Distribution of nutrients in the root zone affects yield,quality and blossom end rot of tomato fruits

Summary

Tomato plants (Lycopersicon esculentum Mill. `DRK') were grown hydroponically in two experiments to determine the effects of nutrient concentration and distribution in the root zone on yield, quality and blossom end rot (BER). The plants were grown in rockwool with their root systems divided into two portions. Each portion was irrigated with nutrient solutions with either the same or different electrical conductivity (EC) in the range 0 to 6.dS m^±1. In both experiments, fruit yields decreased as EC increased from moderate to high when solutions of equal concentration were applied to both portions of the root system. However, higher yields were obtained when a solution with high EC was applied to one portion of the root system and a solution of low EC to the other portion. For example, the fresh weight of mature fruits in the 6/6 treatment was only 20% that of the 3/3 treatment but the 6/0 treatment had a yield that was 40% higher. The reduction in yield in the high EC treatments was due to an increase in the number of fruits with BER and smaller fruit size. BER increased from 12% to 88% of total fruits as EC increased from 6/0 to 6/6 and fruit length decreased from 67.mm to 52.mm. Fruit quality (expressed as titratable acidity and soluble solids) increased as EC increased. In summary, high yields of high quality tomatoes with minimal incidence of BER were obtained when one portion of the root system was supplied with a solution of high EC and the other portion with a solution of moderate or zero EC.     

Sap volatile components in relation to susceptibility of anthracnose and Aspergillus rot of mangoes (Mangifera indica L.)

Sap burn injury and postharvest diseases are major causes of mango fruit quality deterioration, resulting in considerable postharvest losses in many countries. Susceptibility of selected cultivars of mango in Sri Lanka to sap burn injury and the incidence of anthracnose and Aspergillus rot of mango were examined in this study. Volatile components of non-aqueous (oil) phase were investigated using GC-MS, and artificial inoculation studies were carried out to assess disease resistance with Colletotrichum queesnlandicum (KC 820802) and Aspergillus niger (KC 820801). It was observed that the popular ‘Karuthakolumban’ and ‘Willard’ mangoes with high sap flow at harvest and high sap burn incidence were more susceptible to sap burn injury compared with ‘Chembaddan’ and ‘Ambalavi’ mangoes. Cultivar variations in susceptibility to Aspergillus rot of mangoes are reported for the first time in this study, where ‘Willard’ mangoes were more resistant to Aspergillus rot than other cultivars. The sap exudates of ‘Ambalavi’ and ‘Karuthakolumban’ mangoes were observed to contain the preformed antifungal compounds 5-pentadecyl resorcinol and 5-(Heptadeca-8,11- dienyl) benzene1,3-diol, with variety ‘Ambalavi’ showing a high resorcinol level. These cultivars were found to be resistant to anthracnose disease. These results suggest that presence of sap volatiles is cultivar dependent and could be used to identify cultivars resistant to postharvest diseases and sap burn.     

苹果品种对轮纹病抗性的鉴定

对富士、金冠、红星、嘎拉、华冠和GS4354、GS4772等17个品种(系)进行了枝干轮纹病田间发病状况调查,通过对其1年生枝的田间和温室接种进行了抗性鉴定,同时研究了枝条皮孔密度和大小与轮纹病抗性之间的关系。结果表明:秦冠、北之幸、GS43543品种(系)对枝干轮纹病具有较强的抗性;富士、华冠、金冠、红星等品种易感病;1年生枝条皮孔密度和皮孔大小与抗病性之间存在显著的负相关。皮孔密度与其直径之积可作为1个形态指标,用于对枝干轮纹病抗性的简单评价。     

番茄疫霉根腐病的发生与防治技术

番茄疫霉根腐病,俗称＂烂脖根死棵病＂.近几年此病发生危害有逐年加重趋势.尤其是冬春茬和早春茬番茄,在4-5月份结果初期发病严重,死棵多,甚至毁秧绝产.此病发生期与辣椒疫病发生期基本相同,其危害程度也不相上下.     

Evaluation of garlic cultivars for salinity tolerance

Salinity tolerance in garlic cultivars was studied in pots. A 50% yield reduction occurs at 5.60-7.80 dS m1, depending on genotype. It was estimated that if soil salinity exceeds 1.70 dS m_l, the mean garlic yield declined by 1.68% per unit increase in soil salinity.     

The pattern of flavan-3-ols in relation to scab resistance of apple cultivars

Amounts and types of flavan-3-ols in leaves and fruit skins of scab-resistant and susceptible apple cultivars were determined by the combined use of HPLC and CRD (chemical reaction detection). The latter is necessary because the UV absorption spectra of flavanols are generally uninformative. Resistant cultivars had higher quantities of fla- van-3-ols in leaf tissue and fruit skin than susceptible ones: levels were 6.5 fold higher in leaves and 3 fold higher in fruit skins. Approximately twice the number of different fla- van-3-ols were found in leaves and fruit skin of the resistant group than in the susceptible one.     

波兰樱桃产业发展概况

介绍了波兰的樱桃产量、面积和分布,主要品种和栽培模式,为中国的樱桃产业发展提供了系统的产业信息。     

Growth rates of glasshouse tomato fruit in relation to final size

The individual growth rates of the first five tomato fruits on 25 trusses of similar age within a crop grown in commercial glasshouse conditions were assessed from anthesis to ripening during April and May. Final size of fruit at ripening was proportional to the maximum rate of increase in fresh weight, about 40 d after anthesis, and related to the maximum rate of increase in diameter, between 15 and 20 d after anthesis, even though ripe fruit fresh weight varied from 20 g to over 100 g. On any one truss these fruit ripened within the same week, regardless of fruit size and prevailing growth rate. These findings suggest that final size was related to the peak fruit growth rate rather than the duration of development. A high growth rate late in development did not delay fruit ripening. The implications for recent continuous measurements of the diameter growth rate in young fruit are discussed.     

Deposition of calcium compounds in tomato fruit in relation to calcium transport

The deposition of calcium in tomato fruit grown at a range of salinities (electrical conductivities between 3 and 17 mS cm“1), with or without IAA-transport inhibitor treatment, was investigated. Calcium (Ca) in the flesh and pulp of tomato fruit was sequentially separated into four fractions: FI soluble in water, FII soluble in 2.5 mol dm“3 NaCl, Fill soluble in 2% acetic acid and FIV soluble in 5% HC1. In mature fruit, grown at 3 mS cm“1, more than half the Ca was in FI, and the Ca concentration was higher in the pulp than in the flesh. FII and Fill each contained less than 20% of the Ca, and the Ca concentration was higher in the flesh than in the pulp. In general, salinity reduced the concentration of Ca in all fractions and slightly altered the proportional distribution of Ca in fractions. The deposition of calcium in young fruit, grown at 3 and 8 mS cm“1, was highest in FII in the flesh or in FI in the pulp. When 45Ca was supplied to detached fruit, the patterns of45 Ca distribution in the fractions were similar to that of total Ca. Treatment with an IAA-transport inhibitor, CME, reduced both the uptake and transport of 45Ca. While the amount of 45Ca in all fractions was significantly reduced by CME, the proportional distribution of 45Ca among fractions was not affected substantially. Although the proportional deposition of Ca in different fractions was not significantly affected by either salinity or CME, further reduction of the intrinsically low deposition of Ca in FII of distal pulp caused by these factors may be the cause of blossom-end rot in tomato fruit.     

Sucrolytic activities in cherry tomato fruits in relation to temperature and solar radiation

A study has been made concerning the influence of two environmental factors (temperature and solar radiation) on sugar content and sucrolytic activity in cherry tomato fruits during the crop cycle. For this, Solanum lycopersicum cv. Naomi plants were grown in an experimental greenhouse. Three fruit samples were taken over the entire production period: the first sampling at the beginning of harvest [85 days after transplanting (dat)], the second at mid-harvest (160 dat), and the third at the end of harvest (229 dat). The values for temperature and solar radiation peaked in the third sampling, coinciding with an increase in lipid peroxidation, without lowering yield with respect to previous samplings. Regarding the sugar content in the cherry tomatoes, our results showed that the increase in temperature and solar radiation diminished the sucrose content at 229 dat and raised the hexoses (glucose and fructose) as well as starch content, produced primarily by the enzyme sucrose synthase. On the contrary, the rest of the enzymes responsible for sucrose degradation, acid and neutral invertases, showed no notable changes in their activity at the end of the crop cycle. In short, our results suggest that the increase in sucrolytic activity, induced mainly by sucrose synthase under these conditions, contributes to the mechanisms of antioxidant defense by supplying precursors (glucose and fructose) of antioxidant compounds in order to restrict the massive accumulation of ROS and thereby avoid the appearance of cell necrosis and reduce yield losses.     

Growth and water relation responses to salinity stress in halophytic seashore paspalum ecotypes

This study was to assess selection criteria for salt tolerance in halophytic seashore paspalum (Paspalum vaginatum Swartz) ecotypes, and to determine influence of salinity on water status. Nine seashore paspalums exhibiting the widest range of salinity tolerance were grown in a greenhouse using nutrient/sand culture. Comparative salinity tolerance was determined by measuring shoot, root, and verdure dry weights at six salinity levels (1.2–49.7 dS m⁻¹). Threshold EC_w (electrical conductivity of water), EC_w50%, EC_w25%, and leaf firing (LF50) were also measured. Total water potential (Ψ_w), solute potential (Ψ_s), turgor pressure (Ψ_p), and relative water content (RWC) were determined as measures of water status across salinity levels. Based on the number of times in the top (best) statistical category for growth measurements, SI 93-2 and HI 101 were the most salt-tolerant ecotypes, while Adalayd was least tolerant. Results indicated that comprehensive assessment of salt tolerance using different tissues across salinity levels up to EC_w50 were desirable and repeatable in halophytic seashore paspalums. The criteria EC_w50%, EC_w25%, and LF50 were also useful in ranking of salt tolerance, but threshold EC_w was not reliable in halophytic turfgrass. Shoot Ψ_w and Ψ_s decreased continuously in all ecotypes as salinity increased. Trends in shoot growth of salt-tolerant SI 93-2 and HI 101 and least tolerant Adalayd paralleled responses of shoot Ψ_p with the more tolerant ecotypes maintaining more favorable Ψ_p and growth. Among parameters of water relations, shoot Ψ_w and Ψ_p were found to have the largest effects, which accounted for 82% and 22% of variations of shoot and root growth of seashore paspalums, respectively.     

The effect of split-root salinity stress on tomato leaf expansion,fruit yield and quality

Summary

A crop-scale experiment between March and October 2000 investigated the effects of split-root salinity stress and rooting volume on the expansion of leaves, fruit yield and quality in two standard round fruited cultivars of tomato (Lycopersicon esculentumMill) Solairo and Espero, grown in rockwool. To implement the treatments, a split-root method was utilized whereby different levels of salinity (expressed as EC), adjusted by the addition of NaCl, was administered to two halves of a root system. The split-root high EC (2.8/8.0 dS m^–1) treatment enhanced fruit quality by increasing the concentrations of sugar, acid, total soluble solids and reducing the incidence of visual defects such as uneven ripening and gold-spot. Split-root high EC did however reduce leaf area that corresponded with low K concentration in the leaf tissue. The split-root method utilized doubled the rooting volume compared with the standard single rockwool slab, but this extra rooting capacity had no detectable effect on leaf expansion, yield or fruit quality. Although there was little impact on yield for ten weeks after the imposition of the high EC split-root treatment, mean reductions in weekly yield occurred thereafter and were of the order of 9 and 13% for ‘Solairo’ and ‘Espero’ respectively through to the end of the experiment. The fall in yield was due, in part, to a decrease in fruit size. Whilst water uptake was reduced it was unclear how the effects on leaf growth and fruit yield were mediated in the shoot. Possible processes that coordinate responses to root-zone salinity stress are discussed. The potential use of the split-root system in commercial production is considered.     

Relationship between lodging,morphological characters and yield of tomato cultivars

Experiments were carried out in the early and late seasons in the rain-forest zone of Nigeria to find out the relationship between lodging, morphological characters and yield of tomato. Lodging was associated with plant height, leaf area, number of branches/plant and fruit yield. Lodging was more severe in the wet early season than in the late season.     

Relationship between ADH activity,ripeness and softness in six tomato cultivars

Fruit from six tomato cultivars were harvested at progressive stages of ripeness. Fruit softness was measured together with the activity of the alcohol dehydrogenase (ADH) enzyme in the pericarp tissue. The rate of increase in ADH activity in the ripening fruit was found to be strongly correlated (r=0.970) with the rate of softening of the fruit suggesting that induction of ADH activity in the fruit was possibly a function of the softening of the fruit rather than a direct function of ripening. As the ADH enzyme is involved in several aspects of flavour development in the ripening tomato fruit, in particular the regulation of accumulation of some aldehydes and alcohols, a correlation between fruit softening and activity of the enzyme has important implications regarding flavour development in tomato fruit of firm or soft varieties.     

Effect of interplanted rice on the growth of tomato in deep solution culture and on the response to salinity

Summary

Tomatoes were grown for 66 d in deep solution culture (a) without aeration, (b) with interplanted rice and (c) with air bubbled through the solution, in factorial combination with two electrical conductivities (4 and 8 mS cm^?1). Root growth was seriously restricted in the poorly aerated solutions (a) and (b). Interplanted rice stimulated shoot growth compared with the un-aerated treatment, and increased the total dry weight, leaf area and fruit yield (fresh weight) by up to 26, 34 and 22% respectively. The total dry weight of plants grown with rice was only 60% of that of the aerated ones but the area of corresponding upper leaves was 73%. Water and nutrient uptake were reduced by poor aeration but, after allowing for the uptake by the interplanted rice, only the uptakes of P and Ca by tomatoes in that treatment were significantly higher than those of the un-aerated plants. The higher salinity reduced growth and the uptake of nutrients. No interaction between aeration and salinity was found.     

Photosynthesis of field-grown Arracacha (Arracacia xanthorriza Bancroft) cultivars in relation to root-yield

There has been limited research on measuring potential differences in leaf gas exchange of Arracacha (Peruvian parsnip, Arracacia xanthorriza Bancroft) cultivars, as affected by different environments, as well as its relation to storage root-yield. The present paper reports field measurements of leaf CO₂ assimilation rates (A) for five contrasting cultivars grown at two different high-altitude locations. Using a design of plots chosen at random with three repetitions, commercial root production was determined in the two locations at different altitude (1580 and 1930 m). Daily leaf gas exchange was repeatedly monitored with a portable open-mode infrared gas analyzer at different times in both locations during the growth cycle. Root-yield, leaf area and dry weight were measured. Significant differences in leaf photosynthetic rate and in specific leaf area (SLA) were observed among cultivars. Cultivars with high SLA, had high CO₂ assimilation. Mean (A_n) and total (A_tot) of CO₂ assimilation and SLA were significantly correlated with storage root-yield across cultivars and locations. The three cultivars with the greatest commercial root production also had the highest maximum values for A and the highest specific leaf area, indicating that these two parameters can be used to select for highly productive cultivars of A. xanthorriza.     

Utilization of correlation network analysis to identify differences in sensory attributes and organoleptic compositions of tomato cultivars grown under salt stress

In tomato production, salt stress is applied to improve the fruit quality. The change in sensory attributes and organoleptic compositions in salt-stressed tomato fruits have been extensively studied; however, little is known about their interaction with each other. Correlation network analysis provides a visual representation of biological systems and useful knowledge for metabolic data analysis of tomato fruits. The aim of this study is to identify the cultivar differences in sensory attributes and organoleptic compositions of tomato fruits grown under salt stress and to elucidate their interaction among different cultivars using correlation network analysis. Salt stress was applied by adding 100 mM NaCl to the nutrient solution. Fruits were harvested at red-ripe stage and used for the evaluation of sensory attributes such as sweetness, sourness, umami, and tomato like, and organoleptic compositions such as sugar, organic acid, amino acid, and sodium ion contents. Almost all of the sensory attributes and organoleptic compositions of the fruit were significantly high in salt-stressed cultivars compared to non-stressed cultivars, and significant differences were also observed among cultivars. The correlation network analysis of the control fruit showed that compared to other traits, sugar is one of the key traits for improvement of tomato fruit quality based on high connectivity and betweenness centrality. In contrast, a high degree of positive connectivity was not observed between organoleptic compositions and sensory attributes in the salt-stressed fruit network. These results indicate that the relationship between sensory attributes and organoleptic compositions in fruits were different between the control and salt-stressed cultivars, suggesting that the salt-stressed fruit may have a different circuit of relationship compared to control. Furthermore, based on the increase ratio (salt stress/control) network results, we suggest that the increased sugar, organic acid, and amino acid contents may have contributed to the salt stress-induced enhancement of sensory attributes.     

Concurrent action of salinity and water stress on leaf gas exchange and water relations in tomato

Tomato plants (Lycopersicon esculentum Mill.) grown in pots were irrigated for four weeks with 0.04,0.08,0.12 molai NaCl solutions and a control solution. Half the plants in each salt treatment were water stressed for five days. Single leaf gas exchange at near ambient C02, water consumption and plant water relations were measured. Both salt and water stress reduced growth, water potential and gas exchange rates. Well watered plants were only slightly stressed by a salt concentration of 0.04 molai, while plant growth continued at a concentration of 0.08 molai. Short-term water stress imposed greater stress than long-term salt stress; carbon exchange rate (CER) was partially limited by stomatal closure in the case of water stress and by mesophyll limitation with longer-term salinity treatments. Osmoregulation in response to salt stress did not impart particular tolerance to transient water stress.     

杧果蒂腐病菌对多菌灵的抗药性测定及其杀菌剂筛选

对来自海南3个地区的86个杧果蒂腐病菌(Botryodiplodia theobromae Pat.)菌株进行了对多菌灵的抗药性测定,结果表明,杧果蒂腐病菌群体中存在着对多菌灵抗性的群体。采用生长速率法进行了23种杀菌剂对4株杧果蒂腐病菌的室内毒力测定,通过EC50值、EC90值及与多菌灵的交互抗性等的综合分析,结果表明,作为防治杧果蒂腐病的首选药剂有咪鲜胺锰盐、丙环唑、氟硅唑、咪鲜胺、异菌脲、苯醚甲环唑、戊唑醇、腈菌唑、吡唑醚菌酯和井冈霉素10种杀菌剂,可选杀菌剂还有百菌清和代森锰锌。杧果蒂腐病菌除对多菌灵产生抗性外,还对甲基硫菌灵、醚菌酯和烯唑醇3种杀菌剂产生了抗药性。通过交互抗性分析,多菌灵、甲基硫菌灵和烯唑醇3种杀菌剂之间存在交互抗性,而醚菌酯与井冈霉素之间存在负交互抗性。为了避免杧果蒂腐病菌对某种杀菌剂产生抗药性,建议上述可选用杀菌剂交替使用。     

Genetics of resistant to tomato yellow leaf curl virus in tomato

The genetics of resistance to tomato yellow leaf curl virus (TYLCV) were studied in TYLCV-resistant lines developed by crossing wild species of Lycopersicon pimpinellifolium, L. hirsutum and L. peruvianum resistant to TYLCV with susceptible L. esculentum cv. Special Back. Crosses between TYLCV-resistant lines derived from the same wild species produced progenies similar to their parents in their level of resistance. However, progenies from interspecific crosses showed greater resistance than either parent suggesting that the genes for TYLCV resistance contributed by different wild species are probably not the same (non-allelic). The gene action for TYLCV resistance also varied with the source of resistance. Analysis of F₁, F₂ and BC populations for lines derived from L. pimpinellifolium showed that resistance to TYLCV in these lines is a quantitative trait with some dominance.