and POD are important protective enzymes in organism[15-16]. The test results showed that Ca treatment improved Ca content， SOD and POD activities of fruit， thereby easing fruit cracking of apricot， and calcium inhibitor treatment had contrary result.
References
[1] LI KZ.Initial study on fruit cracking mechanism of jujube[J]. Acta Horticulturae Sinica， 1984（2）： 61-62.
[2] WANG XL.Preliminary observation on fruit development anatomy of jujube[J].Chinese Bulletin of Botany， 1974（2）： 161-169.
[3] BANGERTH F. Investigations upon Ca related physiological disorders[J]. Phytopathologische Zeitschrift， 1973， 77： 1， 20-37.
[4] JIANG GL. Cause and prevention of pomegranate fruit crack[J].Xiandai Horticulture ， 2016（2）： 112. [5] CHEN QL，YANG XP，ZHANG JG，et al.The impacts of different treatments on fruit crack and quality of pear[J].South China Fruits ）， 2016， 45（6）： 110-112.
[6] CHEN XH.Influence of bagging on disease and pest of apple and pear fruit[J].Hebei Fruits， 2000（1）： 5， 7.
[7] NIE GW，LI K，TIAN YQ，et al.Correlation of fruit cracking and mineral nutrient content in apricot[J].Journal of Agriculture，2017，7（5）：23-27.
[8] YANG CX，LI XL，GAO DS.Effect of Ca2+ on membrane lipid peroxidation and activity of protective enzymes in nectarine flowers and young fruit under chilling stress[J].Deciduous Fruits，2004， 36（6）：1-3.
[9] LIU HC，HAN ZH.Influence of two calcium inhibitors on development and cell ultrastrcture of young apple fruit[J].Journal of Fruit Science，2002， 19（4）：211-214.
[10] DONG CX，ZHOU JM，FAN XH，et al.Effects of different ways of Ca supplements on the Ca content and forms in mature fruits of tomato[J].Plant Nutrition and Fertilizer Science， 2004， 10（1）： 91-95.
[11] WANG DJ，ZHANG LH.Initial study on rule and control technology of fruit cracking of navel orange[J].South China Fruits，1992，21（2）：17-19.
[12] BAI CH，TIAN SP.Study on Ca of fruit tree[J].Journal of Fruit Science， 1989， 6（2）：121-124.
[13] PENG J.The effect of Ca（NO3）2 and GA sprayed on leaves on the fruit cracking of ‘Nuomici’ Litchi[J].Acta Horticulturae Sinica， 2001（4）： 348-350.
[14] JIANG JK.Study on fruit cracking of Cuiguan Pear[J].South China Fruits， 2003， 32（3）： 62-63.
[15] WANG AG.Oxygen metabolism in plants//YU SW， TANG ZC.Plant physiology and molecular biology[M].Beijing： Science Press，1998.
[16] GUAN JF，SHU HR，ZHANG LC. Regulatory effects of calcium and its antagonists on cell membrane permeability of apple flesh[J].Journal of Fruit Science，2004， 21（5）：402-405.
Key words Apricot； Exogenous calcium； Calcium inhibitor； Fruit cracking
Apricot is one of main fruit trees in North China， and belongs to deciduous tree of Rosaceae. Apricot blooms early， and fruit ripening is also early. It occupies important position in fruit market and is deeply loved by people. Hebei is main production region of apricot， and both area and yield are in the second place in China. In recent years， fruit cracking of apricot affects appearance quality， and brings larger pressure on production and sale of apricot fruit， causing that fruit farmers enthusiasm obviously declines. There have been the researches on fruit cracking of jujube[1-2]， cherry， tomato[3]， pomegranate[4]， pear[5-6]， apricot[7]， apple[6]， peach[8]. But there are fewer researches on the impacts of Ca and calcium inhibitor on fruit cracking of apricot. In this paper， Ca and calcium inhibitor treatments of Dafeng Apricot during young fruit period were conducted. Fruiting cracking situation of apricot was investigated regularly， and soluble sugar， titratable acid， VC， some mineral elements and SOD activity in fruit were measured during mature period， which aimed to provide theoretical basis for producing high-quality apricot fruit.
Materials and Methods
Test materials
Test material was selected from Apricot Demonstration Garden， Shijiazhuang Fruit Research Institute， Hebei Academy of Agriculture and Forestry Sciences. The test apricot variety was 15-year Dafeng Apricot， with plant and line spacing of 4 m×6 m and good growth. Experimental Ca was calcium nitrate （AR）， calcium inhibitor was EGTA （AR）， and they were both prepared into 0.3% of solution by distilled water.
Ca and calcium inhibitor were sprayed in 10 days after flowering period， once per 7 days， which continuously sprayed for three times. Control was spraying clean water， single plant in a district， which repeated for three times.
Methods
Observation of fruit cracking and sample collection： started from June 1， fruit cracking situation was investigated per 7-10 days. If there was fruit cracking， it was recorded and marked. During fruit ripening period， fruits in different treatments were collected and conserved in ultra low temperature freezer， which was used for the determination and analysis of related indexes. Measurement of soluble sugar content： anthrone colorimetry； VC content determination： 2， 6-DCPIP method； measurement of mineral element content： nitric acid-hydrogen peroxide for digestion， atomic absorption spectrometry； SOD activity determination： NBT photoreduction.
Results and Analysis
The impacts of Ca and calcium inhibitor on fruit cracking of apricot
Started from June 1， fruit cracking situation of apricot was investigated （Table 1）. On June 10， fruit cracking started to appear in control and calcium inhibitor treatment， and fruit cracking rate was lower. On June 17， fruit cracking rate quickly increased， while fruit cracking started to appear in Ca treatment， which was 3%. To June 29， fruit cracking rate of calcium inhibitor treatment reached 58%. Above results showed that Ca treatment significantly declined fruit cracking rate， while calcium inhibitor treatment aggravated fruit cracking. It illustrated that Ca content played an important role in fruit cracking of apricot. Liu Huichao et al. thought that calcium inhibitor spraying caused fruit deformation and dehiscence of apple[9]. The research of Nie Guowei et al. showed that fruit cracking of apricot was negatively related to Ca content[7]. The research result was consistent with prior results.
The impacts of Ca and calcium inhibitor on soluble sugar， titratable acid and VC contents in apricot fruit
Seen from Table 2， both soluble sugar and titratable acid in apricot fruit had insignificant difference among different treatments， and ratio of sugar to acid also had insignificant difference. VC content in apricot of Ca treatment increased by 9.2% than control， while VC content in calcium inhibitor treatment declined by 16.75% than control， and they both had significant difference from control. The research of Dong Caixia et al. showed that the mixed solution of 20 mg/L NAA+0.5% CaCl2 spraying flowers， leaves and young fruits of tomato during flowering and young fruit periods could significantly increase Ca and VC contents in fruit[10]. The research results showed that Ca treatment improved VC content in fruit， while calcium inhibitor treatment declined VC content， and VC content was negatively related to fruit cracking of apricot.
The impacts of Ca and calcium inhibitor on mineral nutrient elements in apricot fruit
Seen from Table 3， Ca treatment improved Ca content， while calcium inhibitor treatment declined Ca content， and the difference was significant. Ca treatment declined K content in the fruit， with significant difference from control， while K content in calcium inhibitor treatment had insignificant difference from control. Fe， Cu and Mn contents among different treatments had insignificant difference. In this paper， Ca treatment improved Ca content and declined K content and K/Ca， illustrating that high Ca and lower K was negatively related to fruit cracking. Seen from Table 4， Ca spraying during young fruit period improved SOD and POD activities in fruit， with significant difference， while the difference between calcium inhibitor treatment and control was insignificant. Yang Chunxiang et al. reported that CaCl2 solution spraying in suitable concentration in germination， budding and late flowering stages of nectarine could make SOD activity maintain higher level[8]. The test results showed that Ca treatment improved SOD and POD activities in fruit， which was consistent with prior result.
Conclusions and Discussion
Ca spraying in young fruit period increased Ca and VC contents， SOD and POD activities in apricot fruit， declined K content， K/Ca and fruit cracking. Calcium inhibitor spraying in young fruit period had contrary result to that of Ca treatment， which aggravated fruit cracking of apricot.
Fruit cracking is a kind of physiological disorder in fruit development process， and the lack or accumulation of mineral nutrition is bound to affect the physiological disorder[9]. Many researches show that Ca spraying could decrease fruit crack[11-14]. Ca could combine with pectin substance in cell wall， forming calcium pectate. It increases the elasticity of protoplasm， and enhances pressure resistance and extensibility of cell， anti cracking ability of fruit. Therefore， Ca spraying could ease fruit cracking of apricot. The research results showed that Ca spraying in young fruit period of Dafeng Apricot increased Ca content in fruit， thereby enhancing cells extensibility in fruit and declining fruit cracking of apricot， which was consistent with prior results. Ca inhibitor declined Ca content in fruit， which aggravated fruit cracking.
SOD and POD are important protective enzymes in organism[15-16]. The test results showed that Ca treatment improved Ca content， SOD and POD activities of fruit， thereby easing fruit cracking of apricot， and calcium inhibitor treatment had contrary result.
References
[1] LI KZ.Initial study on fruit cracking mechanism of jujube[J]. Acta Horticulturae Sinica， 1984（2）： 61-62.
[2] WANG XL.Preliminary observation on fruit development anatomy of jujube[J].Chinese Bulletin of Botany， 1974（2）： 161-169.
[3] BANGERTH F. Investigations upon Ca related physiological disorders[J]. Phytopathologische Zeitschrift， 1973， 77： 1， 20-37.
[4] JIANG GL. Cause and prevention of pomegranate fruit crack[J].Xiandai Horticulture ， 2016（2）： 112. [5] CHEN QL，YANG XP，ZHANG JG，et al.The impacts of different treatments on fruit crack and quality of pear[J].South China Fruits ）， 2016， 45（6）： 110-112.
[6] CHEN XH.Influence of bagging on disease and pest of apple and pear fruit[J].Hebei Fruits， 2000（1）： 5， 7.
[7] NIE GW，LI K，TIAN YQ，et al.Correlation of fruit cracking and mineral nutrient content in apricot[J].Journal of Agriculture，2017，7（5）：23-27.
[8] YANG CX，LI XL，GAO DS.Effect of Ca2+ on membrane lipid peroxidation and activity of protective enzymes in nectarine flowers and young fruit under chilling stress[J].Deciduous Fruits，2004， 36（6）：1-3.
[9] LIU HC，HAN ZH.Influence of two calcium inhibitors on development and cell ultrastrcture of young apple fruit[J].Journal of Fruit Science，2002， 19（4）：211-214.
[10] DONG CX，ZHOU JM，FAN XH，et al.Effects of different ways of Ca supplements on the Ca content and forms in mature fruits of tomato[J].Plant Nutrition and Fertilizer Science， 2004， 10（1）： 91-95.
[11] WANG DJ，ZHANG LH.Initial study on rule and control technology of fruit cracking of navel orange[J].South China Fruits，1992，21（2）：17-19.
[12] BAI CH，TIAN SP.Study on Ca of fruit tree[J].Journal of Fruit Science， 1989， 6（2）：121-124.
[13] PENG J.The effect of Ca（NO3）2 and GA sprayed on leaves on the fruit cracking of ‘Nuomici’ Litchi[J].Acta Horticulturae Sinica， 2001（4）： 348-350.
[14] JIANG JK.Study on fruit cracking of Cuiguan Pear[J].South China Fruits， 2003， 32（3）： 62-63.
[15] WANG AG.Oxygen metabolism in plants//YU SW， TANG ZC.Plant physiology and molecular biology[M].Beijing： Science Press，1998.
[16] GUAN JF，SHU HR，ZHANG LC. Regulatory effects of calcium and its antagonists on cell membrane permeability of apple flesh[J].Journal of Fruit Science，2004， 21（5）：402-405.