Freezing and Frost Damage of Potato Plants: a Case Study on Growth Recovery,Yield Response,and Quality Changes

The relationship between the severity of natural freezing and frost damage (FFD) and the observed growth recovery and field production of Superior potatoes (Solanum tuberosum L.) was investigated under screen house conditions. Potato plants were damaged by accidental freezing and frost during the early phase of shoot growth, 40 days after planting in highland summer crop areas in Korea. The observations of FFD were classified visually into “severe” (>75%), “moderate” (50%), “mild” (<25%), and “no FFD”, based on the percentage of the area of the shoots which was damaged. The early vegetative growth recovery, in terms of groundcover, was reduced as the level of FFD increased. At 28 days after a freezing and frost damage (DAFF), the potato plants with mild or no symptoms had produced more groundcover than the plants with moderate or severe symptoms. At 35 DAFF, groundcover was the same across all levels of severity, at nearly 100%. Despite the slower canopy development, plants with FFD achieved a higher fresh shoot weight and total chlorophyll content, whereas physiological growth indices such as photosynthetic rate and stomatal conductance of leaves were not different among levels of FFD at 60 DAFF. The number of lateral stems and days to tuberization increased significantly as the level of FFD increased; however, the harvest index, the number of tubers per plant, and seed tuber production were all reduced in plants with severe FFD. In addition, the tubers from plants with severe FFD had an increased ratio of length to width and 40% more tuber eyes than tubers from undamaged plants. The elongated tubers also showed an increase in cell division, demonstrated by higher numbers of cells in the cortical zones. The aforementioned measurements were obtained from natural event and led to a deduction that Superior has a capacity to recover from FFD, unless the plants were severely damaged (>75%) early in the season.     

Physical, Chemical, and Antioxidant Activity Characterization of Pitaya (Stenocereus pruinosus) Fruits

Fruits with red and orange flesh of the columnar cactus pitaya (Stenocereus pruinosus) were studied to evaluate physical characteristics, total soluble solids, betalains and soluble phenols content, and antioxidant activity. Fruits had, in average, weight of 179.0 g, 9.8 °Brix, 9.4 % carbohydrates, 1.25 % protein, 0.11 % ethereal extract, 0.60 % crude fiber, and 0.62 % ash. Also, fruits resulted rich in Fe (22.8–27.8 mg/kg). Hue angle and contents of betacyanins, betaxanthins (μg/g dry sample), and total soluble phenols (mg GAE/g fresh sample) were 19.8°, 2860.0, 3210.0, and 1.6 in the red material, and 28.9°, 470.0, 2670.0, and 1.2, respectively, in the orange fruit. The antioxidant capacity was higher in the red material, since the ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)) technique reported 1090.6 and 735.4 μmol of Trolox equivalents/g fresh flesh in red and orange fruits, respectively, while the oxygen radical absorbance capacity (ORAC) assay reported 7.84 and 5.16 μmol of Trolox equivalents/g fresh flesh, respectively. The chromatographic profile showed five betalains in red fruits, but only four of them were observed in those orange fleshed.     

Plant growth strategies of Thymus vulgaris L. in response to population density

Thymus vulgaris L., known as common thyme, is a perennial subshrub native to the Mediterranean region. The use of the extracts and herb of thyme plants as antibacterial, antioxidant, natural food preservative and in cosmetic industry has increased the economic importance of this medicinal crop worldwide. Agricultural practices have an influence on growth and yield of thyme plants. Therefore, an experiment was undertaken to determine the effects of three intra-row spacing (15, 30 and 45 cm) and four harvesting times (vegetative, beginning of blooming, full blooming and fruit set) on plant growth and herbage biomass of thyme in 2007 in the research farm of Shoubak University College in the southern part of Jordan. The experiment was a split plot in randomized complete block design with four replicates. Apart from the experiment in 2007, measurements taken on the 15th of November in 2008 were treated as an independent experiment irrespective of harvesting stage. The effects of spacing were not significant for all the parameters measured in 2007. Intra-row spacing in 2008 had significant effects (P < 0.05) on plant height, canopy diameter, herbage fresh and dry weight and number of leaves on long shoots. Its effect on dry weight of shoots, fresh and dry weight of long shoots, number of long shoots, root depth, leaf area and specific leaf area was very significant (P < 0.01). Results of this study indicated that thyme plants grown using 15 cm planting space and harvested at the fruit set stage in 2007 had the highest fresh and dry weight of shoots. The highest dry weight of shoots, herbage fresh and dry weight was also obtained in 2008 in 15 cm spacing. Closer spacing resulted in significantly taller plants that exhibited higher shoot:root ratio and, therefore, plants grown using 15 cm intra-row spacing had a better use of light and accumulated more biomass compared to plants in wider spacing. The differentiation between long shoots and short shoots throughout plant development in 2007 suggests a specialization in carbon gain along different times in the growing season. Swings observed for shoot:root ratio, leaf area and specific leaf area were related to thyme growth. The decrease in specific leaf area between vegetative and full bloom stage indicated that leaves became thicker as part of an adaptive mechanism to the surrounding environment. Information obtained from growth parameters, leaf area and specific leaf area in particular, could be related to essential oil production in leaves of thyme plants.     

Selection indices for improving selection efficiency in Indian mustard

In Indian mustard (Brassica juncea L. Czern & Coss), a major oilseed brassica crop, oil yield is the ultimate trait of economic value, which is determined by seed yield (SY) and oil content (OC). SY, the end product of many complex biological processes, is influenced by many traits, such as plant height (PH), branch number, siliqua number, seed weight, seed size and pod length. It is difficult to accurately select for high-yielding genotypes based exclusively on SY, neglecting other yield-determining traits in commercial breeding programs. Therefore, it is desirable for breeders to simultaneously improve several traits of economic importance, most of which are quantitative in nature. The purpose of the present study was to develop selection indices for simultaneous selection of multiple quantitative traits to enhance selection efficiency of the mustard breeding program of Punjab Agricultural University (PAU) located in Abohar, Punjab. A set of 487 diverse mustard genotypes, comprising germplasm accessions of Indian and European origin, advanced breeding lines, landraces, and cultivars, was evaluated using an alpha lattice design for 2 years (2015–16 and 2016–17) at the Regional Research Station of PAU, Abohar, District Fazilka (the major mustard-growing region of the Punjab state). Data on PH, main shoot length (MSL), number of primary branches (NPB), number of secondary branches (NSB), number of siliquae on main shoot (NSMS), siliqua length (SL), number of seeds per pod (NSP), 1000-seed weight (TSW), SY on a plot basis and OC were recorded. To compute selection indices, economic weights, as determined via path coefficient analysis, were assigned to major yield-determining traits. Out of eight recorded agronomic traits, four traits, viz., NSMS, TSW, NSB and NPB, had larger direct effects on SY than other traits, and hence were assigned relative economic weights of 0.60, 0.20, 0.12 and 0.08, respectively. Selection indices were computed using different combinations of traits via Kang_SASPath computer program. When seven traits were used in a selection index (PH, NPB, NSB, NSMS, SY, TSW and MSL; or PH, NPB, NSB, NSMS, SY, TSW and OC), expected genetic advance (GA)at 5% selection intensity was about the same (9.55; selection efficiency or SE = 163% compared with selection based on SY alone).The GA was 9.46 (SE = 161%)for five traits, viz., NPB, NSB, NSMS, SY and TSW; and 9.30 (SE = 159%)for four traits, viz., NPB, NSB, NSMS, and TSW. These GAs were compared with the GA for SY only, which was 5.90 (benchmark; SE = 100%). We concluded that simultaneous selection based on multiple traits was always more efficient than selection based on SY alone. As there was only a small difference between the GA based on four traits (SE = 161%) and GA based on seven traits (SE = 163%), we suggest that mustard breeders use the parsimonious combination of four traits, viz., NPB, NSB, NSMS, and SY, to enhance SY and, consequently, oil yield in mustard.     

Induction of lignin and pathogenesis related proteins in dragon fruit plants in response to submicron chitosan dispersions

Chitosan is capable of triggering the induction of defence responses of the plants. This study was carried out to investigate in vitro and in vivo antifungal activity of submicron chitosan dispersions and also to determine the mechanism of induced resistance in dragon fruit plants by strengthening of cell wall and production of pathogenesis related proteins. Highest inhibition in radial mycelial growth (90.2%) was obtained by 600 nm droplet size at 1.0% chitosan concentration. None of the emulsifiers showed any antifungal effect during in vitro studies. Field studies showed the reduction of 22% disease incidence and 66% disease severity in anthracnose on dragon fruit plants treated with 600 nm droplet size as compared to control plants after one month of assessment. Lignin contents in cell wall of dragon fruit plants increased 2 folds in plants treated with 1.0% chitosan at 600 nm droplet size while 11 and 10 folds increase in β-1,3-glucanase and chitinase activity, respectively was also recorded in the plants inoculated with Colletotrichum gloeosporioides. The accumulation of lignin and higher level activity of pathogenesis related proteins in response to submicron chitosan dispersions may bolster in mounting effective resistance against the devastating disease of anthracnose.     

Antioxidant activity of some Jordanian medicinal plants used traditionally for treatment of diabetes

Medicinal plants are being used extensively in Jordanian traditional medicinal system for the treatment of diabetes symptoms. Twenty one plant samples were collected from different Jordanian locations and used for antioxidant evaluation. The level of antioxidant activity was determined by DPPH and ABTS assays in relation to the total phenolic contents of the medically used parts. The most frequently used plant parts as medicines were fruit, shoot and leaves. The total phenolic contents of methanol and aqueous extracts, from plants parts, ranged from 6.6 to 103.0 and 3.0 to 98.6 GAE mg g(-1) of plant part dry weight, respectively. DPPH-TEAC of the methanol extracts of plants parts were varied from 4.1 to 365.0 mg g(-1) of plant dry weight versus 0.6 to 267.0 mg g(-1) in aqueous extracts. Moreover, the mean values of ABTS*- (IC50) varied from 6.9 to 400.0 microg dry weight mL(-1) ABTS in methanol extracts versus 9.8 to 580.5 microg mL(-1) in aqueous extracts. According to their antioxidant capacity, the plants were divided into three categories: high (DPPH-TEAC > or = 80 mg g(-1) ), (i.e., Punica granatum peel, Quercus calliprinos leave, Quercus calliprinos fruit, Cinchona ledgeriana and Juniperus communis leave), moderate (DPPH-TEAC range 20-80 mg g(-1)) (i.e., Salvia fruticosa shoot, Crataegus azarolus stem, Crataegus azarolus leave, Varthemia iphionoides shoot, Artemisia herba-alba shoot, Thymus capitatus shoot, Morus nigra leaves and Arum palaestinum leaves) and low antioxidant plants (DPPH-TEAC < 20 mg g(-1)), (i.e., Matricaria aurea shoot, Artemisia judaica shoot, Teucrium polium shoot, Pinus halepenss pollen grains, Sarcopoterium spinosum root, Crataegus azarolus fruit, Inula viscose shoot and Achillea fragrantissima shoot). The antioxidant activity of these plant's extracts and their potential rule in radical scavenging agreed with their potential use by Jordanian population as a traditional anti-diabetic agents.     

Simulated Gastrointestinal Digestion,Bioaccessibility and Antioxidant Capacity of Polyphenols from Red Chiltepin (<Emphasis Type="Italic">Capsicum annuum</Emphasis> L. Var. <Emphasis Type="Italic">glabriusculum</Emphasis>) Grown in Northwest Mexico

Chiltepin, a wild chili mostly used in different traditional foods and traditional medicine in Northwest Mexico, represents a source of polyphenols. However, studies about the bioaccessibility of polyphenols as a parameter to measure the nutritional quality and bioefficacy of them in the fruit after consumption are scarce. Chiltepin showed phenolic acids and flavonoids contents between 387 and 65 μg/g, respectively. Nevertheless, these values decreased after the digestion process. Before digestion, gallic acid, 4-hydroxibenzoinc acid, chlorogenic acid, caffeic acid, p-coumaric acid, quercetin and luteolin were the main polyphenols found in chiltepin by HPLC-DAD and confirmed by FIA-ESI-IT-MS/MS. Gallic and chlorogenic acids were non-detected in the gastric phase, while only p-coumaric acid (5.35?±?3.89 μg/g), quercetin (5.91?±?0.92 μg/g) and luteolin (2.86?±?0.62 μg/g) were found in the intestinal phase. The bioaccessibility of phenolic acids, flavonoids, and total polyphenols after the intestinal phase was around 24, 17 and 23%, respectively. Overall, results indicated that release of polyphenols from chiltepin fruit might be affected by the food matrix and gastrointestinal conditions due to the low bioaccessibility values observed.     

‘金都1号’火龙果果实生长发育规律研究

以红肉火龙果桂红龙系列‘金都1号’为试验材料，研究测定从果实谢花后第1天到果实成熟采收时，果实果形指数、鲜重、干重及含水量的变化过程。结果表明：火龙果成熟时果形指数1.14，主要表现为近圆形，花后8～23 d为果实的快速生长期，平均增长速率为20.5 g/d，快速生长期结束后(果实开始转红)，果皮厚度下降，果皮鲜重也随之下降。     

壳聚糖对玉米幼苗生长及生理生化活性的影响

采用浸种实验,研究不同分子量壳聚糖对玉米种子萌发、幼苗生长及生理生化活性的影响。结果表明,5种壳聚糖均能显著提高玉米种子的发芽率、发芽势、发芽指数、活力指数和幼苗的根长、芽长和株鲜重,提高幼苗的叶绿素含量和可溶性蛋白含量,增加幼苗的根系活力,有效诱导超氧化物歧化酶(SOD)和过氧化物酶(POD)的表达,显著提高酶活性。平均分子量5 000的壳聚糖对种子萌发和幼苗生长促进效果较好,分子量为3 000的壳聚糖对幼苗生理活性及酶活力提高最大。     

Potassium silicate and chitosan application for gray mold management in strawberry during storage

The objective of this study was to investigate the effect of silicon and chitosan as alternative controls for postharvest rot of strawberries (gray mold) caused by Botrytis cinerea. Chitosan and potassium silicate applications were performed at the preharvest stage using the following treatments: chitosan once a week; potassium silicate once a week; potassium silicate once a week + chitosan once a week; and without application. An additional variable was introduced at postharvest, with one-half of the total fruit harvested from each plot dipped in chitosan and the other half not dipped in chitosan. Potassium silicate alone was not effective for rot control. Fruits from plants that received the chitosan application showed 64% less area under the rot progress curve (AURPC) than fruits from plants that were not treated with chitosan. Harvested fruits that were chitosan dipped showed 48% less AURPC than fruits that were not treated at postharvest. Chitosan application in the field and at postharvest is a promising strategy for the management of postharvest strawberry rot.     

Correlation of Rutin Accumulation with 3-O-Glucosyl Transferase and Phenylalanine Ammonia-lyase Activities During the Ripening of Tomato Fruit

In tomato, the predominant flavonoid is quercetin-3-rutinoside (rutin). In this study, we aim to investigate the phenylalanine ammonia-lyase (PAL) and the quercetin-3-O-glucosyl transferase (3-GT) reactions in the formation of rutin during tomato fruit ripening. Tomatoes of the Moneymaker variety at different development stages (green, breaker, turning, pink, red, and deep red) were divided into flesh and peel fractions. In each sample, both the content of rutin and the enzymatic activities for PAL and 3-GT were recorded. The highest activities of PAL were recorded in the peel of turning fruit (3,000 μkat/mg fresh weight). In fruit flesh, maximal activity was observed in red fruit (917.3 μkat/mg). For both tissues, PAL activity strongly decreased at the final (deep red) fruit stage. The activity of 3-GT in peel peaked in the turning fruit stage (50.7 pkat/mg), while in flesh maximal activity (33.4 pkat/mg) was observed in green fruit, which rapidly declined at the turning stage. Higher levels of rutin were detected in the tomato peel compared to the flesh part with the highest level being found at the green stage. The relation of PAL and 3-GT activities to rutin content is also evaluated.     

壳聚糖处理对采后建阳桔柚果实品质和贮藏特性的影响

探讨不同浓度壳聚糖处理对采后建阳桔柚果实在(10±1)℃下贮藏的生理特性、营养品质和贮藏特性的影响。结果表明：与对照果实相比,壳聚糖处理能降低建阳桔柚果实的呼吸强度,延缓果皮细胞膜透性的升高,抑制果实表面色调角h°值下降,果肉能保持较高的可溶性固形物、可滴定酸度、总糖、维生素C和类胡萝卜素含量,减少建阳桔柚果实失重和腐烂,保持较高商品率。其中以稀释500倍壳聚糖处理的保鲜效果最佳,果实商品率一直保持在95%以上,感病指数控制在0.1以下,而且果肉基本无汁胞枯水现象,贮藏后期果实的失重率可控制在5%以内。因此认为,稀释500倍壳聚糖处理是保持采后建阳桔柚品质、延长其保鲜期的有效方式。     

Biological Activities of Extracts from Chinese Bayberry (Myrica rubra Sieb. et Zucc.): A Review

Chinese bayberry (Myrica rubra Sieb. et Zucc.) is a subtropical fruit tree native to China and other Asian countries, and culture of this Myricaceae plant has been recorded in Chinese history for more than 2000 years. Bayberry fruit is delicious with attractive color, flavor, and high economic value. Compared with other berries, bayberry fruit is a rich source of cyanidin-3-glucoside (C3G, e.g., 64.8 mg/100 g fresh weight in ‘Biqi’ cultivar), which accounts for at least 85 % of the anthocyanins in the fruit. Bayberry is also a plant with high medicinal value since different organs have been used historically as folk medicines. Research efforts suggest bayberry extracts contain antioxidants that exhibit bioactivities counteracting inflammation, allergens, diabetes, cancer, bacterial infection, diarrhea and other health issues. Bayberry compounds have been isolated and characterized to provide a better understanding of the chemical mechanisms underlying the biological activities of bayberry extracts and to elaborate the structure-activity relationships. As the identification of compounds progresses, studies investigating the in vivo metabolism and bioavailability as well as potential toxicity of bayberry extracts in animal models are receiving more attention. In addition, breeding and genetic studies of bayberry with high accumulation of health-benefiting compounds may provide new insight for the bayberry research and industry. This review is focused on the main medicinal properties reported and the possible pharmaceutically active compounds identified in different bayberry extracts.     

Application of bioactive coatings based on chitosan for artichoke seed protection

Artichoke seeds suffer attacks of various fungi that result in a decreased yield. Coatings based on chitosan were used as an antifungal agent and for enhancing the germination and quality of artichoke seeds. The effect of formulation (chitosan molecular weight, presence or absence of Span 80, pH), and thickness (number of coating layers) on seed germination (G%), fungi activity and vegetative growth were studied. Results indicated significant differences between treatments on seed germination. It was observed that all chitosan treatments reduced the number of type of fungi and increased plant growth. Chitosan with lower Mw gave better results both from microbial and germination point of view. In addition results indicated that treatments including chitosan and TMTD increased significantly G% and plant growth of artichoke seeds and produced a decrease in fungi contamination.     

香蕉枯萎病高抗品种‘中蕉9号’营养特性的评价

为在巴拿马枯萎病高抗品种‘中蕉9号’推广应用中合理施肥和进行有效的养分管理。以大田正常管理条件下的‘中蕉9号’为试材,采用整株肢解法研究‘中蕉9号’香蕉根、茎、叶、果穗4个器官的干物质氮磷钾养分累积及分配规律,以探讨其养分综合管理技术。结果表明,‘中蕉9号’单株鲜重、干重平均为(145.35±6.42)、(18.18±0.70) kg/株,干物质不足整个植株鲜重的1/8,干物质中灰分仅占8%。4个器官鲜重大小依次是茎（93.53 kg/株）>果穗（33.38 kg/株）>叶（14.93 kg/株）>根（3.51 kg/株）。干物质累积分配规律和鲜重一致,即茎>果穗>叶>根。茎的干重为8.44 kg/株,其中干物质主要分配在假茎中（76%）,球头仅占24%。叶的干重为2.77 kg/株,干物质在叶片中的分配比例是56%,在叶柄中的分配比例是44%。果穗的干重为6.71 kg/株,其中果实的干物质分配比高达94%,果轴的仅占6%。对整株香蕉而言,约2/3的干物质分配到根茎叶中,即2/3的光合产物用于根茎叶的生长,而只有约1/3的光合产物用于果实生长。平均而言,‘中蕉9号’每株累积吸收纯氮116.89 g、纯磷23.67 g、纯钾510.29 g,氮磷钾的吸收比例为1.00:0.20:4.37。氮磷钾吸收累积量在4个器官中的分配大小依次是：茎>果穗>叶>根;根、茎、叶、果穗中的N:P:K比例分别为1.00:0.21:6.82、1.00:0.25:7.38、1.00:0.13:1.96、1.00:0.21:3.10,可见4个器官中,茎部吸收累积氮磷钾总量以及钾的比例最大。‘中蕉9号’根茎叶特别是茎中干物质和钾的吸收累积量远大于巴西蕉是其养分管理值得重视的一个特点。根据‘中蕉9号’生物量和氮磷钾吸收累积分配规律,参考巴西蕉的研究结果,本研究提出‘中蕉9号’的养分管理的建议：孕蕾前应适当控制养分水分供应,限制茎叶徒长和养分消耗;肥料N:P₂O₅:K₂O的比例可参考巴西蕉的营养特性,在孕蕾前采用2.0:0.5~1.0:1.0,在孕蕾至抽蕾期,采用1.0:0.5:2.0,抽蕾后至收获前采用1.0:0.5:2.5~3.0的配方。为了做到更好的养分管理和实现化肥高效利用,‘中蕉9号’茎和叶中积累如此多的碳水化合物和钾以及如何促进他们运输到果实是值得研究的课题。     

Effect of Genotype on the Sprouting of Pomegranate (<Emphasis Type="Italic">Punica granatum</Emphasis> L.) Seeds as a Source of Phenolic Compounds from Juice Industry by-Products

Pomegranate (Punica granatum L.) fruits are used mainly by the juice industry, for which seeds are a by-product to be disposed of, though they could potentially be a source of bioactive compounds. In this work, germination (total germination percentage, G; mean germination time, MGT; time to reach 80% of germination, TG80; seedling shoot length, fresh weight and dry matter), and nutritional value (total phenolics, TP; total flavonoids, TF; total non-tannins, TNT; antioxidant activities) of pomegranate seeds and sprouts were determined on four commercial pomegranate cultivars (Akko, Dente di Cavallo, Mollar de Elche and Wonderful). Seeds were removed from ripe fruits and incubated in plastic trays containing sterile cotton wetted with distilled water. Sprout shoots were harvested when they reached the complete cotyledon expansion, i.e., the ready-to-eat stage. Akko showed the best germination performance (G = 98%; MGT = 14 days after sowing, DAS; TG80 = 16 DAS), followed by Mollar de Elche. Sprouting dramatically increased TP, TF, TNT and antioxidant activity in all genotypes, with the highest values recorded in Mollar de Elche and Dente di Cavallo. Overall, based on germination performance, Akko and Mollar de Elche would be the best cultivars for sprouting. Sprouting pomegranate seeds appears to be a suitable way of utilizing by-products of the juice industry to obtain bioactive compounds.     

Varietal differences in tiller and panicle development determining the total number of spikelets per unit area in rice

ABSTRACT

Rice varietal differences were compared between japonica type (JAT) and indica type (INT) and between panicle number type (PNT) and panicle weight type (PWT) in terms of tiller and panicle development. Rice varieties PNT-JAT Hinohikari, PWT-JAT Akenohoshi, PNT-INT IR36, and PWT-INT Takanari were used in the field experiments. Tiller bud formation and tiller leaf emergence occurred slightly later in the PWT than in the PNT varieties. These parameters occurred slightly earlier in the INT than in the JAT varieties. The maximum number of tillers was greater in IR36 than in Takanari, Hinohikari, and Akenohoshi. The number of panicles per unit area (PN) was greater in IR36 and Hinohikari than in Akenohoshi and Takanari. The widths of the shoot apical meristem (SAM) just before panicle initiation were in the order of Akenohoshi > Hinohikari = Takanari > IR36. The number of spikelets per panicle (SN) was in the order of Takanari = Akenohoshi > IR36 > Hinohikari. In conclusion, the PWT varieties, which had relatively wider SAM, presented with the promotion of main shoot development and the suppression of tiller development. Consequently, PN decreased and SN increased in PWT varieties. INT varieties presented with the promotion of tiller and rachis branch development, which resulted in increases in both PN and SN. These developmental factors may determine varietal differences in the total number of spikelets per unit area.     

Effect of High Hydrostatic Pressure on the Physiology of Manila Mango

Manila mangoes (Mangifera indica L.) have sensory characteristics that make them attractive for consumption as a fresh fruit. A large portion of the annual yield of this fruit is infested by the Mexican fruit fly (Anastrepha ludens), adversely impacting the quality of the crop. Hence, it is necessary to develop economically viable postharvest treatments to reduce the damage caused by this insect. Currently, high hydrostatic pressures are used to guarantee the safety of many processed foods. The objective of this work was to assess the effects of high hydrostatic pressure on mangoes at their physiological maturity. High hydrostatic pressures were applied to mangoes at three levels: 50, 100 and 200 megapascals applied for four different time periods (0, 5, 10 and 20 min). Physiologically mature mangoes were more resistant to changes in response to the pressure of 50 MPa. Reduction of physiological activity by application of high hydrostatic pressure opens a new avenue for the research on treatments intended to enhance preservation of whole fresh fruit.     

不同比例红蓝LED灯对蔬菜育苗的补光效应

为解决华南地区冬春季节蔬菜育苗缺光现象,采用不同比例红蓝光组合的LED灯（红 ∶ 蓝=7 ∶ 3,7R3B;红 ∶ 蓝=8 ∶ 2,8R2B;红 ∶ 蓝=9 ∶ 1,9R1B）进行补光,以自然光为对照,探讨不同光质的LED灯补光对苦瓜、豆角、茄子和辣椒育苗的效应。结果表明：不同的红蓝光组合LED灯补光对苦瓜、豆角、茄子和辣椒育苗具有一定的促进作用,其中对苦瓜幼苗的鲜重、地下部分干物质积累、叶绿素含量以及根系活力具有显著的促进效应;对豆角幼苗地下部分干物质积累、叶绿素含量以及根系活力具有显著的促进效应;对辣椒和茄子的形态指标和生理指标均有显著的促进效应,辣椒育苗的最适壮苗光源为9R1B,茄子育苗的最适壮苗光源为8R2B。     

Yield response of okra, Abelmoschus esculentus (L.) Moench to leaf damage by the flea beetle, Podagrica uniforma Jacoby (Coleoptera: Chrysomelidae)

Yield-related response of okra plants, Abelmoschus esculentus (L.) Moench, to artificial infestation of the flea beetle (Podagrica uniforma Jac.) at different densities (0, 5, 10, 20, 30, and 40 pairs per cage) was studied in screen house and field experiments. In both experiments, increase in beetle density resulted in a significant reduction (P < 0.05) in fruit production, fruit length, fruit width, fresh fruit weight, number of seeds per fruit, 100 seed weight and fresh fruit yield. In addition, higher densities caused more dry matter accumulation in the seeds than in the husk of okra fruits. Compensation was noticed at the 5- and 10-pair levels of infestation in some of the variables measured. Fresh fruit yield reduction was more than 50% when beetle density was increased beyond 20 pairs per cage in both experiments. The lowest density of P. uniforma at which significant reduction (P < 0.05) occurred in fresh fruit yield per cage, when compared with the control, was the 20-pair level, representing the damage threshold of the beetle at which initiation of control measures would be justified. Regression analysis indicated that flea beetle density was linearly associated with fruit damage and fresh fruit yield. Also, chi-square analysis showed that the models derived from the screen house and field experiments were not significantly different (P < 0.05) from each other, and either could be used for prediction purposes.