Reduction In Marketable Yield Research Articles

The Influence of Drip Irrigation or Subirrigation on Zucchini Squash Grown in Closed-loop Substrate Culture with High and Low Nutrient Solution Concentrations

Zucchini plants (Cucurbita pepo L. cultivar Afrodite) were grown during a summer–fall season in closed-soilless systems using a mixture peat–pumice to evaluate the effects of irrigation system (drip irrigation and subirrigation) and nutrient solution concentration (half = 1 dS·m−1 and full = 2 dS·m−1) in terms of substrate electrical conductivity (ECs) using the dilution 1:1.5 media:water method, growth, yield, leaf mineral composition, fruit quality, and mineral solution composition. At the end of the cultural cycle, the highest ECs at the upper (0 to 7.5 cm) and lower (7.5 to 15.0 cm) layers were recorded with subirrigation using a full nutrient solution concentration. The highest plant growth, yield, and leaf macroelements concentration (nitrogen, phosphorus, and potassium) were recorded in both irrigation systems using a full-strength solution, followed by drip irrigation, and finally by subirrigation treatment using a half-strength nutrient solution. Fruit yield, fruit mineral composition (phosphorus, potassium, calcium, and magnesium), and leaf macroelements concentration (nitrogen, phosphorus, potassium, and magnesium) were substantially reduced when the concentrations of macronutrients in the feed solution were lowered to 50% of control. Using half-nutrient solution concentration, the marketable yield reduction was more pronounced with subirrigation (58%) than with drip irrigation (42%). The variation of the macronutrient and EC in the solution during the growing cycle was less pronounced in the subirrigation than with the drip irrigation system, which represents an important aspect for the simplification of the closed-loop management of the nutrient solution.

Potato yield and metabolic profiling under conventional and organic farming

Consumers interest for organic agriculture and environmental-friendly agricultural products is increasing. Nevertheless, cultivation protocols in organic farming are not sufficiently standardized to guarantee product quality stability, a parameter which is critical for further expansion of this niche market. Variable responses in terms of quality and quantity of the harvested product often arise from complex interactions between agronomic and environmental factors. Here we report on the effects of different levels of nitrogen fertilization (0, 50, 150, 200 kg N ha −1) and irrigation regime (50% and 100% replenishment of the evaporation determined using a Class A pan, plus a non-irrigated control) on yield and accumulation of primary metabolites of two potato cultivars (Agria and Merit) grown under conventional and organic farming systems. Organic farming caused a 25% marketable yield reduction with a higher percentage of large tubers under conventional farming, whereas irrigation increased the marketable yield and the percentage of large tubers. Nitrogen fertilization affected the marketable yield and significantly interacted with the irrigation regime in modifying potato yield and quality. Farming protocol, cultivar, irrigation and nitrogen fertilization all affected both amino acid contents and composition with a significant decrease of most essential amino acids in coincidence with highest nitrogen levels. An increased water availability caused an accumulation of reducing sugars in potato tubers only in organic farming, whereas such accumulation was not observed under conventional farming. These results indicate that cultivar-specific genetic determinants and cultivation factors, including the farming system, may strongly and specifically interact to affect important quality parameters of potato tubers. This should be considered to improve quality standards in organic farming.

Weed Control in Processing Tomato (Lycopersicon esculentum) with Rimsulfuron and Thifensulfuron Applied Alone or with Chlorothalonil or Copper Pesticides

Combining herbicides and fungicides can improve production efficiency; however, there is little information on the effect of these mixtures on weed control and processing tomato crop response. Six field trials were conducted from 2002 to 2004 in Ontario to study the effect of rimsulfuron and thifensulfuron applied alone or in combination with metribuzin and with or without chlorothalonil or copper fungicides on processing tomato. There was no visual injury or reduction in marketable yield of processing tomato with rimsulfuron or thifensulfuron alone or when tank-mixed with chlorothalonil or copper hydroxide. Rimsulfuron, thifensulfuron, rimsulfuron plus metribuzin, and thifensulfuron plus metribuzin could be tank-mixed with chlorothalonil without a reduction in weed control. However, efficacy of rimsulfuron and thifensulfuron were reduced when tank-mixed with copper hydroxide. The reduction in weed control incited by adding copper hydroxide was overcome with a low rate (150 g·ha–1 a.i.) of metribuzin for thifensulfuron but not rimsulfuron. Application of rimsulfuron and thifensulfuron alone or with low rates of metribuzin and chlorothalonil could provide tomato growers with a single-pass treatment for the control of troublesome weeds and diseases.

Type of Plant Architecture Can Conceal Fruit During Harvest of Okra

Abstract Fruit concealed by several plant parts are often overlooked during harvest in okra (Abelmoschus esculentus(L.) Moench), causing significant reductions in marketable yield. Effects of plant traits contributing to marketable fruit being missed during harvest were tested in 15 okra cultivars having different plant architectures. Significant correlations between the percentage of overlooked fruit (POF) and several traits were found. There were significant correlations between POF and leaf area, numbers of lateral branches, plant height, number of nodes/ plant and internode length. Correlations between POF and plant height and internode length were negative. Fruit diameter, length, and weight; fruit weight/plant and fruit number/plant; petiole length; and stem diameter were not related to POF. The calculated bias and the coefficient of determination revealed that leaf area accounted for 62% of the variability observed for POF among cultivars; while internode length accounted for only 9% of variability...

Physiological Responses of Pepper to Salinity and Drought

Production of vegetable crops can be limited by saline irrigation water. The variability of crop salt tolerance under different environmental conditions requires species-specific and environment-specific field evaluations of salt tolerance. Data on field performances of vegetable crops grown on soils that have been irrigated with saline water for many years are lacking. In this study we analyzed the long-term effect of irrigation with saline water on soil properties and on responses of field-grown pepper (Capsicum annuum L.) plants in these soils. Yield, gas exchanges, water relations, and solute accumulation were measured in plants grown under three different irrigation treatments: a nonsalinized control (ECw = 0.5 dS·m-1) and two concentrations of commercial sea salt, corresponding to ECw of 4.4 and 8.5 dS·m-1, respectively. In addition, a nonwatered drought stress treatment was included. Irrigation water with an EC of 4.4 dS·m-1 resulted in 46% reduction in plant dry weight (leaves plus stem) and 25% reduction in marketable yield. Increasing the electrical conductivity of the irrigation water to 8.5 dS·m-1 caused a 34% reduction in plant dry weight and a 58% reduction in marketable yield. Leaf and root cellular turgor and net CO2 assimilation rates of leaves in salt-stressed plants decreased along with a reduction in leaf area and dry matter accumulation. High concentrations of Na+ and Cl- in the irrigation water did not significantly alter the level of K+ in leaves and fruit. In contrast, drought stressed plants had higher concentrations of leaf K+ compared to well watered control plants. These results indicate that Na+ and K+ may play similar roles in maintaining cellular turgor under salinity and drought stress, respectively. The regulation of ion loading to the shoots was most likely functionally associated with physiological modifications of the root/shoot ratio that was substantially smaller in salinized vs. drought stressed plants. From an agronomic perspective, irrigation with moderately saline water (4.4 dS·m-1) it is recommendable, compared to no irrigation, to obtain an acceptable marketable yield in the specific environment considered.

025 Pea Leafminer, a New Pest of Leafy Vegetables in Ontario, Canada

A new pest of leafy vegetables was responsible for considerable reductions in marketable yield of several late-season crops in the Holland/Bradford Marsh area (44°5'N, 79°35'W) of Ontario in 1999. The pea leafminer, Lyriomyza huidobrensis, was present in high populations (25/sweep) in fields of celery, Asian crucifer crops, and spinach during the months of August and September. The high populations were associated with extensive leaf mining of celery, root parsley, and edible dandelion. On other crops, including spinach and flat-flowering Chinese cabbage (Brassica chinenesis group var. utilis) damage consisted of stippling of the leaves, as a result of feeding and possibly oviposition, but no leaf mining. The stippling was extensive and rendered these crops unmarketable. An other Asian crucifer, Chinese broccoli (Brassica alboglabra) exhibited high numbers of stipples on the leaves, but very low numbers of mines. The leaves of red beets exhibited a low incidence of mines, not enough to affect yield. This is the first report of the pea leafminer affecting field vegetables in this area and causing crop losses. Pictures of the pest and symptoms of damage to the crops will be presented.

5537759 Process for drying useful materials for detergents and cleaning products using superheated steam: Raehse Wilfried; Fues Johann-Friedric; Koch Otto; Schmidt Joerg-Martin, Duesseldorf, Germany assigned to Henkel Kommanditgesellschaft auf Aktien

Field experiments were conducted to evaluate the effectiveness of a tomato fruitworm, Helicoverpa zea (Boddie), management program where insecticide application was made only when fruitworm eggs were detected on tomato foliage. Fruit damage and number of insecticide applications were compared between the egg scouting program and a standard fruitworm management program where insecticides were applied on a weekly schedule. On average, 59 and 43% fewer insecticide applications (for esfenvalerate and Bacillus thuringiensis, respectively) were required in the egg scouting program, compared with the weekly spray program, without any reduction in marketable yield. The average seasonal insecticide cost savings associated with the use of the egg scouting program were $US109.33 and $US93.33 per ha for esfenvalerate and B. thuringiensis, respectively. When scouting was used, average net returns, considering machinery and labor costs, were $US146.45 and $US164.33 per ha higher for esfenvalerate and B. thuringiensis, respectively.

Treatment decisions based on egg scouting for tomato fruitworm, Helicoverpa zea (Boddie), reduce insecticide use in tomato

Field experiments were conducted to evaluate the effectiveness of a tomato fruitworm, Helicoverpa zea (Boddie), management program where insecticide application was made only when fruitworm eggs were detected on tomato foliage. Fruit damage and number of insecticide applications were compared between the egg scouting program and a standard fruitworm management program where insecticides were applied on a weekly schedule. On average, 59 and 43% fewer insecticide applications (for esfenvalerate and Bacillus thuringiensis, respectively) were required in the egg scouting program, compared with the weekly spray program, without any reduction in marketable yield. The average seasonal insecticide cost savings associated with the use of the egg scouting program were $US109.33 and $US93.33 per ha for esfenvalerate and B. thuringiensis, respectively. When scouting was used, average net returns, considering machinery and labor costs, were $US146.45 and $US164.33 per ha higher for esfenvalerate and B. thuringiensis, respectively.

Short-Term exposure to low temperature in the fall affects field performance of seed tubers

Field trials were conducted in Alberta and Ontario with Norchip, Norland, Russet Burbank, Sangre and Superior potato cultivars to determine response to short-term exposure of seed tubers to below freezing temperatures in the fall. Exposure of the dormant seed tubers to −-1 C for up to 48 hours did not affect the yield or growth characteristics of the cultivars. However exposure of seed tubers to −-5 C temperatures for 6 or 12 hours caused marked (P < 0.05) reductions in marketable yield, marketable tuber number, maturity and vine size. Exposure to −-5 C for periods longer than 12 hours resulted in severe freezing damage and subsequent decay of most of the tubers.

Yield and Yield Component Response of Eight Potato Genotypes to Water Stress

The differential tolerance to moisture stress among potato (Solanum tuberosum L.) genotypes may be associated with differences in sensitivity during the ontogeny of yield development. This study was undertaken to determine the effect of a wide range of moisture stresses on the yield and components of yield of eight genotypes (‘Acadia Russet’, ‘Bintje’, ‘Jemseg’, ‘Kennebec’, ‘Raritan’, ‘Russet Burbank’, ‘Sable’, and ’Shepody’). The genotypes were subjected to three levels of soil moisture tension in 1983 (−30, −60, and −90 kPa) and four in 1984 (−30, −60, −90, and −120 kPa) at Vauxhall, Alberta on a Cavendish sandy loam (Brown Chernozemic) (fine‐loamy, mixed, frigid Ultic Haploxeralf). A mathematical model based on the method of path analysis was used to study the relationship between the components of yield and the overall response of the final tuber yield to moisture stress. Moisture stress treatments caused marked (P &lt; 0.01) reductions in marketable yield, tuber number per stem and average tuber weight. Mainstem number was not affected. The genotypes ✕ stress interaction was significant (P &lt; 0.05) in an analysis of variation (ANOVA) carried out over 2 yr. While analysis of the yield data using the model demonstrated that in general genotypes are very sensitive to moisture stress at both tuber initiation and at the tuber sizing growth stages, the greatest variability amongst genotypes in response to stress occurred at tuber sizing. Shepody, Russet Burbank, and Sable showed a strong sensitivity to stress in the tuber initiation phase while Jemseg, Acadia Russet, and Kennebec were more sensitive at tuber sizing. The study demonstrates differences in the structure of the response of the genotypes to moisture stress, measured in terms of the components of tuber yield, and indicates the importance of this information to ensure efficient moisture management.

Physiology and yield of field‐grown Brassica oleracea L. exposed to acidic fog

SUMMARYField‐grown Brassica oleracea L. ev. Emperor (broccoli) plants were exposed to a range of treatments with simulated acidic fog in open‐field plots to examine the effect of fog chemistry on yield and growth, and to determine whether alterations in yield or growth were related to the development of foliar injury and/or the inhibition of net photosynthesis. Simulated fogs (i.e. pH values of 1.76, 2.23, 2.72, 3.22 or 5.48) with a liquid water content of 0.20–0.25 g m−3 were applied twice weekly for 10 weeks. Applications of pH 1.76 fog caused significant yield reductions (37%) relative to pH 5.48. Leaf dry weight responses were more sensitive to fog chemistry than yield. Leaf dry weight was significantly inhibited by 53, 25 and 9% in the pH 1.76, 2.23, and 2.72 fog treatment groups, respectively.The depression of yield by fog of pH 1.76 was closely correlated with the development of foliar injury and the inhibition of net photosynthesis on a percentage basis. Plants exposed to pH 2.23 or 1.76 fog consistently displayed amounts of injury ranging from 5 to 7% or 20 to 31%, respectively, whereas plants exposed to pH 2.72 fog or higher exhibited less than 5% injury throughout the study. Whole‐study average rates of net photosynthesis were significantly depressed by pH 1.76 fog (30% lower). The inhibition of net photosynthesis was coincident with increases in both mesophyll and stomatal resistances to CO2, but the ratio of mesophyll to stomatal resistance was not significantly altered.These findings provide evidence that repeated exposures to highly acidic fog (pH 1.76 or 2.23) may cause significant reductions in marketable yield and/or growth of B. oleracea, but substantive adverse effects would not be expected from exposures to fog of lower acidic strength. Although the inhibition of net phososynthesis in B. oleracea by acidic fog was coincident with decreased yield, reduced rates of CO2 assimilation appear to be due to the development of foliar injury (i.e. reduced photosynthetically active leaf area per plant) rather than a specific alteration in mesophyll or stomatal resistance to CO2.

Título en español.

Se estabecieron siembras bimestrales durante abril, junio, agosto, octubre y diciembre de 1972 y febrero de 1973 con el propósito de evaluar el efecto de la época de siembra y de la edad a la cosecha sobre la producción comercial y la calidad de los tubérculos de cuatro variedades de yautía. Las variedades y las edades al momento de la cosecha estudiadas fueron las siguientes: Kelly, cosechada a los 8 y 10 meses; Blanca del País, Morada y Rascana cosechadas a los 10 y 12 meses. Los resultados indican que la mejor época para la siembra de yautías es la comprendida en el período entre la primera semana de abril y la primera de agosto. Después de estos meses baja drásticamente el rendimiento. Las variedades que produjeron los rendimientos mayores fueron la Morada y la Rascana cosechadas a los 12 meses. En general, todas las variedades se beneficiaron de la extensión del período de crecimiento. Sin embargo, la Rascana fue la más favorecida al aumentar significativamente el número de tubérculos comerciales. Aunque el retrasar la cosecha hace que la textura de los tubérculos sea algo más blanda, los factores de época de siembra y edad a la cosecha no afectaron significativamente los atributos de textura, apariencia, color y sabor de los tubérculos.

Unfavourable thermal conditions of air at the turn of the 20th and 21st centuries reducing crop productivity of pickling cucumber (Cucumis sativus L.) in Poland

Growing influence of anthropopressure and irregular changes in weather conditions necessitated conducting agroclimatic research into the assessment of plant cultivation risk caused by unfavourable meteorological conditions, including thermal conditions of air. The goal of the work was to assess the risk of pickling cucumber field cultivation in Poland caused by an unfavorable course of air temperature (Ta) in the period from sowing to the end of harvesting at the turn of the 20th and 21st centuries. To accomplish the goal, the study used data describing growth, development and crop productivity of cucumber in the years 1966-2005. Data was used concerning the described thermal conditions with the average Ta in the whole growing season of the analysed plant. The data came from 28 experimental stations and 53 meteorological in Poland. The effect of Ta in the growing season (sowing-end of harvesting) on the total and marketable yield of cucumber was evaluated. The study used curvilinear regression analysis with two variables. The highest risk of cucumber’s cultivation caused by unfavorable thermal conditions of air was recorded in south-western, south-eastern, and also northern and north-eastern Poland. In these high risk areas reduction in the total yield oscillated between 15% and even over 21% below the multi-annual average. Reduction in the total yield occurred with frequency from 40% to above 80%. In south-western and south-eastern Poland, a reduction in the marketable yield amounted to maximally above 15%. A marketable yield reduction occurred with a frequency of from 50% to above 70%.

Assessment of vigour and uniformity in Brussels sprouts

1. Measurements were made of stem length, leaf number, leaf size, total yield and marketable yield on two varieties of Brussels sprout, on inbred lines derived from them, and on hybrids produced by crossing the inbred lines of the two varieties. 2. Three sets of such measurements were taken at different periods in the growing season. The standard errors of plot totals decreased with increasing plant maturity, but the standard errors of the within-plot variances were not affected. 3. Inbreeding depression varied considerably in degree, both between different inbred lines and between different characters in the same line, and ranged from a 5 per cent. reduction in number of leaves to a 58 per cent. reduction in marketable yield, as compared with the parent non-inbred varieties. 4. Hybrid vigour varied in a similar manner, but all hybrid families gave yields which exceeded that of the highest yielding parent variety. 5. In every hybrid family studied, the increase in the marketable yield, as compared with the mean of the parent varieties, was greater than the increase in any other character including total yield. It is suggested that this was the result of selection during inbreeding, for uniformity of desirable sprout quality. 6. Analysis of the within-plot variances of the characters measured suggested that uniformity for plant and leaf size characters had not been markedly changed by inbreeding. 7. The contrast between increased uniformity for sprout quality and lack of detectable change in uniformity for plant and leaf size characters is attributed to different rates of approach to homozygosis at different loci as a result of selection. 8. Inbred lines can combine to produce hybrid families with yields superior to those of the non-inbred parent varieties. Work is continuing on both the breeding and assessment of inbred lines, and on the technical problems involved in the production of hybrid seed in commercial quantities.