Harvest Duration Research Articles

TOWARD A BETTER INTERPRETATION AND USE OF THERMAL TIME MODELS

Thermal time models express the temperature dependence of plant or organ development and are mostly used to predict phenological events over time. The most general thermal time model is the accumulation of daily mean temperatures above a threshold temperature [theta] during a development phase. The predictive quality of the model depends on the value of the parameter [theta]. However, the physiological and mathematical bases for [theta] estimation are sometimes forgotten, leading to questionable interpretation. Threshold temperatures [theta] have been estimated for the flowering to harvest phase of two tropical fruit species. For strawberry guava, a large and variable set of data, collected in orchards at different elevations, was available, and [theta] was estimated by five different statistical methods. For mango, few data were available and [theta] was estimated as a parameter of the fruit growth curve. Estimated [theta] values were - 3.9°C for strawberry guava and 20.0°C for mango. For strawberry guava, discrepancies between the model and data were significantly correlated with orchard elevation, fruit set ratio and flowering to harvest duration, but not with the mean temperature of the phase. These results are discussed with a special emphasis on three points which could improve thermal time models and their use: the significance of the threshold temperature [theta], the domain of validity of the model, and the influence of factors other than temperature on plant development. (Resume d'auteur)

The culture duration affects the immunomodulatory and anticancer effect of polysaccharopeptide derived from Coriolus versicolor

Polysaccharopeptide (PSP) derives from the medicinal mushroom Coriolus versicolor is considered a biological response modifier with potential pharmaceutical applications. Significant literatures support the immune and anticancer functions of PSP; however, standardization is of big concern because variable biotechnological factors can affect both the chemical and biological properties of PSP. In this study, the extracts of PSP obtained at different days from the Coriolus versicolor culture were tested in vitro for their immune function on human normal peripheral blood mononuclear cells (PBMC) and cytotoxicity on the human leukemia Molt 4 cells. Over the 10-days culture period, both biomass and peptide/polysaccharide content were increased with time. The increase in proliferation index of PBMC and their production of interleukin 1 beta (IL-1β), tumor necrosis factor alpha (TNF-α) and gamma interferon (IFN-γ) in the presence of PHA strengthens the correlation between culture duration and biological potency of PSP. The growth inhibition of the Molt 4 cells by PSP also depended on its maturity. Flow cytometry analysis on cell cycle and cell death (apoptosis) of Molt 4 cells indicated that the anticancer mechanism of PSP is related to its ability to induce S-phase cell arrest and apoptosis, respectively. Together, these results suggest that monitor the harvest duration is critical for the quality control of polysaccharopeptide in the biotechnological industry.

Production and quality of greenhouse roses in recirculating nutrient systems

Greenhouse-grown rose plants were grown in either a non-recirculating (open) nutrient system, or a recirculating (closed) nutrient system with or without one of five amendments. Recirculation had no effect on harvest parameters during the first 8 weeks of the harvest period, but had a negative impact on stem length during the second 8 weeks, and on stem number and length when averaged over the entire harvest duration. Differences were not likely caused by changes in electrical conductivity or macro-nutrient concentrations of the nutrient solutions. Amendments to the recirculated solutions consisted of increased concentrations of Ca, B or Si, reduced pH, or use of an adsorbent resin to remove specific organic molecules. All amendments mitigated the negative effects of recirculation on at least two harvest parameters, but only during the second-half of the harvest period. With the exception of the intentional changes, mineral status of the nutrient solutions were similar in all recirculated treatments. Leaf chlorosis was observed in all recirculation treatments. It is likely that the reduction in rose quantity and quality in recirculation is caused by a combination of factors, some of which were ameliorated through the addition of specific amendments to the solution.

Variations in the yield and fruit characters of some guava (Psidium guajava L) accessions in Ibadan, Southwestern Nigeria

A germplasm collection block of guava containing nine accessions was established in Ibadan to assess variations in metrical, visual and other fruit yield characters for the purpose of selection for good quality fruit. The results showed that four years after planting only accessions TB85/2885 and TB85/2887 had high survival percentages of 90% and 86% respectively. Most of the accessions produced fruits two years after planting. The accessions were significantly different with regards to fruit yield and metrical characters. Based on harvest duration, two groups of guava were identified – early fruiting (July-September) and late fruiting (August-October). The harvest duration varied among accessions from four weeks to nine weeks. All accessions were inferior to the improved varieties in terms of small fruit size and low fruit/seed weight proportion. Nevertheless, TB85/2885 may be selected among the accessions for its good survival on poor soil, big fruits, high fruit/seed weight proportion, long fruiting duration as well as availability of its fruits off-season. Key Words: Accessions; guava; harvest duration;, metrical characters; percentage survival Moor J. Agric. Res. Vol.4(1) 2003: 71-77

Probabilistic Model of Fruit Removal during Vibratory Morello Harvesting

The quantity of the fruit removed under specified harvest conditions and duration of the vibratory impact on a fruit-bearing tree are analysed in the present study, considering the harvest duration as a random variable. Defined are basic probabilistic-statistical characteristics of the removal of a fruit set belonging to a fruit-bearing tree subjected to vibrations, thus establishing a probabilistic model describing mathematically the vibratory fruit removal under different specified harvest conditions. By means of both conducted and previously published morello harvested experiments, it is established that under different harvest conditions and characteristics of the vibratory impact on a fruit-bearing tree, the relative quantity of the non-detached fruit from the tree and the probability for non-sufficient harvest duration are coincident and both decrease exponentially when the vibratory impact duration for the tree increases. Tests of the concordance between the experimental data and the statistical hypothesis for exponential probability distribution of the harvest duration show that at the 0·01 level of significance, the experimental data does not contradict the raised hypothesis. The value of the correlation coefficient between the experimental and predicted results is ≈0·99.

Correlation and path coefficient analysis of yield attributes in ber (Zizyphus spp.).

Correlation and path coefficient were studied for thirteen yield attributing characters in eleven genotypes of ber. Fruit set, fruit length, fruit breadth, fruit weight, stone diameter, pulp weight, specific gravity and harvest duration had significant positive correlation with fruit yield. At genotypic level, fruit length showed the highest direct positive effect on fruit yield followed by fruit weight and fruit breadth.

Application of a population dynamics model to the Mediterranean mussel, Mytilus galloprovincialis, reared in Thau Lagoon (France)

A population dynamics model developed for oysters cultured in Thau Lagoon was applied to the mussel, Mytilus galloprovincialis, that are raised in the same area. This model is based on a continuous equation of mussel abundance as a function of mortality rate, individual growth rate and inter-individual growth variability. The growth model was calibrated with growth, water temperature ( T, °C) and particulate organic matter concentration (POM, mg l −1) data that were measured in the lagoon between March 2000 and October 2001. The daily growth rate ( G in g day −1) was modelled as a function of POM, T and total individual mass, w ( G= a POM b T c w d ). A diffusion coefficient (value of 0.01) simulated the inter-individual growth variability in the general population dynamics equation. The population dynamics model used seeding and harvesting timetables (collected during interviews of mussel farmers in Spring 2001) for estimating inputs and outputs (i.e. mass of individuals at seeding and harvest, rearing density) for the basin; thus the cultivation strategies of mussel farmers were explicitly included in the model formulation. Simulations of long-term variations in the standing stock and the marketable production of mussels showed that predicted variations in the standing stock at equilibrium were between 3600 and 4300 t (equilibrium conditions reached in 3 years) and the annual production of mussels was estimated at 5400 t. The model results are particularly sensitive to parameters governing harvest. The results suggest that summertime is the best period for seeding to shorten the harvest duration.

Avaliação de técnica de tomaticultura em gramado (TEG) na amazônia oriental

No Brasil, o tomateiro é cultivado principalmente em época de baixa precipitação e temperaturas amenas como as regiões Sudeste, Nordeste e Centro Oeste. Na Amazônia Oriental, uma região tropical úmida de baixa altitude, com temperatura elevada, a cultura do tomateiro enfrenta muitas dificuldades. A baixa produtividade e a mortalidade das plantas têm reduzido o número de produtores desta hortaliça, com a produção local de tomate inferior a 0,1% do volume comercializado anualmente. A técnica de Tomaticultura Em Gramado (TEG) foi concebida em 1997 e aperfeiçoada em 1998, para solucionar os problemas da tomaticultura sob clima quente e chuvoso da Amazônia, usando dois principais mecanismos: 1. Campo gramado para controlar a proliferação de doenças, pragas, plantas invasoras, erosão e lixiviação de nutrientes. 2. Queima de descarte de madeira na área de cultivo para eliminar a grama e reduzir a acidez e pobreza do solo. O presente trabalho apresenta resultados preliminares de tomaticultura sob essa nova técnica, com avaliação de produtividade, ciclo da planta e peso médio do fruto. A nova técnica de cultivo permitiu a produtividade de 5,6 ± 0,2 kg por planta, sendo o período de colheita de 60 a 80 dias. A TEG demonstrou ser uma alternativa promissora para o sistema de produção de tomate na região quente e chuvosa, usando a gramínea como protetora e limpadora do solo.

Production potential and economics of different sowing dates for babycorn (Zea mays) production under mid-hill conditions of North-western Himalayas . .

A field experiment was conducted during 1998, 1999 and 2000 at Almora, to find out production potential and economics of different sowing dates for babycorn (Zea mays L.) production. The highest babycorn yield (1,688 kg/ ha) net return (Rs 35, 249tha) and benefit : cost ratio ( 2.41) were recorded under 2 May sowing, followed by 17 April sowing, with corresponding values 1, 679 kglha, Rs 34,753tha and 2.39 respectively. Crop sown in August was not found remunerative. The highest green fodder yield (377 q/ha) was recorded on 1 June sowing which, however, was at par with sowing done during mid-April to May, but significantly rnore than all other sowing dates. Maximum days to babycorn initiation (63 days) and harvest duration (1 3 days) were recorded with 2 April sowing which decreased significantly in subsequent sowing dates. Highest babycorntplant (2.1) was recorded on 17 April and 2 May sowings which, however, was at par with 2 April sowing but significantly more than all other sowing dates.

488 The Effect of Population Densities, Vine Training Methods, and Harvest Duration on Shoot Yield of Fluted Pumpkin (Telfairia occidentalis)

Nursery-sown seedlings of Telfairia occidentalis were transplanted to the field plots of the National Horticultural Research Inst. in May 1998 and 1999. The treatment involved sowing using three population densities of 75,000; 45,000, and 30,000 plants/ha, which translates to 50 × 50-cm; 100 × 50-cm and 100 × 100-cm spacing. The second experiment involved sowing at 1 × 1-m spacing and one, two, four, zero, eight, and 12 harvests with staking vs. non-staking of vine methods. The studies were of a completely randomized block design using four replications. The results showed that most of the vegetation plant characters measured in the study on one hand were favored by 75,000 plants/ha, while, on the other hand, the highest fruit production occurred in 45,000 plants/ha. Harvesting eight to 12 times gave similar, but significantly higher,vegetative yield than the other lower frequencies. Nevertheless, fruit production in number and weight was superior in plants given the minimum (one or two) pruning. There were no significant differences in the measured plant characters of plants that were staked compared to the non-staked plants. However, fruit yield was better in staked than non-staked plants.

Effects of plant density and mulching on the performance of late-season tomato (Lycopersicon esculentum) in southern Nigeria

The growth and yield of late-season tomato was studied at Akure, Nigeria, from 1995 to 1998. In each year, treatments were 0 (bare ground) or 12 kg/ha grass mulch applied to tomatoes at densities of 1·9, 2·8, 3·7 and 5·6 plants/m2 in a factorial combination. Increase in plant density and mulching reduced soil temperature at 5 cm depth while only the latter enhanced soil moisture at 10 cm depth throughout tomato growth. The improved soil hydrothermal regime resulted in earlier onset of flowering, 50% flowering date and date of first harvest respectively and shorter fruit harvest duration in tomato grown on either bare ground or at increased plant density.Although increased plant density reduced shoot dry weight per plant at final harvest, both root length per plant and root dry weight per plant were enhanced. Fruit yield/ha increased as plant density increased although yield of the individual plants and their components were significantly reduced. Because of compensation at higher plant population densities, it is economical to grow late-season tomato at 5·6 plants/m2. Mulching enhanced growth and yield of tomato compared to bare ground and the result emphasizes the need for early and rapid growth of late-season tomato before the onset of terminal drought.

Genetic association between DNA fingerprint fragments and loci controlling agriculturally important traits in avocado (Persea americana Mill.)

Associations between DNA fingerprint fragments and 16 avocado quantitative trait loci were tested for in two avocado tamilies by one way analysis of variance and multiple regression analysis. Based on these two analyses the fragments P4, P8, E2 and E5 in ‘Pinkerton’ × ‘Ettinger’ progeny were found to be associated with harvest duration, skin color, skin thickness and skin surface, respectively. The fragments P1, P8, B1 and B4 in the ‘Pinkerton’ × ‘Bacon’ progeny (half sibs of the original population) were found to be associated with fruit weight, skin color, seed size and peeling, respectively. Based on the original ‘Pinkerton’ progeny as well as on the half sibs progeny, the fragment P8 was found to be associated with black-purple fruit skin color.

Effect of harvest date on the shelf life of asparagus

Abstract Commercial asparagus production occurs over an extended period in spring from carbohydrate reserves built up during the previous summer and stored in the roots. The effect of harvest duration on spear yield and quality, and on the depletion of storage root carbohydrates has been widely studied. However, little work has been reported on the effect of harvest period on the storage life and biochemistry of asparagus spears. Therefore, asparagus spears (Asparagus officinalis L. cv. Limbras 10) were harvested over the commercial harvesting season in 2 years and held at 20°C to assess shelf life and to monitor postharvest biochemistry. Shelf life declined almost linearly in both years from c. 6 days for early‐season spears to c. 3 days for late‐season spears. On the evidence of rates of protein and carbohydrate loss, and ammonia accumulation in the spear tips, the decline in shelf life was not associated with accelerated biochemical changes. Spear fresh weight at harvest (and therefore spear thickness)...

Genetic Variance Components and Heritabilities of Several Avocado Traits

Genetic variance components for avocado (Persea americana Mill.) traits were estimated to improve avocado breeding efficiency. The additive and nonadditive genetic variance components were calculated from the variances between and within crosses. In all nine traits examined, i.e.-anise scent, fruit density, flowering intensity, fruit weight, harvest duration, inflorescence length, seed size, softening time, and tree size-a significant nonadditive genetic variance was detected. Additive genetic variance in all traits was lower and nonsignificant. The existence of major nonadditive variance was indicated also by narrow-sense and broad-sense heritability values estimated for each trait. Therefore, parental selection should not be based solely on cultivar performance. Crosses between parents of medium and perhaps even low performance should also be included in the breeding program.

Effects of Artificial Defoliation on the Growth and Yield of Okra (Abelmoschus esculentus)

SUMMARYArtificial defoliation of okra 4, 6 and 8 weeks after sowing generally delayed flowering, decreased plant height and stem girth at flowering and reduced the harvest duration. Pod length, pod diameter, mean pod weight and number of pods plant−1 were also decreased by defoliation but pod yield ha−1 was not.The removal of leaves from the upper half of the stem only had a similar effect to complete defoliation whereas the removal of leaves from the lower half only had no significant effect, indicating that the leaves on the upper stem contributed more to growth and yield than those lower down. Significant time × degree of defoliation interactions occurred for most growth and yield parameters.

Effects of sowing date on the growth, yield and quality of okra (Abelmoschus esculentus (L.) Moench.) in southern Nigeria

SUMMARYTwo varieties of okra were sown at approximately 14-day intervals from 1 April to 1 June for 2 years during the main rainy season in Nigeria. Low soil temperature and moisture, which resulted from a combined effect of high solar radiation, high atmospheric temperature and low rainfall, led to poor seedling emergence at the early sowing dates.The growth of the fewer plants of the early sowing dates were more vigorous than those of later sowing dates and they attained 50% flowering earlier and had a longer harvest duration. This resulted in increases in number of pods per plant, pod length, pod diameter, pod volume, pod weight and pod yield per ha, indicating compensatory growth by the fewer plants in the early plantings. The relatively lower values obtained for these variables with the late sowing dates were also attributed to possible poor soil aeration arising from the increased rainfall during their growth period.Sowing dates did not generally affect the percentage moisture, oil and protein in the pods. The effects of varieties on the variables measured were more uniform than those of sowing dates and mostly not significant.

Effect of Harvest Duration on Yield and on Depletion of Storage Carbohydrates in Asparagus Roots1

Abstract Harvesting a young planting of asparagus (Asparagus officinalis L.) for 4 or 6 weeks the second year after transplanting 1-year-old crowns, followed by harvesting for 8 or 10 weeks the third year, reduced yields significantly the fourth year. Carbohydrate levels in asparagus storage roots decreased during harvest and continued to decrease after harvest during fern production. Carbohydrate levels increased in storage roots after stalks had matured, and were restored to preharvest levels by mid- to late summer. All treatments possessed comparable levels of storage carbohydrates by the end of the season. Asparagus storage carbohydrates were identified as fructose-oligosaccharides, which varied considerably in size, mobility, and percent fructose and glucose. The largest oligosaccharides were composed of ∼ 90% fructose, ∼ 10% glucose; molecular weights did not exceed 4,000.