Stochastic dynamic simulation of fruit abortion: a case study of sweet pepper

Abortion of reproductive organs diminishes yields in many crops. In indeterminate greenhouse crops, alternating periods of fruit abortion and fruit set exist, resulting in fluctuations in fruit yield. Factors affecting the level of abortion are e.g., the supply and demand for assimilates (source and sink strength, respectively), temperature and cultivar. However, simulation of fruit abortion is still a weak part of crop simulation models. Variation in fruit abortion exists between plants, which results in differences in the timing and the number of set fruits. Therefore, simulating fruit abortion with variation could give more realistic simulation results. The probability of a fruit to abort should be related to factors like source strength and sink strength. The more favourable the circumstances are for fruit abortion, e.g., low source strength or high sink strength, the more likely it is that the fruit aborts. Survival analysis estimates parameters quantifying the influence of explanatory variables on the abortion rate. Time-varying explanatory variables can be used in the analysis. In a case study, we used survival analysis to analyse a data set with observations on flowering, fruit abortion and fruit harvest for sweet pepper. Source and sink strength were used as explanatory variables. The resulting equation determining the probability of abortion per day was implemented in a simple simulation model to simulate fruit set. The model output, as an average of 100 plants, showed similar timing in the fluctuations in fruit set as the observations, although the amplitude of the fluctuations was in some cases underestimated. The percentage fruit set was simulated correctl

Molecular regulation of seed and fruit set

Seed and fruit set are established during and soon after fertilization and determine seed and fruit number, their final size and, hence, yield potential. These processes are highly sensitive to biotic and abiotic stresses, which often lead to seed and fruit abortion. Here, we review the regulation of assimilate partitioning, including the potential roles of recently identified sucrose efflux transporters in seed and fruit set and examine the similarities of sucrose import and hydrolysis for both pollen and ovary sinks, and similar causes of abortion. We also discuss the molecular origins of parthenocarpy and the central roles of auxins and gibberellins in fruit set. The recently completed strawberry (Fragaria vesca) and tomato (Solanum lycopersicum) genomes have added to the existing crop databases, and new models are starting to be used in fruit and seed set studies

Effects of therapeutants and temperature on pollen germination, pollen tube growth and fruit set in fruit crops : a thesis presented in partial fulfilment of the requirements for the degree of Master of Horticultural Science at Massey University

This study involved assessments of therapeutant effects on pollination and fruit set; of temperature effects on pollen germination and pollen tube growth in apples, peaches and kiwifruits; of flowerage effects on pollen germination and pollen tube growth in kiwifruit styles; and of hand pollination effects on fruit set, fruit weight and seed numbers per fruit in kiwifruit vines. From the point of view of their in vitro effects on pollen germination therapeutants can be listed in order of decreasing inhibitory effect as follows: (a) for apples - mancozeb plus dinocap, triforine, dichlofluanid, bupirimate, bayleton, citowett R captan and mancozeb; (b) for peaches - triforine, vinclozoline, streptomycin plus triforine, mancozeb, captafol, iprodione, dichlofluanid, streptomycin and benomyl; and (c) for kiwifruits - dichlofluanid, captan and vinclozoline. However, it appeared that while in vitro a therapeutant was very inhibitory, the application of a spray to anthers in an intact flower did not affect the germination of pollen subsequently released by those anthers. Fungicides proven to be toxic to pollen in vitro did not necessarily produce similarly toxic effects in vivo. Reasons for such varying effects of fungicides on pollen germination and pollen tube growth in vitro and in vivo are suggested. At 24 hours after pollination the number of pollen tubes growing more than 1/2 the style length of kiwifruit (Hayward) flowers one to two days old were 38% and 27% higher than in flowers less than one day old and more than three days old respectively. In apples 5 sprays of either bayleton or captan, 3 sprays of either of the therapeutants mancozeb, mancozeb plus dinocap, and triforine and a wetting agent citowett R applied during bloom period caused no effect in fruit set in Golden Delicious trees; and 3 bupirimate sprays during bloom period had no effect on the fruit set in Splendour trees. In peaches 6 sprays of either captafol, or benomyl or iprodione, 5 sprays of either mancozeb or vinclozoline or streptomycin or triforine during bloom period caused no effect on fruit set in Golden Queen trees. Three sprays of streptomycin or dichlofluanid caused no effect but 3 sprays of triforine, triforine plus streptomycin or of ethephon caused 50%, 70% and 90% reduction in fruit set in Red Haven peach trees. In kiwifruits 3 sprays of either dichlofluanid, captan or vinclozoline reduced seed numbers per fruit by 37% but did not affect fruit set or fruit weight. Thus in vitro and in vivo studies were useful in determining therapeutant effects on pollen but did not necessarily provide information on their effects on fruit set in apple, peach and kiwifruit and on fruit weight and seed numbers per fruit in kiwifruit. The germination of both apple and peach pollen was higher at 24°C than at 16°C, 20°C, 28°C and at 32°C. After 18 hours incubation pollen tubes were longer at 28°C and at 32°C than at 16°C, 20°C and 24°C. In vivo studies with kiwifruit (Matua) pollen showed that pollen germination at 14°C, 18°C, 22°C and 26°C did not differ significantly. Temperatures both higher and lower than the temperature range 18 to 22°C were found to be inhibitory to pollen tube growth in kiwifruit (Hayward) styles. Hand pollination of flowers did not influence percentage fruit set but increased fruit weight and seed numbers per fruit in kiwifruit (Hayward) vines. Because fruit weight was positively correlated with seed number per fruit in fruits from both bee pollinated and bee plus hand pollinated flower clusters, supplementary pollination may play an important role in the production of fruit in kiwifruit orchards

Vegetative Growth, Fruit Set, Yield and Fruit Quality of "Le-Conte" Pear Grown Under Calcareous Soil Conditions as Affected by Different Levels of Nitrogen, Phosphorus and Potassium

"Le-Conte" pear fruiting trees grown in newly reclaimed soils were fertilized with different levels of nitrogen, phosphorus and potassium fertilization during three successive seasons of 2006, 2009 and 2010. However, results were calculated for the two seasons of 2009 and 2010. Tree vegetative growth (shoot length and diameter and leaf area), fruit set, yield increased significantly with increasing fertilization level. Fruit quality was increased significantly with increasing fertilization rate. The results also indicated that increasing N, P and K fertilization level lead to a gradual increment in leaf N, P and k content. Total sugars in fruits increased significantly with increasing the fertilization levels. On the other hand, starch decreased gradually with increasing the fertilization levels. The most effective level (650g. Ammonium nitrate + 325g. Potassium sulphate + 600g. Calcium superphosphate) leads to the highest vegetative growth, mineral leaf content, fruit yield and the best fruit quality as compared with other levels of fertilization. The lowest vegetative growth, yield and fruit weight and dimensions were recorded at the lowest level (250g. Ammonium nitrate + 125g. Potassium sulphate + 200g. Calcium superphosphate)

BIODIVERSITY OF SALAK PLANT (Salacca zalacca (Gaertner) Voss)

Suwaru Salak Plant ( Salacca zalacca ( Gaertner) Voss) have been in cultivation for along time, since the Dutch coloni era in Suwaru, Gondanglegi , Malang, Indonesia. They were propagated with seed (generative propagation) the segregation process make so far more diversity (hybrid lines) in populations at salak farm. There are three main cultivars (Budeng, Madu, and Gading) and 33 Suwarufruit Salak Lines ( SSL ). The purpose of this research was to find the mthod of improvement of the cultivars. Cultivars and hybrid lines (SSL) were tested at six different objectives using variance and cluster analysis. Six experiments had been carried out, i.e. : (1) phenotype potential of salak Suwaru : (2) pollen fertility; (3) type of crossing; (4) fruit set management; (5) the time management of harvesting; (6) phenotype evaluation of salak Suwaru genotypes. This mean that pollen fertility (iodine test method) was good since it exceeded 60 %. The D type male flower had least paternal effect of acid content for cv.Madu (0.08%). The B type male flower had a highest tannin content (0.33%), paternal effect (xenia) of tanin content than A type ( 0.17% ), nearly 2 x. Xenia occured whwn the male parent carried the factor or when dominance was incomplete. Fruit set management increased fruit weight, fruit diameter, fruit volume, but decreased fruit length. The time management of harvesting increased the fruit weight and changed its edibility by increasing sugar content, decrease some acid and fruit tannin. Cluster and variance analysis showed that the degree of variance among the hybrid lines of salak Suwaru fruit was high. SSL10 and SSL28 hybrid lines may therefore be recommended as new cultivars

Chemical thinning of 'Conference' pears

The increasing difference in the market value of small and larger sized ‘Conference’ pears (>65 mm) and the high labour costs for hand thinning, makes it interesting for growers to find a cheaper and reliable method for thinning pear trees. In 2007, 2008 and 2009 trials were carried out to test the thinning efficacy of several chemicals. Fruit set was only significantly reduced by a two-fold application of ammonium thiosulphate (ATS) or by a tankmix application of 6-benzyladenine (BA) and 1-naphtalene acetic acid (NAA). Unfortunately, russeting of ‘Conference’ pears was augmented by the treatments with ATS during bloom. Tankmix applications of NAA + BA, applied at an average fruit diameter of 8.8 mm, resulted in a severe overthinning of the trees in 2008. However, the same treatments applied at an average fruit diameter of 14.7 mm had much less of a thinning effect. In 2009 adequate thinning was obtained with lower concentrations of BA+NAA applied at 8-10 mm fruit diameter. Surprisingly, the reduction in fruit set by BA+NAA did not result in a proptional increase in the average fruit weight at harvest. In some treatments average fruit weight was even reduced compared to that of the hand-thinned trees, a size-reducing effect that was attributed to NAA. In conclusion, BA+NAA seems to thin ‘Conference’ pears more strongly than BA alone. However, the addition of NAA to BA has the disadvantage of a diminishing effect on the increment of fruit size, i.e. fruit size increased less than expected on basis of the reduction in crop load. Additional research will be carried out to further optimise the developmental stage, weather conditions, and concentrations at which a BA and NAA must be applied to obtain the desired level of thinning and gain in yield percentage of fruits over 65 mm in diameter

Prediction of ‘Nules Clementine’ mandarin susceptibility to rind breakdown disorder using Vis/NIR spectroscopy

The use of diffuse reflectance visible and near infrared (Vis/NIR) spectroscopy was explored as a non-destructive technique to predict ‘Nules Clementine’ mandarin fruit susceptibility to rind breakdown (RBD) disorder by detecting rind physico-chemical properties of 80 intact fruit harvested from different canopy positions. Vis/NIR spectra were obtained using a LabSpec® spectrophotometer. Reference physico-chemical data of the fruit were obtained after 8 weeks of storage at 8 °C using conventional methods and included RBD, hue angle, colour index, mass loss, rind dry matter, as well as carbohydrates (sucrose, glucose, fructose, total carbohydrates), and total phenolic acid concentrations. Principal component analysis (PCA) was applied to analyse spectral data to identify clusters in the PCA score plots and outliers. Partial least squares (PLS) regression was applied to spectral data after PCA to develop prediction models for each quality attribute. The spectra were subjected to a test set validation by dividing the data into calibration (n = 48) and test validation (n = 32) sets. An extra set of 40 fruit harvested from a different part of the orchard was used for external validation. PLS-discriminant analysis (PLS-DA) models were developed to sort fruit based on canopy position and RBD susceptibility. Fruit position within the canopy had a significant influence on rind biochemical properties. Outside fruit had higher rind carbohydrates, phenolic acids and dry matter content and lower RBD index than inside fruit. The data distribution in the PCA and PLS-DA models displayed four clusters that could easily be identified. These clusters allowed distinction between fruit from different preharvest treatments. NIR calibration and validation results demonstrated that colour index, dry matter, total carbohydrates and mass loss were predicted with significant accuracy, with residual predictive deviation (RPD) for prediction of 3.83, 3.58, 3.15 and 2.61, respectively. The good correlation between spectral information and carbohydrate content demonstrated the potential of Vis/NIR as a non-destructive tool to predict fruit susceptibility to RBD

Pollination and Fruit Set in the Yellow Passion Fruit

The development on the use of the yellow passion fruit (Passiflora edulis forma flavicarpa Degener) for beverage, ice cream, sherbet, pastries, and other confectionaries has resulted in increased plantings of this crop in Hawaii. With this expansion, various cultural problems have been brought to the attention of the Hawaii Agricultural Experiment Station by farmers growing this crop and by the processors of passion fruit juice. In the studies reported here factors which may limit fruit set, fruit production, and juice yield have been given special attention

Mechanism of Fruit Ripening - Chapter 16

The fruit ripening process has been viewed over the last decades as being successively of physiological, biochemical, and molecular nature. Fruit ripening is accompanied by a number of biochemical events, including changes in color, sugar, acidity, texture, and aroma volatiles that are crucial for the sensory quality (Fig. 16.1). At the late stages of ripening, some senescence-related physiological changes occur that lead to membrane deterioration and cell death. In that regard, fruit ripening can thus be considered as the first step of a programmed cell death process. All biochemical and physiological changes that take place during fruit ripening are driven by the coordinated expression of fruit ripening-related genes. These genes encode enzymes that participate directly in biochemical and physiological changes. They also encode regulatory proteins that participate in the signaling pathways, and in the transcriptional machinery that regulate gene expression and set in motion the ripening developmental progra

Relationships between nutrient composition of flowers and fruit quality in orange trees grown in calcareous soil

To determine if flower nutrient composition can be used to predict fruit quality, a field experiment was conducted over three seasons (1996-1999) in a commercial orange orchard (Citrus sinensis (L.) Osbeck cv. 'Valencia Late', budded on Troyer citrange rootstock) established on a calcareous soil in southern Portugal. Flowers were collected from 20 trees during full bloom in April and their nutrient composition determined, and fruits were harvested the following March and their quality evaluated. Patterns of covariation in flower nutrient concentrations and in fruit quality variables were evaluated by principal component analysis. Regression models relating fruit quality variables to flower nutrient composition were developed by stepwise selection procedures. The predictive power of the regression models was evaluated with an independent data set. Nutrient composition of flowers at full bloom could be used to predict the fruit quality variables fresh fruit mass and maturation index in the following year. Magnesium, Ca and Zn concentrations measured in flowers were related to fruit fresh mass estimations and N, P, Mg and Fe concentrations were related to fruit maturation index. We also established reference values for the nutrient composition of flowers based on measurements made in trees that produced large (> 76 mm in diameter) fruit.info:eu-repo/semantics/publishedVersio