Delayed Harvest Time Research Articles

Effect of Fruit Harvest Time on the Nutritional and Agronomic Quality of Oleaginous Citrullus lanatus Seeds

Oilseeds of Citrullus lanatus are highly prized in African societies for their nutritional and socio-economic importance. In an attempt to improve their yield, remaining very low mainly due to lack of good nutritive and germinative quality seeds, the effect of fruit harvest time was studied. After growing plants of ʺwlêwlêʺ cultivar on Nangui Abrogoua University experimental site, fruits were harvested at six different times [15, 20, 25, 30, 35 and 40 days after anthesis (DAA)] then fermented to produce seeds for germination test concerning agronomic aspect and biochemical analysis for nutritional quality. Agronomically, results showed that delaying harvest time (from 15 to 40 DAA) significantly (P < 0.001) improved fruit weight (from 512.20 to 760.50 g) and their seed content (from 71.75 to 230.70 seeds/fruit), as well as size (from 10.69 to 11.42 mm) and weight (from 5.16 to 6.37 g) of dry seeds what lead to their optimum viability (89.50%). Nutritionally, apart from ash which didn’t vary, C. lanatus seeds reached their highest levels of flavonoids (0.03 mg/100g) and tannins (0.022 mg/100g) at 15 DAA, followed by protein (30.66%), lipids (56.60%) and vitamin C (2.25 mg/100g DM) ones at 35 days while dehydrating to reach the lowest moisture content (5.51%). Hence, this variety seeds reach their nutritional maturity earlier, already at 35 DAA, while their optimal germination quality occurs later at 40 DAA.

Nitrogen fertilisation and harvest time on biomass production and composition of tall wheatgrass in Mediterranean marginal conditions

Among several cool-season grasses, tall wheatgrass (Elymus elongatus (Host) Runemark) has been recently identified as a promising energy crop for Mediterranean low productive areas under rainfed conditions. The influence of annual N top dressing applications (0, 30, and 80 kg ha−1) on the production, composition and combustion quality properties of tall wheatgrass biomass was studied for 9 years on marginal land. The effect of harvest time was evaluated from early summer until late winter with three cultivars of tall wheatgrass (‘Alkar', ‘Jose', and ‘Riparianslopes').Biomass production grew with increasing N input and spring rainfall. The 80 kg N ha−1 treatment provided mean dry matter production of 4.1 Mg ha−1 yr−1 but elevated biomass N levels from 8.5 to 10.0 g kg−1. An autumn harvest in mid-October led to dry matter losses of 16%, and reduced moisture (−48%), ash (−24%), N (−39%), Cl (−61%), S (−24%) and ash K2O (−41%) levels. Delaying harvest time until late winter greatly improved fuel quality, reducing N by 51%, and Cl and K by 80–85%, while increasing deformation and flow temperatures by 370 °C and 240 °C, respectively, but led to matter losses of 36–48%. The differences found in the chemical composition of tall wheatgrass across years and N applications up to 80 kg N ha−1 yr−1 are not expected to be of any practical relevance if this type of biomass is utilised in combustion processes. On the contrary, a harvest delay can improve quality properties for combustion.

Effect of Fruit Harvest Time and Fermentation Methods on Seed Viability and Seedling Vigour in Oleaginous Citrullus lanatus

Aims: In an attempt to improve the yields of Citrullus lanatus’s wlêwlê oilseed cultivar, generally low due to the lack of good germination seeds, the effect of fruit age at harvest and fermentation methods were studied. The present study is a contribution to the improvement the African oleaginous Cucurbits seed production system by optimizing the date of harvest combined to seed fermentation methods through enhancement of seed germination and seedling vigor.
 Study Design: Seedling vigor was evaluated on farm trial using five completely randomized blocks represented by seedbeds constituting each, one replication.
 Place and Duration of Study: The trials were carried out from July to December 2020, at the experimental farm of the Nangui Abrogoua University in the district of Abidjan, southern of Côte d'Ivoire between 5°17' and 5°31' North latitude and between 3°45' and 4°31' West longitude.
 Methodology: Fruits from grown plants were harvested at five different times 20, 25, 30, 35 and 40 days after anthesis (DAA)] and seeds fermented following four methods fermentation at ambient air (SFA); fermentation in a plastic bag exposed at ambient air (SFB); fermentation in plastic bag buried in 30 cm depth (SFD) and control or non-fermented (NF)]. Seeds from these 20 treatments (5 harvest time × 4 fermentation methods) were sown for viability tests in laboratory and seedling vigor in the field.
 Results: Analysis of variance (ANOVA) showed that delaying harvest time (from 20 to 40 DAA) significantly (P < .001) improved fruit weight (from 512.20 to 760.50 g) and its seed content (from 71.75 to 230.70 seeds/fruit), seed size (length: 10.69 to 11.42 mm and width: 5.31 to 5.90 mm) and weight (5.16 to 6.37 g) as well as their viability (from 67.75 to 89.50 %). Moreover, in spite of facilitating seed extraction, all three fermentation methods (SFA, SFB and SFD) significantly improved seed viability and seedling vigor compared to control (NF) seeds. The highest agronomic performance (seed viability and produced seedling vigor), was obtained with fermentation under closed and deep confinement (SFD), followed by the closed confinement (SFB) and then by the open environment (SFA). Positive interaction (harvest time × fermentation method) revealed that the best performance was achieved with later harvested seeds (40 DAA) and closed fermented seeds (SFD) which could provide a better seed quality.
 Conclusion: Agronomic performances (viability and vigor) are influenced by both harvest date and fermentation method. Late harvesting of the fruit (40 DAA) and fermentation in a very confined deep soil condition (SFD) ensures the production of high germination quality seeds.

Conventional and Ultra-fast Analysis Exposing the Harvest Date Impact on Lebanese Olive Oil: The Soury Variety

The impact of harvest period on the quality parameters, polyphenols, fatty acids, sterols, and volatile compounds of Lebanese olive oil from the Soury variety was investigated in this study. Two groups of olive oil were compared, each with a specific harvest date. HD1 was harvested in October, whereas HD2 was picked in November. The analysis of both olive oil categories showed that HD2 witnessed a significant increase in all quality parameters except K270 and a decrease in total polyphenol content from 138 mg/mL to 44 mg/mL. Oleic and linoleic acids had an inverse relation, where the former decreased and the latter increased with the harvest date’s advancement. Palmitic acid in both groups was higher than the standards set for extra virgin olive oil. The relative amount of β -Sitosterol was mainly found to decrease, while those of stigmasterol, ∆5,24 -stigmastadienol, ∆7 -stigmastenol, and ∆7 -avenasterol increased with delaying harvest time. As for the volatile compounds, principle component analysis was used on the flash GC data to differentiate HD1 from HD2. Ethanol was found mostly characterizing HD2, whereas HD1 was influenced by 1-hexanol and (E,E)-2,4-decadienal. It can be concluded that the Soury variety should be harvested early, and a delay would result in the declassification of Lebanese olive oil quality from extra virgin to virgin olive oil.

Some physical properties of lentil seeds affected by harvest time

Abstract: The physical properties and the hardness of lentil seeds, which can also be affected by harvest times, are very important variables in the designing and adjustment of machineries used during harvest, handling and other processes. The objective of this study is to determine the effects of different harvest times on some physical and mechanical properties of lentil seeds. A field experiment was conducted at six harvest times including the harvesting at physiological maturity (H1) and 5, 10, 15, 20 and 25 days after physiological maturity (H2, H3, H4, H5 and H6, respectively). The variables determined were moisture content, diameter, thickness, sphericity, seed mass, bulk density, true density, porosity and hardness of lentil seeds. It was found that seed moisture content, seed dimensions, seed mass and bulk density decreased with delayed harvest time. However, sphericity, true density, porosity and hardness of lentil seeds increased with increased harvest time.

THE YIELD AND QUALITY PROPERTIES OF CHICKPEA SEEDS (CICER ARIETINUM L.) AFFECTED BY HARVEST TIMES

Harvesting of chickpea (Cicer arietinum L.) seeds at right time of maturity is one of the important issues because pod dropping and shattering is a major problem during harvest. Also, the physical properties of chickpea seeds can be affected by harvest time. For this purpose, a field experiment was carried out to examine the effects of harvest times after physiological maturity on the seed yield per plant and the seed quality properties in chickpea production. The treatments used in the experiment consisted of five harvest times, which chickpea pods were harvested at physiological maturity (H1) and 5, 10, 15, and 20 days after physiological maturity (H2, H3, H4 and H5, respectively). The physiological maturity time (R7) was considered as the stage that leaves start to yellow and 50% of pods are yellow. Moisture content, dimension properties, hundred seed weight, true density, bulk density and porosity and seed yield per plant was determined in the study. The results showed that all measured variables were affected by harvest time. The true density and porosity increased with delayed harvest time. But, the other measured variables decreased when harvest was delayed.

Determination of ϒ-aminobutyric acid (GABA) in jujube fruit (Ziziphus jujuba Mill.)

ABSTRACTϒ-aminobutyric acid (GABA) is a ubiquitous non-proteinaceous amino acid with many health-promoting benefits. GABA in some fruits has been reported previously. However, there have been no previous reports of GABA in jujube fruit. Therefore, the purpose of this study was to investigate the content of GABA in different jujube cultivars and the effect of harvest, drying and storage on GABA of jujube fruit. In six jujube cultivars studied, Z. Jujuba cv. Junzao had the highest GABA content of 333.37 µg.g−1 DW, while Z. Jujuba cv. Dongzao had the lowest GABA content of 150.31 µg.g−1 DW. The GABA content of jujube fruit (Z. jujuba Mill.cv.Junzao) was nearly doubled by delaying harvest time probably due to cold stress, while it was significantly decreased by the treatment of drying and storage. Interestingly, these findings suggest that normal consumption amount of jujube fruit might contain sufficient GABA to produce the effects of improving sleep and lowering blood pressure.

Impact of Harvest Time and Cultivar on Conversion of Switchgrass to Bio-oils Via Fast Pyrolysis

The study of the effects of harvest time on switchgrass (Panicum virgatum L.) biomass and bioenergy production reported herein encompasses a large study evaluating the harvest of six switchgrass cultivars grown at three northern US locations over 3 years, harvested at upland peak crop (anthesis), post-frost, and post-winter. Delaying harvest of switchgrass until after frost and until after winter has resulted in decreased yields of switchgrass and reduced amounts of minerals in the biomass. This report examines how changes in biomass composition as a result of varying harvest time and other factors affect the distribution of products formed via fast pyrolysis. A subset (50) of the population (n = 864) was analyzed for fast pyrolysis and catalytic pyrolysis (zeolite catalyst) product yields using a pyrolysis-GC/MS system. The subset was used to build calibrations that were successful in predicting the pyrolysis product yield using near-infrared reflectance spectroscopy (NIRS), and partial least squares predictive models were applied to the entire sample set. The pyrolysis product yield was significantly affected by the field trial location, year of harvest, cultivar, and harvest time. Delaying harvest time of the switchgrass crop led to greater production of deoxygenated aromatics improving the efficiency of the catalytic fast pyrolysis and bio-oil quality. The changes in the pyrolysis product yield were related to biomass compositional changes, and key relationships between cell wall polymers, potassium concentration in the biomass, and pyrolysis products were identified. The findings show that the loss of minerals in the biomass as harvest time is delayed combined with the greater proportion in cellulose and lignin in the biomass has significant positive influences on conversion through fast pyrolysis.

The Effect of Soil Textures on the Flowering characteristics and Green Manure Yield of Crimson Clover (Trifolium incarnatum L.) in Upland Soil

Crimson clover, a legume crop, is a landscape crop and green manure crop that can be sowing in spring and autumn. Its red flower blooms in May, and serves various roles such as landscape composition, weeds suppressing, prevention of soil loss and nutrient on sloping land and supplying nitrogen and organic matter in soil. Thus, in order to utilize this crop in agriculture land, we evaluated the growth characteristics of crimson clover cultivated in four different soil textures; sand, sandy loam, loam, and clay loam. The nitrogen content of crimson clover was 15.8 g kg-1 and C/N ratio was 20.3. Its plant height was 42.5 cm in sandy loam and 49.5 cm in loamy, respectively, approximately 20 cm longer than the sand and clay loam. The crimson clover in sandy loam and loam bloomed about seven days earlier than those in sand and clay loam. Regarding number of flower per hill and flower length, there were no difference among the soil textures. Dry weight of crimson clover for sandy loam and loam was 2.5 Mg ha-1 and 2.3 Mg ha-1, respectively, 0.8 ~ 1.1 Mg ha-1 higher than that of sand and sandy loam. Plant height and dry weight of crimson clover increased with delaying harvest time. Nitrogen contribution in loam and clay loam was 51.3 kg ha-1 and 53.5 kg ha-1, respectively. Therefore, in terms of flowering properties and dry weight, the proper soil texture for the growth and development of crimson clover was sandy loam and loam. The Dry weight of crimson clover as affected by soil texture in upland soil.

Impact of Harvest Time and Switchgrass Cultivar on Sugar Release Through Enzymatic Hydrolysis

Switchgrass (Panicum virgatum L.) is a native North American prairie grass being developed for bioenergy production in the central and eastern USA. The objective of this study was to identify the impacts of harvest time and switchgrass cultivar had on sugar release variables determined through enzymatic hydrolysis. Previously, we reported that delaying harvest of switchgrass until after frost and until after winter resulted in decreased yields of switchgrass but it reduced the amount of ash and nutrients in the biomass. The current study used near-infrared reflectance spectroscopy (NIRS) to broaden an existing set of calibration equations designed to predict composition and sugar release variables of switchgrass. These updated calibrations were then applied to the full set of samples from a multi-year and multi-location switchgrass harvest-management study. Composition and processor sugar yields were significantly affected by location, year, cultivar, and harvest time, of which the time of harvest was the most important. Delaying the time of harvest until after frost or post-winter increased the concentration of structural carbohydrates from 500 to over 570 g kg−1 in the biomass and lignin content from 160 to over 200 g kg−1. Conversely, delaying harvest time lowered the amounts of ash and soluble sugars. The later harvest times also yielded more sugars following processing with yields increasing over 20% from the first harvest. Increased sugar yields are attributable to both increased concentration of sugars in the biomass upon harvest and reduced biomass recalcitrance. Based upon processed sugar yields, it is estimated that a biorefinery producing 76 million liters of ethanol per year would require 229–373 km2 of land cultivated with switchgrass.

NPK Levels and Application Methods on Productivity of Amorphophallus muelleri Blume in Intercropping System

Underground corm of Amorphophallus muelleri Blume contained glucomannan, a raw material widely used in beverage, food and medicinal industries. In Indonesia, A. muelleri is grown under intercropping system, however, average corm production was considered low. The low productivity could be related to the low input of chemical fertilizers. Therefore, the effects of NPK fertilizers and methods of application on A. muelleri productivity were evaluated in the present study for intercropping system. Two experiments were conducted at Leuwikopo Experimental Farm, Bogor, Indonesia from 2010-2012 under canopy of coffee trees. First experiment was conducted using four levels of N, P, and K applications, i.e., N:P2O5:K2O at the rate 0:0:0, 100:60:80, 125:60:100 and 150:60:120 kg ha-1. In second experiment, N:P2O5:K2O fertilizers at the rate of 100:60:80 were applied by conventional (solid) and liquefied. Results of first experiment showed that application of N, P and K at rate of 100 kg, 60 kg, and 80 kg ha-1 produced fresh corm weight 636.3±91.7 g per plant or increased by 63% higher than control. However, higher rate of NPK application did not increase corm yield, possibly due to the occurrence of leaf discoloration. Higher rates of NPK also delayed harvest time 1 to 2 weeks compared with control and caused wide variation of corm size. Thus, excess application of NPK should be avoided for high productivity of A. muelleri. Second experiment showed that there was no significant different among methods of application on fresh corm weight, i.e., 413 g and 396 g from conventional and liquefied applications, respectively. These experiments conclude that application of NPK is important to enhance A. muelleri production in intercropping system.

NPK Levels and Application Methods on Productivity of Amorphophallus muelleri Blume in Intercropping System

Underground corm of Amorphophallus muelleri Blume contained glucomannan, a raw material widely used in beverage, food and medicinal industries. In Indonesia, A. muelleri is grown under intercropping system, however, average corm production was considered low. The low productivity could be related to the low input of chemical fertilizers. Therefore, the effects of NPK fertilizers and methods of application on A. muelleri productivity were evaluated in the present study for intercropping system. Two experiments were conducted at Leuwikopo Experimental Farm, Bogor, Indonesia from 2010-2012 under canopy of coffee trees. First experiment was conducted using four levels of N, P, and K applications, i.e., N:P2O5:K2O at the rate 0:0:0, 100:60:80, 125:60:100 and 150:60:120 kg ha-1. In second experiment, N:P2O5:K2O fertilizers at the rate of 100:60:80 were applied by conventional (solid) and liquefied. Results of first experiment showed that application of N, P and K at rate of 100 kg, 60 kg, and 80 kg ha-1 produced fresh corm weight 636.3±91.7 g per plant or increased by 63% higher than control. However, higher rate of NPK application did not increase corm yield, possibly due to the occurrence of leaf discoloration. Higher rates of NPK also delayed harvest time 1 to 2 weeks compared with control and caused wide variation of corm size. Thus, excess application of NPK should be avoided for high productivity of A. muelleri. Second experiment showed that there was no significant different among methods of application on fresh corm weight, i.e., 413 g and 396 g from conventional and liquefied applications, respectively. These experiments conclude that application of NPK is important to enhance A. muelleri production in intercropping system.

Evolution and Distribution of Hydrolytic Enzyme Activities during Preharvest Sprouting of Wheat (Triticum aestivum) in the Field.

To date, research on preharvest sprouted (PHS) wheat has mostly been conducted on kernels germinated under laboratory conditions, which differ widely from conditions in the field. To obtain detailed knowledge of the evolution of hydrolytic enzyme activities in PHS wheat (Triticum aestivum), a broad collection of samples from three varieties was obtained by harvesting before, at, and after maturity. Delaying harvest time coupled with periods of heavy rainfall caused sprouting in the kernels, observed as a drop in Falling Number and an increase in α-amylase activity. The appearance of α- and β-amylase, peptidase, and endoxylanase activity during field sprouting was independent from each other. Consequently, Falling Number could not be used to predict activity of other hydrolytic enzymes. When differentiating endogenous from kernel-associated microbial enzymes, results showed that α- and β-amylase and peptidase activity of PHS kernels were predominantly of endogenous origin, whereas endoxylanase activity was largely from microbial origin.

Evaluation of fruit quality and antioxidant activity of kiwifruit during ripening and after storage

BACKGROUND: In the Northern hemisphere kiwifruit harvest time is conditioned by low temperatures occurring during the harvesting season while in Southern Italy minimum temperatures in autumn are high enough to support fruit growth and ripening. To evaluate the influence of delayed harvest time on kiwifruit quality attributes. METHODS: The experiment was carried out in a commercial kiwifruit, ‘Hayward’, orchard located in Southern Italy. In this area, the conventional harvest time occurs 160 days after full bloom (DAFB), during the first decade of November. Fruits were collected from 130 DAFB to 192 DAFB. Fresh fruit and dry weight, flesh color, firmness, total soluble solids content (TSS), titratable acidity (TA), ascorbic acid (AA), total polyphenols content (TPH) and antioxidant capacity (TAC) were determined. After 120 days of storage, fruit harvested 178 DAFB, had higher fresh and dry weight, flesh firmness, TSS, TA and lower water loss than fruit harvested at 160 DAFB, with no significant differences in AA, TPH and TAC. TAC was correlated more to TPH than to AA. Early (130–158 DAFB) harvests, resulted in poor fruit quality and scarce post harvest maintenance. Delaying fruit harvest time, in mild winter areas such as Southern Italy, resulted in an improved fruit

Comparative behavior of wheat and barley associated with field release and grain weight determination

Double-cropping using the wheat–soybean sequence is a common practice in Argentina to promote the intensification of crops within rotations. However, the late release of the fields by a delayed harvest time in wheat determines soybean yield penalizations. In this context, barley could represent a better option than wheat preceding soybean in the crop rotation since there is some evidence that finishes its cycle earlier than wheat. However, it is not clear which period of barley shortens crop cycle allowing an earlier field release than wheat. The objectives of this study were to compare wheat and barley in terms of (i) field release and (ii) grain weight determination through the analysis of their physiological mechanisms. Field experiments during two consecutive growing seasons testing five different environments (three sowing dates in 2007 and two in 2008) were carried out to analyze the duration of different ontogenic periods and the attributes (dry matter and water dynamics) determining grain weight during the grain-filling period in wheat and barley. Early flowering time was the main cause of the early field release by barley as the grain filling and drying period were similar in both species. A strong relationship was found between dry matter and water dynamics in both species. Barley reached a higher maximum water content than wheat and also achieved physiological maturity with higher moisture concentration than wheat (48% and 39%, respectively). Barley showed a slight increase in grain weight, respect to wheat, due to a source:sink ratio enhancement (4% and 9% for wheat and barley, respectively). These data show an opposite response to that of Mediterranean, Australian and UK environments, where barley was under stronger sink limitation than wheat during the grain-filling period.

간척지에서 수확한 옥수수 AG-BAG 사일리지의 품질에 관한 연구

본 연구는 논에서 재배된 옥수수를 이용하여 AG-BAG 사일리지의 품질에 미치는 영향을 구명하기 위하여 충남 석문 간척지에서 수행되었다. 옥수수 AG-BAG 사일리지의 수분함량은 68~79% 범위를 유지하였고, pH는 3.49-3.65을 유지하였으며 수확기간에 따른 차이는 크지 않았다. 수확기가 늦어짐에 따라 AG-BAG 사일리지의 조단백질 함량은 감소하는 경향을 보였으나 섬유소인 NDF 및 ADF 함량은 증가하였다. 또한 수확기가 늦어짐에 따라 젖산 함량은 증가되었으나(P<0.05) 초산 함량은 감소되었다. 따라서 본 연구에서는 대단위 간척지 논에서 재배된 옥수수 사일리지 제조에 AG-BAG의 이용은 사일리지 발효가 양호하여 품질을 향상시켰을 뿐 만 아니라 옥수수 사일리지 제조에 경제적이며 효율적인 방법의 하나가 될 수 있다는 것을 보여주었다. This study was carried out to examine the nutritive values and quality of agricultural bag (AG-BAG) silage manufactured with corn grown in reclaimed paddy field of Sukmoon at Dangjin Province in Korea. The cultivars of silage corn used in this experiment 1 were both Kwangpyungok and P32B33. The fertilizer were applied with the amounts of customary applications (200 kg N/ha, 150 kg <TEX>$P_2O_5$</TEX>/ha and 150 kg <TEX>$K_2O$</TEX>/ha). The content of moisture in corn AG-BAG silage ranged from 68 to 79%. The pH in corn AG-BAG silage stages ranged from 3.49 to 3.65 and was not influenced by the harvest time. The contents of crude protein (CP) in corn AG-BAG silage decreased with delayed harvest time. However, the contents of ADF (acid detergent fiber) and NDF (neutral detergent fiber) increased. The content of lactic acid increased with delayed harvest time, but the content of acetic acid decreased. Therefore, we suggest that the system of AG-BAG silage can improve the quality of corn silage and be one of the economical and effective methods to manufacture corn silage.

Cuticular wax load and surface wettability of leaves and fruits collected from sweet cherry (Prunus avium) trees grown under field conditions or inside a polytunnel

In this work, the effect of microclimate at the tree level inside a polytunnel and in an uncovered orchard of Prunus avium was studied through the observation of leaf and fruit micromorphology and the accumulation of cuticular waxes. Records of environmental parameters showed a significantly higher daytime temperature in the polytunnel (on an average 4°C), whereas the night temperature did not differ between treatments. Furthermore, photosynthetic active radiation and UV-B radiation inside the polytunnel were 43 and 97% lower, respectively, than the radiation measured outside. Leaves grown in the polytunnel had lower contact angles and higher load of cuticular wax per unit area, irrespective of cultivar. The impact of the microclimate was observed at the first sampling and did not increase with exposure time of leaves. Fruits of the cultivars ‘Souvenir’ and ‘Prime Giant’ grown outside had significantly less cuticular wax despite their delayed harvest time of 11 and 5 days, respectively. The relationship of higher cuticular wax load and lower contact angles of protected leaves might have practical importance for plant protection activities and the retention and uptake of leaf-applied agrochemicals.

Influence of harvest date and geographical location on kernel symptoms, fungal infestation and embryo viability of malting barley

This study focused on the influence of harvest timing and geographical location on spring malting barley (potential malting variety) in terms of fungal infestation and seedling viability in symptomatic and asymptomatic kernels. The study was conducted over two consecutive crop years (2003–2004) at four locations in Slovakia. The following categories of the barley kernels were used for the assessment: kernels with black point symptoms (BPK), kernels with black cover on their surface (BCK), pink-colored kernels (PCK) and asymptomatic kernels (AK). The occurrence of various fungi was detected in all kernel categories ranging from 60 to 100%. The most frequent fungal contaminants were members of the genus Alternaria, recovered from BPK in the range of 52.6–69.85%, BCK (62.36–73.28%) and AK (55.35–69.58%). The prevalence of Alternaria spp. was recorded for each harvest time. Other dematiaceous fungi, Epicoccum nigrum and Cochliobolus sativus were found with medium frequency in the same three categories. However, C. sativus was recovered with a higher frequency in BPK (2.6–25.3%). In PCK, the most commonly recovered fungi were species of Fusarium with F. avenaceum (59.2–93.2%) as the most prevalent. The infestation of kernels by fungi from other genera showed only low frequency within all the kernel categories investigated. There was no significant influence of the year and location on the proportion of the symptomatic kernel categories. Kernel germination was inhibited to a greater degree in the wetter and colder year. The strongest inhibition of germination ranging from 2.35 to 22.45% was recorded in PCK in all locations and both years. Germination declined from PCK to BCK (43.2–90.32%), and BPK (45.6–91.61%), while it was highest in AK at all harvest times (63–93.6%). This study found that the black covering symptoms (BCK) caused greater damage to viability of the kernels than black point symptoms (BPK). The delayed harvest time resulted not only in increasing numbers of discolored kernels and undesirable symptomatic kernel fractions but also in lower germination of the kernels tested.

An Evaluation of Blueberry Cultivars Grown in Plastic Tunnels in Douglas County, Oregon

Growing fruits and vegetables in plastic tunnels is known to accelerate maturity and protect quality. There are several studies on highbush blueberry (Vaccinium corymbosum) that demonstrate the ability of row covers to advance or delay crop maturity depending on how they are manipulated. Accelerating or delaying harvest time can prove to be very lucrative for producers. However, before producers start putting plastic tunnels over their crops it is important to know how blueberry cultivars will behave when grown under plastic. Six cultivars of southern highbush blueberry and eight cultivars of northern highbush blueberry were grown in a high hoop plastic tunnel for two seasons. Blueberry plants were grown under plastic from February 1 until their harvest was completed each year. After harvest, the plastic covering over the hoops was removed to help the blueberry plants develop fruit buds and meet winter chill requirements. On February 1 the plastic covering was returned to the high hoop tunnel after chilling requirements were met. As expected, fruit maturity dates were 1-3 weeks earlier for all the highbush blueberries grown inside the tunnel versus the same cultivars grown outside. The difference in maturity dates between cultivars grown under plastic and outside did change from one year to the next because of variation in the weather. Despite potential for poor pollination of blueberries in plastic tunnels, yields were significantly enhanced for four cultivars when grown under plastic tunnels. ‘Toro’, ‘Nui’, ‘Legacy’, and ‘Misty’ showed yield gains ranging from 1 to 4 times when grown under a plastic tunnel. Seed numbers per fruit were not significantly impacted by growing plants inside our tunnel.

The effect of delayed harvest on moisture content, insect damage, moulds and aflatoxin contamination of maize in Mayuge district of Uganda

AbstractField drying is a traditional practice carried out by farmers in Uganda and it is one of those practices reported to affect the postharvest quality of maize. A study was therefore conducted to establish the effects of delayed harvest on moisture content, insect damage, moulds and aflatoxin contamination of maize in Mayuge district. Sixteen farmers were selected from Bayitambogwe sub‐county, eight from each of the villages of Bugodi and Musita. Maize was sampled from each farmer's field in 2003B and 2004A seasons at harvest stages of physiological maturity and after delayed harvest for 1, 2, 3 and 4 weeks. Each sample was analysed for mould incidence, moisture content, insect damage and aflatoxin contamination. In each season, mould incidence, insect damage and aflatoxin levels significantly (P &lt; 0.05) increased with delayed time of harvest. Moisture content reduced with delayed harvest time but the maize did not dry to the required safe storage moisture content of ⩽15%. Seasonal effects were only significant for moisture content: the 2003B crop had consistently lower moisture content than 2004A crop. These results indicate that, for improved harvest quality of maize, farmers should harvest no later than 3 weeks after maize has attained physiological maturity. Copyright © 2005 Society of Chemical Industry