Optimization of cultivation medium for enhanced production of antifungal metabolites by Streptomyces hygroscopicus

Antifungal potential of Streptomyces hygroscopicus metabolites was tested against the isolates of Colletotrichum spp., obtained from rotten apple fruits. Experimental factorial design and response surface methodology were employed to optimize medium composition and enhance antifungal components productivity by S. hygroscopicus. Results of optimization suggest that the optimal medium composition is (g/L): glycerol (13.92), yeast extract (5.00), phosphates (0.63), CaCO₃, (3.0), NaCl, (3.0), MgSO₄, (0.5). Further research was performed to validate the obtained results and confirm their applicability in planta on artificially inoculated apple fruits. The obtained efficacy after 14 days of incubation was 99.3% against Colletotrichum acutatum and 99.8% against Colletotrichum gloeosporioides. Application of supernatant of S. hygroscopicus cultivation medium, produced under defined conditions, in biological control of apple rot could offer safe and healthy apple fruits on the market, while simultaneously helping to solve the problem of waste glycerol disposal in the biodiesel industry.     

苹果（Malus pumila）幼果钙素吸收特性与激素调控

采用田间试验并结合#+45Ca示踪及植株分析等方法研究苹果幼果钙素吸收特性及激素对其过程的调控方式。结果表明,施于叶片的钙极少向果实转移,钙应有针对性直接施至幼果上,适宜的施钙时期为幼果形成1个月内,CaCl#-2喷施的适宜浓度为0.5%。果面施钙显著增加了苹果单果重,改善了果实品质。IAA、GA和NAA均可促进果面钙运往果实内,并导致2%HOAc提取钙与5%HCl提取钙组分增加,IAA虽可促进大量的树体钙向果实转移,却会导致果实钙含量过高,品质变差;GA和NAA则不能夺取树体内的钙,对果实品质无不良影响。     

Advance of apple and pear tree full bloom dates in response to climate change in the southwestern Cape, South Africa: 1973-2009

Studies from throughout the world have demonstrated that tree phenophases are becoming earlier in spring and are closely associated with rising temperatures. Despite many such studies from the Northern Hemisphere, similar comparative work has not been forthcoming from the Southern Hemisphere or from Africa. In addition, few studies have demonstrated the possible role of changes in precipitation and associated soil moisture to driving fruit tree phenophases. Here we provide changes of mean full bloom dates for three apple Malus domestica (Golden Delicious, Sayaka, Granny Smith) and one pear Pyrus communis (Bon Chrétien) cultivars in the southwestern Cape of South Africa. These phenological changes are correlated with temperature and precipitation changes in the same region between 1973 and 2009. Significant early spring (August/September) temperature increases of +0.45 °C/decade are associated with a mean full bloom advance of 1.6 d/decade over the last 37 years. Golden Delicious apple trees have the strongest sensitivity (+4.2 d/°C) to climate change in the region, whilst Granny Smith apple trees have the lowest (+2.4 d/°C). Although winter and early spring rainfall has also decreased over this time, such decreases are not significant. However, significant correlations are found for both temperature and rainfall when comparing with the mean full bloom dates, and it is proposed that both variables operate synergistically to influence mean full bloom dates in the southwestern Cape.     

An efficient laser sensor system for apple impact bruise volume estimation

Fruit are subjected to several external loads during processes from the orchard to the market, which result in bruising and therefore, quality loss. In this study, we developed a system based on a line laser light source and light detector for a rapid and efficient estimation of the bruise volume of apples (Malus domestica Borkh L. cv. Starking Delicious) dropped from a certain height onto a steel impact plate. We measured two parameters, namely rise time and dwell time, extracted from response signals generated by the proposed system during the impact test. These parameters are related to contact time, showing how long the fruit remains in contact with the impact plate. The experiments were conducted at six different drop heights and two different temperatures. It was found that there was a strong relation with coefficients of determination of more than 0.93 between bruise volume and dwell/rise time, in which the bruise volume decreased with the increasing rise time/dwell time as a power function. Furthermore, the results showed that warm apples developed greater bruise volume than cold fruit, and the estimated regression lines and curves for cold fruit had higher coefficients of determination than those of warmer fruit.     

Effect of gamma irradiation on storability of apples (Malus domestica L.)

The aim of this study was to investigate the effect of gamma irradiation on storability of the two main apple varieties, Golden Delicious and Starking, in Syria. The experiments were performed in 1995 and 1996. Fruits were irradiated with 0, 0.5, 1.0 and 1.5 KGy. Irradiated and unirradiated fruits were stored at 1 to 2 °C and under a relative humidity of 80 to 90%. Weight loss and spoilage due to physiological disorders and fungal diseases were evaluated throughout the different storage periods. Firmness, coloration and pH values were estimated immediately after irradiation. The results showed that, in both varieties, gamma irradiation increased the weight loss after 45 days of storage in apples gathered in 1995 but not in the 1996 season. After 180 days of storage, gamma irradiation had different effects on weight loss depending on the growing year and variety, and increased fungal spoilage. Application of gamma irradiation prevented the growth of Aspergillus niger and the formation of skin scald in Golden Delicious fruits. Immediately after treatment, gamma irradiation increased the softening of fruits, changed their color from green to yellow and decreased the pH value of the juice.     

近红外（NIR）光谱法测定完整苹果糖的含量

介绍一种快速分析完整苹果糖分的新方法──近红外光谱法。在波长９１０ｎｍ附近，高、中、低糖含量的二阶导数光谱之间有明显差异，该波长选作定标的第一波长。经９１０ｎｍ、８８４ｎｍ、８４３ｎｍ、９９１ｎｍ四波长线性回归分析，其相关系数为０．９８４，标准误差为０．３６０，检验时的标准误差为０．４５０，离差为０．１１。ＮＩＲ光谱法在实际应用中可满足完整苹果糖含量的测定精度。     

Volatile production by ‘Golden Delicious’ apples is affected by preharvest application of aminoethoxyvinylglycine

The effect of AVG application on the quality and volatile production of ‘Golden Delicious’ apples, grown in Chihuahua Mexico, was evaluated. AVG (125 g AVG/ha) was applied on apple trees four weeks before harvesting. Apples were harvested 176 days after full bloom and stored at 8 °C for 35 d. Quality parameters and volatile compounds were periodically evaluated. AVG application retarded color changes, and preserved acidity of apples during storage. Ethylene synthesis was also delayed by AVG. Control apples presented higher total soluble solids content than AVG-treated apples at the end of cold storage. Volatile production was affected by AVG application, especially in the case of esters and alcohols, which presented 59% and 33% lower values in AVG-treated apples at the end of storage. A higher concentration of aldehydes was observed at harvest time in AVG-treated apples; however, no difference was observed between treatments during storage. Higher correlations between ethylene production and aldehydes and alcohols were found in control apples (0.98, and 0.98, respectively), than in AVG-treated apples (0.6 and 0.90, respectively). AVG application on ‘Golden Delicious’ apples conferred a variety of benefits, such as delaying maturation, maintaining color, and reducing changes in acidity and total soluble solids. However, AVG treatment negatively affects the production of some volatile compounds.     

陕西苹果产区果实重金属含量水平调查

对陕西省苹果产区5个县的13个苹果园的套袋富士、未套袋富士及秦冠共39个苹果样品中的铜、铬、汞和铅4种重金属含量水平进行了检测。结果显示,铜、铬、汞的检出率均达到100%,铅的检出率为94.6%;4种重金属的含量水平均未超过无公害食品苹果的卫生标准;不同县区苹果中铬、铜、汞和铅4种元素含量水平均未达到显著差异;同一果园中3个样品间均不存在显著差异。     

Cropping effects on the loss of apple fruit firmness during storage: The relationship between texture retention and fruit dry matter concentration

Firmness is a primary measure of apple fruit texture, the key determinant of eating quality of apples. Despite the well developed understanding of the process of firmness loss in storage, there is very limited information concerning pre-harvest and at-harvest causes of the variation in fruit quality in the marketplace. The objective of the present study was to investigate the respective roles that the factors of time and intensity of crop thinning, fruit size and fruit dry matter concentration (DMC) each may have in determining fruit firmness of ‘Royal Gala’ apple at harvest and during storage. Loss of firmness during storage of all thinning treatments and of fruit size and DMC categories was described by a bilinear equation. Time of thinning did not influence any aspect of fruit softening during air storage at 0.5 °C. Comparing the crop loads, a lower crop load (100 fruit per tree) resulted in firmer fruit at harvest. The loss of firmness during storage associated with crop load occurred because fruit from the lowest crop load softened more rapidly during the second slow phase of softening. Fruit firmness was positively correlated with fruit size where larger fruit were slightly firmer than smaller fruit at harvest but not after storage. The softening profiles of different sized fruit were similar except for a class of extremely small fruit, which appeared to soften more rapidly during the second slow softening phase of storage. Both at-harvest and post-harvest fruit firmness were influenced by fruit DMC. Fruit firmness at harvest increased significantly as fruit DMC increased from 13% to above 16%. Despite having significantly different initial firmness, all fruit classes with DMC higher than 13% softened at a similar rate during both the initial rapid and second slow softening phases and the transition between the two phases occurred after the same time in storage. In contrast, fruit with very low DMC, less than 13%, had a greater rate of softening in the second phase. These results indicate that variation in fruit firmness at harvest and after storage is influenced by processes that affect and alter fruit DMC during fruit development. In this respect crop load control, which is used to improve fruit size, was also an important factor in altering fruit DMC, thereby affecting firmness at harvest and after storage. Furthermore, the effects of DMC on fruit firmness were independent of fruit size.     

苹果果皮蜡质组分的GC-MS分析

为进一步给研究苹果果皮蜡质组分同苹果贮藏特性之间的关系提供有效的技术手段,以蜜脆和嘎拉苹果为试材,建立一套适合苹果果皮蜡质的气相色谱-质谱(GC-MS)分离和鉴定方法。通过硅胶和氧化铝柱将氯仿提取物分为非极性、弱极性和极性3个馏分,再进行GC-MS分析,并比较分析品种之间的组分。蜜脆鉴定出20种烷烃,18种脂肪酸,18种酯类和4种烯烃。嘎拉鉴定16种烷烃,21种脂肪酸,19种酯类和5种烯烃。蜜脆和嘎拉烷烃均以C29烷和C27烷为主,脂肪酸以饱和脂肪酸为主,嘎拉和蜜脆的烷烃和脂肪酸分别表现出奇数碳优势和偶数碳优势。不同品种间组分存在差异,嘎拉烷烃组分中缺少nC16、nC17、nC32和nC33烷烃,蜜脆中质量分数最高的脂肪酸为饱和脂肪酸十六烷酸,而嘎拉中质量分数最高的脂肪酸为不饱和脂肪酸亚油酸。酯类组分差异最大,仅有6种共有组分。