Maximum Fruit Set Research Articles

Impact of Micronutrients on Fruit Set and Fruit Drop of Winter Season Guava ( Psidium Guajava L. ) cv. Allahabad Safeda

A field experiment was carried out at the Horticultural Research Farm of the Department of Applied Plant Science (Horticulture), Babasaheb Bhimrao Ambedkar University during the Rabi season of 2012–2013. The experiment was laid out in Randomized Block Design with 9 treatments, replicated thrice and one branch was taken as a unit. Observations were recorded on growth, physical and quality characters of guava. The maximum fruit set percent (67.43) and fruit drop percent (58.71) were recorded maximum with foliar application of zinc sulphate + borax 0.6% and zinc sulphate+copper sulphate + borax 0.5%. Therefore, zinc sulphate + borax 0.6 percent and zinc sulphate + copper sulphate + borax 0.5% may be recommended to guava growers for obtaining better yield and quality during winter season crop of guava cv. Allahabad Safeda under Lucknow conditions.

Impact of Micronutrients on Fruit Set and Fruit Drop of Winter Season Guava (Psidium guajava L.) cv. Allahabad Safeda

A field experiment was carried out at the Horticultural Research Farm of the Department of Applied Plant Science (Horticulture), Babasaheb Bhimrao Ambedkar University during the Rabi season of 2012–2013. The experiment was laid out in Randomized Block Design with 9 treatments, replicated thrice and one branch was taken as a unit. Observations were recorded on growth, physical and quality characters of guava. The maximum fruit set percent (67.43) and fruit drop percent (58.71) were recorded maximum with foliar application of zinc sulphate + borax 0.6% and zinc sulphate+copper sulphate + borax 0.5%. Therefore, zinc sulphate + borax 0.6 percent and zinc sulphate + copper sulphate + borax 0.5% may be recommended to guava growers for obtaining better yield and quality during winter season crop of guava cv. Allahabad Safeda under Lucknow conditions.

Interacting effects of pollination, water and nutrients on fruit tree performance.

Pollination is critical to fruit production, but the interactions of pollination with plant resources on a plant's reproductive and vegetative features are largely overlooked. We examined the influences of pollination, irrigation and fertilisation on the performance of almond, Prunus dulcis, in northern California. We used a full-factorial design to test for the effects of pollination limitation on fruit production and foliage variables of whole trees experiencing four resource treatments: (i) normal water and nutrients, (ii) reduced water, (iii) no nutrients, and (iv) reduced water and no nutrients. In each of these combinations, we applied three pollination treatments: hand-cross pollination, open-pollination and pollinator exclusion. Pollination strongly affected yield even under reduced water and no nutrient applications. Hand-cross pollination resulted in over 50% fruit set with small kernels, while open-pollinated flowers showed over 30% fruit set with moderate-sized kernels. Pollinator-excluded flowers had a maximum fruit set of 5%, with big and heavy kernels. Reduced water interacted with the open- and hand-cross pollination treatments, reducing yield more than in the pollinator exclusion treatment. The number of kernels negatively influenced the number of leaves, and reduced water and no nutrient applications interacted with the pollination treatments. Overall, our results indicate that the influences of pollination on fruit tree yield interact with the plant availability of nutrients and water and that excess pollination can reduce fruit quality and the production of leaves for photosynthesis. Such information is critical to understand how pollination influences fruit tree performance.

Effect of Environmental Changes on Phenology and Reproductive Biology of Sida cordifolia with Special Reference to the Temperature and Relative Humidity

Impact of environmental factors (temperature and relative humidity) on phenology and reproductive biology of a medicinal plant Sida cordifoliaL.growing at district Agra was studied. The study revealed that phenological events (leaf fall, leaf renewal, flowering and fruiting) varied considerably with the fluctuations in temperature and relative humidity. Flowering was observed throughout the yearwith maximum in the months of FebruaryApril (11.8 �38.3∫C) and August-September (24.4-33.9∫C). Floral biology studies showed that pollen viability, pollenovule ratio and fruit -set percentage was greatly reduced with rise or fall in temperature and rela tive humidity. The maximum pollen fertility (71%), fruit set (70-90%) and pollen-ovule ratio (190:1) was recorded in the month of March when temperature was ranging between 15.1-32.6∫C with 22- 76% RH. With the fall in temperature in the month of January(6.8-17.9∫C) the pollen fertility was reduced to 52%. At the end of April 32.5 -45.3∫C with 16-43% RH, the plants under observation exhibited OriginalResearch Article

Limitations to reproductive success in the dioecious tree Rhamnus davurica.

The reproductive success of a female plant in a dioecious species may be affected by pollen limitation and resource limitation. This study presents evidence that the reproductive success of the dioecious understorey tree species, Rhamnus davurica, is affected by the distance to the nearest male. The sex ratios were female-biased, although showing fluctuations in the three years of conducting the study. The mortality rate of females was higher than that of males indicating a trade-off between reproduction and survival. Altogether 49 females, designated as “focal females”, were randomly selected for monitoring their reproductive status between April and October in 2010. But successful reproduction (meaning that the flowering female trees had fruit in the fruiting season) was observed only in 28 females in 2011 and 16 females in 2012. The method of path analysis was applied to determine the effect of topography, local competition and proximity to the nearest male on the fruit set of the females. In the three years of the study, elevation, competition and female size had no significant effect on the fruit set. The distance to the nearest male, however, had a significant effect on fruit set. Number of fruits and fruit set were decreased with increasing distance to the nearest male. It was possible to estimate maximum fruit set, based on the comparatively large dataset. The number of fruits and the fruit set are exponentially related to the distance to the nearest male and the relationships are described by an exponential model. The results of this study support the importance of pollen limitation on the reproductive success in Rhamnus davurica.

Compensation of <I>Lygus hesperus</I> Induced Preflower Fruit Loss in Cotton

A 3-yr field study quantified the compensatory ability of cotton (Gossypium hirsutum L.) to preflower fruit damage by Lygus hesperus Knight in the Texas High Plains under limited irrigation. Experiments were designed to achieve varying levels of preflower fruit loss by augmenting Lygus bug populations using nymphal bugs reared in a laboratory colony. Treatments included 1) three bugs per plant (3PP), 2) one bug per plant (1PP), 3) naturally occurring background bug density or untreated control (NC), and 4) 0 bugs achieved through insecticide spray applications (SC). Lygus release treatments (3PP and 1PP) were initiated at early fruiting (squaring) and repeated weekly for a total of three consecutive weeks. Two levels of Lygus bug infestations, one insect per plant (1PP) and three insects per plant (3PP), inflicted fruit loss percentages of 24-38 during the maximum fruit set period. Observations on the number of fruit lost at the crop preharvest stage indicate that plants receiving the 3PP and 1PP treatments exhibited higher ability to restrain physiological fruit loss when compared with the two control treatments (NC and SC). Cotton plants could not fully compensate the yield loss because of fruit damage caused by Lygus bugs at the observed level of damage. The total lint yields in the 1PP and 3PP treatments were 114 and 118 kg/ha lower, respectively, compared with that in treatment SC. The reduction in yield was primarily because of the loss of first fruiting position bolls. However, lint yields from bolls other than first position of the cotton plant were similar across treatments. Fiber quality data indicated an increase in fiber length from insect release treatment plants compared with the two control treatments.

Myrmecophily on Leucas chinensis (Lamiaceae)

Ants were identified as the most common and abundant floral visitor. The observed behaviour indicated that ants may contribute to pollination on Leucas chinensis. Detailed studies were carried out on the Phenology, floral biology, pollination and breeding system of L. chinensis. The main flowering season between August-December and occasional flowering found other seasons also. The flower is typical Lamiacean bilabiate. The inflorescence is verticillaster. Inflorescence initials are generally activated in the leaf axils. Anther dehiscence mode is longitudinal. The pollen grains were spherical and tricolpate. The size of the pollen is 26.90 ± 3.0 and 85% of pollen viable at 12am. The stigma is dry type and receptive between 12am-1.00pm. The fruit is nutlet and seed ovule ratio is 4:4. In breeding experiment we found that apomixis not present in this Leucas member maximum fruit set occur in the open pollination and xenogamy (95% and 90% respectively). The flower offer nectar and pollen as rewards for floral visitors. Flowers were visited by several insects and butterflies. The potential pollinators were Apis cerana, Amegilla sp., Ceratina sp. and Componotus parius were pollinators. The pollen grains were stuck on the ant body while visiting flower we directly documented ants movement on flower.

Response of almond (Prunus dulcis) to different drip irrigation levels vis-à-vis various phenological stages on flowering and yield of almond cv. Shalimar

Experiment was conducted to assess the effect of different irrigation levels vis-à-vis various stages of flowering, fruit set and yield of almond (Prunus dulcis Mill.) plantation cv. Shalimar. The results revealed that irrigation applied at various stages of growth and development improved flowering, fruit set and yield of almond significantly. Maximum bloom intensity, fruit set and yield were recorded with highest evaporation replenishment of 100 ETc applied throughout the season during first and second year respectively. The study further confirmed that highest flowering and yield attributes of almond recorded at 100% ETc level of irrigation were found to be statistically at par with measured parameters recorded at 75% ETc level of irrigation when applied at fruit growth stage and throughout the growth stage. The results revealed clearly that flowering and early fruit growth stages are the most critical stages of irrigation in almond and that post-harvest irrigation may prove to be beneficial.

Growth, flowering fruit set and yield in some cultivars/selections of walnut (Juglans regia)

Nine cultivars of walnut (Juglans regia L.) were evaluated during 2007–08 for growth, flowering fruit set and yield characters. Comprehensive observations on growth, foliage, floral characters and yield were recorded for each cultivar/ selection and considerable variation was observed among the cultivars for these characters. Tree height, trunk girth, tree volume and shoot extension growth ranged from 24.64 to 51.10 cm, 12.31 to 37.39 cm, 11.89 to 28.05 m3 and 29.68 to 65.14 respectively. Time of male and female flowering varied from last week of March to second week of April. All the cultivars exhibited protandry. Fruit set, fruit retention and yield varied from 19.74 to 60.57%, 25.29 to 50.82% and 0.77 to 2.15 kg/tree. Cultivar Paynee was found superior to all the cultivars and recorded maximum height, girth, tree volume, fruit set, fruit retention and yield.

Role of Paclobutrazol and Ethephon in Reproductive Growth of 'Allahabad Safeda' Guava (Psidium guajava L.) Plants at Different Spacing

A study on 4-year 'Allahabad Safeda' guava plants was made to assess the influence of Paclobutrazol (PP 333), [(2RS, 3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4 triazol-1-yl) pentan-3-ol], a gibberellin-inhibitor, and Ethephon [(2-chloroethyl) phosphonic acid], a vegetative growth inhibitor and a ripening promoter, on reproductive growth of plants. Treatments in the form of foliar application at 500 and 1000 ppm were applied consecutively during March 2007 and 2008 on plants at 6m x 2m, 6m x 3m, 6m x 4m and 6m x 5m spacing. Maximum flowering and fruit set was recorded in paclobutrazol treated plants in both rainy and winter crops. Ethephon reduced flower bud density (FBD) and fruit set during both the cropping seasons. However, Ethephon treated plants exhibited slightly higher fruit retention. Ethephon advances fruit maturity by upto a week during rainy season and two weeks during winter season. Paclobutrazol treated plants exhibited significantly higher fruit number, fruit yield, yield efficiency, fruiting density compared to Ethephon treated and control plants. Reproductive growth of plants at wider spacing of 6m x 5m and 6m x 4m significantly improved compared to closer spacings of 6m x 2m and 6m x 3m during both cropping seasons. Plants at wider spacing responded better to Paclobutrazol applications with respect to flowering and fruiting.

INTEGRATED NUTRIENT MANAGEMENT IN HIGH DENSITY GUAVA ORCHARDS

Guava exceeds the majority of tropical and sub-tropical fruit tree in adoptability, productivity and tolerance to mild cold and night frosts, besides soil pH (4.5-8.2). Owing to high nutraceutical values of guava, there has been a growing consumer preference, resulting in expansion of area across the country. Among the various factors, which affect the production and productivity of guava, nutrient management assumes greater significance. An experiment was conducted on newly planted guava cv. 'Sardar' under high density planting system (625 plants ha -1 ) to evaluate the effect of different organic (neem cake, farm-yard-manure, vermicompost) and inorganic fertilizers as well as biofertilizers (azotobacter and azospirillum) on yield and fruit quality. Maximum fruit set of 71.4% and yield of 3.49 tons ha -1 was recorded by the application of 50 g N, 40 g P 2 O 5 and 50 g K 2 O plant -1 year -1 of age along with 5 kg neem cake tree -1 year -1 during the rainy season. During the winter season the application of 50 g N, 40 g P 2 O 5 and 50 g K 2 O plant -1 year -1 of age along with 10 kg of farm-yard-manure and 20 kg of azotobacter tree -1 year -1 recorded the maximum of 45.5% fruit set. Fruit quality (total soluble solids, total sugar, acidity ascorbic acid and pectin content of fruit) in both rainy and winter seasons were found superior in fruit from the plants receiving 50 g N, 40 g P 2 O 5 and 50 g K 2 O plant -1 year -1 of age along with 5 kg of neem cake tree -1 year -1 .

GENETIC ANALYSIS IN PAPAYA (CARICA PAPAYA L.)

Analysis of various genetic characters in papaya was done during 2000 to 2002 in Randomized Block Design with four replications having two plants per replication. Evaluation of parental inbreds revealed that Pusa Dwarf (PD) was dwarf and low-flowering. Pusa Nanha (PN) flowered earlier, gave large fruits and maximum yield. Coorg Honey Dew (CHD) showed high fruit set and quality. Sunrise Solo (SS) was early flowering, had high TSS, total sugars, carotenoids and maximum shelf life. Among hybrids, CHD × PD was dwarf and recorded lower height to first flower. PN × CHD recorded maximum fruit set and earlier harvest. The highest yield per plant was in CHD × SS and SS × PD. On per se performance and combining ability analysis, the hybrids PD × CHD (dwarf, low-flowering, early bearing), PN × CHD (early bearing), CHD × SS (yield per plant, quality), SS × PD (yield per plant, fruit weight, fruit volume) and PN x PD (disease tolerance, yield per plant) were promising. PN had the highest number of dominant alleles for plant height, days to harvest, fruits per plant, yield per plant, fruit size, pulp percentage and total carotenoids. PD had the highest number of dominant alleles for plant girth, height to first flower, days to first flower, fruit weight, total sugars and shelf life. SS carried the highest number of dominant alleles for TSS and ascorbic acid, but the lowest number of dominant alleles for plant height, girth, days to first flower, pulp content, total sugars and shelf life. The study revealed that the hybrids PD x CHD, CHD × PD, SS × PD, CHD × SS and SS x CHD excelled all the other hybrids evaluated, based on their superior performance for various horticultural traits.

Visitor diversity and pollinator specialization in Mediterranean legumes

We describe the spectrum of visitors of seven Mediterranean legumes and identify the potential pollinators by observing insects’ behavior on flowers. The diversity of each population's insect assemblage (flower visitors and potential pollinators) is calculated in order to estimate to which degree pollination systems are specialized. The importance value (PI) for main taxa of potential pollinators is computed considering both insect fidelity and relative abundance. Different values of importance and dominance characterize pollinator assemblages, revealing various degrees of plant–pollinator specificity despite common papilionaceous floral traits. Visitors’ and pollinators’ diversity was negatively correlated with fruiting success, while there was a positive relation between maximum pollinator importance value and fruit set, suggesting the tendency towards a positive relationship between pollinator specificity and reproductive success.

Proximity to rainforest enhances pollination and fruit set in orchards

Summary Tropical rainforests are potential reservoirs of insects that could enhance crop pollination, but only a few instances of the provision of such services by tropical rainforest insects have been reported. Our field study aimed to determine the relative importance of such insects to the pollination of macadamia Macadamia integrifolia and longan Dimocarpus longan crops on the Atherton Tableland, north Queensland, Australia. We quantified initial fruit set, a measure of pollination success, in treatments designed to assess the relative importance of the possible modes of pollination. The treatments were applied in orchards that varied in distance from rainforest, in order to compare the effects of the contrasting pools of available pollen vectors. We also recorded the insect species present and estimated the number of visits each made to flowers in crops near and far from rainforest. For both crops there was an interaction between pollination treatment and distance from rainforest. Maximum fruit set was only achieved when pollen vectors had access to flowers and orchards were close to rainforest. Exclusion of pollinators near rainforest reduced initial fruit set to a greater extent than exclusion of pollinators far from rainforest. We confirmed that pollen transfer in macadamia is by autogamous self‐pollination and by pollen vectors, but our design did not distinguish among pollen vectors. The only abundant insects in macadamia orchards were honeybees Apis mellifera. There were more honeybee visits to macadamia flowers in orchards near rainforest than far from rainforest, but we detected no relationship between honeybee visits and initial macadamia fruit set in our sample of observations on a per raceme basis. More detailed studies are needed to identify the pollen vector responsible for enhanced pollination of macadamia near rainforest. We established for the first time that pollen transfer in longan is by a combination of autogamous self‐pollination, wind and bees. Longan flowers were visited by stingless bees and honeybees but only stingless bees had a positive relationship with initial longan fruit set and higher visitation rates near rainforest than far from rainforest. This suggests that enhanced pollination in longan near rainforest resulted primarily from a more abundant supply of stingless bees from the rainforest. Synthesis and applications. By demonstrating that tropical rainforest can act as a reservoir of pollen vectors that benefit crops, our study highlights the existence of a largely unrecognized resource available to agriculture. At the same time our results make a significant contribution to the growing database of studies that underscore the importance of tropical rainforest conservation. Policy and management aimed at sustainable use of this resource would satisfy the goals both of agriculturalists, to improve crop yields, and conservationists, to conserve tropical rainforest.

Honey Bee Pollination Requirements for Triploid Watermelon

Honey bees (Apis mellifera L.) are important pollinators of triploid watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai]. Pistillate (or female) watermelon flowers require multiple honey bee or other wild bee visitations after visiting staminate (or male) flowers for fruit set, and pollination is even more of a concern in triploid watermelon production since staminate flowers contain mostly nonviable pollen. Six honey bee visitation treatments—1) no visitation control, 2) two visits, 3) four visits, 4) eight visits, 5) 16 visits, and 6) open-pollinated control—were evaluated to determine the effectiveness of honey bee pollination on `Millionaire' triploid watermelon fruit set, yield, and quality utilizing `Crimson Sweet' at a 33% pollenizer frequency. `Millionaire' quality characters (hollow heart disorder or percent soluble solids) did not differ (P > 0.05) between honey bee pollination treatments. The open-pollinated control provided the highest fruit set rate (80%) and the greatest triploid watermelon numbers and weights per plot compared to all other honey bee visitation treatments. Fruit set, and fruit numbers and weights per plot increased linearly as number of honey bee visits to pistillate flowers increased from 0 (no visit control) to the open-pollinated control (about 24 visits). This study indicated that between 16 and 24 honey bee visits are required to achieve maximum triploid watermelon fruit set and yields at a 33% pollenizer frequency, which is twice the number of honey bee visits required by seeded watermelons to achieve similar results. This is probably due to many honey bees visiting staminate triploid watermelon flowers (that are in close proximity) before visiting pistillate flowers thus providing mostly nonviable pollen that is useless for fruit set and development. Therefore, more honey bee visits to pistillate triploid watermelon flowers would be required to achieve maximum fruit set and subsequent development compared to seeded watermelons.

Influence of Honey Bee Pollination on Triploid Watermelon Fruit Set and Quality

Cucurbit vegetable crops, such as watermelon (Citrullus lanatus), require insect pollination for fruit set, which is usually achieved by placing honey bee (Apismellifera) colonies in a field or relying upon natural bee populations. Pistillate (or female) watermelon flowers require multiple honey bee (or other bee) visitations after visiting staminate (or male) flowers for fruit set, and pollination is even more of a concern in triploid watermelon production since staminate flowers contain mostly nonviable pollen. Six honey bee visitation treatments, 1) no visitation control, 2) two visits, 3) four visits, 4) eight visits, 5) 16 visits, and 6) open-pollinated control, were evaluated to determine the effect of honey bee pollination on `Millionaire' triploid watermelon fruit set, yield, and quality utilizing `Crimson Sweet' at a 33% pollinizer frequency. No differences (P> 0.05) between honey bee pollination treatments were observed for `Millionaire' quality characters (hollow heart disorder or percent soluble solids). The lowest pistillate flower abortion rate (20%) and subsequently the greatest triploid watermelon yields (fruit numbers and weights per hectare) occurred with the openpollinated control compared to all other honey bee visitation treatments. Fruit abortion rates decreased linearly, while fruit numbers and weights per hectare increased linearly as number of honey bee visits to pistillate flowers increased from 0 (no visit control) to the open-pollinated control (≈24 visits). This study indicated that >16 honey bee visits are required to achieve maximum triploid watermelon fruit set and yields, which is twice the number of honey bee visits required by diploid watermelons to achieve similar results.

Influence of intercropping system on insect pests and viral diseases of tomato, Lycopersicon esculentum Mill.

Studies to assess the effects of intercropping in tomato under irrigated and rainfed conditions for the management of key pests at Regional Research Station, Paiyur, TamilNadu. Agricultural University, TamilNadu during 1998-2000. Experiments were conducted in a factorial randomized block design using intercrops viz, clusterbean, green gram and mustard and two rounds. of spraying with NSKE 5% and monocrotophos 0.07%, once on 30th day after transplanting and second at the time of maximum flowering and fruit set. The results revealed that tomato intercropped with mustard at 2:1 ratio had recorded reduced incidence of whitefly and thrips population and fruit borer damage as well in two different field studies. Natural incidence of tomato spotted wilt virus (TSWV) and leaf curl virus (LCV) diseases. were noticed on the rainfed tomato crop raised during August-September, 1999 planting season. The incidence of TSWV and LCV diseases were less under intercropped tomatoes than sole crop tomato and this was significantly low on the mustard intercropped plots. Nearly 30% of plants were lost due to these diseases in the tomato sole crop plots and this loss in plant population was nearly 45-60% more than the mustard intercropped plots. The combined yield of undamaged and damaged fruits was 16.319 t ha and 16.028 t ha for the sole tomato and mustard intercropped tomato under irrigated condition. However, under rainfed condition due to the severe incidence of viral diseases, an yield of 5.832 tha was recorded in sole crop while it was 8.527 t ha in mustard intercropped plots. The undamaged fruit yield recorded was 15.00 and 7.810 tha for the mustard intercropped plots, whereas it was 13.386 and 4.833 t ha for sole crop tomato under irrigated and rainfed conditions respectively. The mustard intercropping had given an additional net return of Rs.7080 and Rs.12400 because of reduced pest infestation under irrigated and rainfed conditions respectively.

Pollination of a core flowering shrub species in Mediterranean phrygana: variation in pollinator diversity, abundance and effectiveness in response to fire

Fire in Mediterranean‐type ecosystems produces catastrophic changes in plant‐pollinator systems; the recovery of which has been studied by comparing an unburnt mature forest habitat with that of an adjacent recently burnt area (eight years post‐fire). The composition, visitation profiles, and effectiveness of the taxonomically diverse pollinator assemblages found on a core nectar providing species (Saturejathymbra: Lamiaceae) were examined in these two contrasting habitats. S. thymbra in the freshly burnt area had low nectar standing crop and relatively less diverse bee community than an unburnt area which had twice the nectar standing crop and a higher bee diversity and abundance. Both sites supported bee assemblages dominated by the non‐native bumblebee Bombus terrestris. Spatio‐temporal heterogeneity of nectar standing crops and microclimatic conditions were sufficient to explain the form and magnitude of the diurnal foraging profiles at each site in relation to species specific foraging and flight abilities. B. terrestris, Apis mellifera and native solitary bees were the three primary guilds visiting S. thymbra and varied in the efficiency with which they delivered conspecific pollen grains to receptive stigmas. A pollinator effectiveness index for these three guilds was calculated based on floral visitation rates and pollen delivery efficiency and reflected the actual levels of effectiveness of each guild within and across the two habitat types. There was no overall inter‐community difference in pollination effectiveness as the bee assemblages in both habitats were sufficient to produce maximum fruit set in S.thymbra, though the relative contribution of each guild varied intra‐communally. Pollen limitation was not found to occur in either habitat.

Effect of pollen load size and source (self, outcross) on seed and fruit production in highbush blueberry cv. ‘Bluecrop’ (VACCINIUM CORYMBOSUM; Ericaceae)

Reproductive fitness of a plant is ultimately determined by both number and quality of seed offspring. This is determined by sexual selection of pollen microspores and ovules during pollination and fertilization. These processes may include pollen competition and seed abortion, which reduce the number of microspores and ovules available for final seed production. Thus, even an excess of pollen microspores to ovules does not result in fertile seeds equal to ovule number. We investigated pollen requirements of highbush blueberry (Vaccinium corymbosum cultivar 'Bluecrop') for maximal seed production and how fertile seed number translates into fruit quality, since fruit quality would ultimately determine the dispersal of its offspring. We demonstrate that individual blueberry flowers with a mean of 106 ovules reach their maximum fruit set and mass and minimum time to ripen when 125 outcross pollen tetrads pollinate a flower, compared to 10 or 25. Three hundred tetrads resulted in the increase of fertile seeds, but did not result in a further increase of fruit mass or fruit set, or decrease in time to ripen. We also examined the effect of pure and mixed loads of self and outcross pollen (25 and 125 tetrads), and found no differences in fertile seed number, fruit mass, or percentage fruit set when pollen loads were either 25 self or outcross pollen tetrads, although number of days to ripen was significantly shorter by 8 d with 25 outcross tetrads. When the pollen load of 125 tetrads consisted of self or a 50:50 mixture of self and outcross pollen, fruit mass, days to ripen, and percentage fruit set were not different from loads of 125 outcross pollen. In addition, a pollen load of 25 outcross tetrads resulted in fertile seed number and fruit quality in between that of 25 self, and 125 self, 125 mixed, or 125 outcross tetrads. Large, small, and flat seed types were identified, and only large seeds (length = 1.7 mm) were fertile. These results improve our understanding of pollen load size and source requirements of a crop plant and the limits to pollen transfer when translated to fruit growth.

115 Performance of Various Apple Scion Cultivar/Rootstock Combinations and Postharvest Fruit Quality

Several cultivar/rootstock combinations were evaluated for overall performance in Mississippi. This study included postharvest fruit quality during storage as influenced by the various rootstocks. Parameters measured were fruit set, scion and stock trunk cross-sectional area, fire blight tolerance, fruit drop, and maturity indices such as fruit size, firmness, fresh fruit weight, soluble solids content, and juice pH. Cultivar/rootstock combinations were `Earligold'/EMLA 7, `Jonagold'/EMLA 111, `Improved Golden'/EMLA 7, `Improved Golden'/EMLA 111, `Scarlet Gala' /EMLA 7, `Jonafree'/Mark, `Macspur'/M 7A, `Royal Gala'/MM 111, and `Williams Pride'/M 7A. Cultivar and rootstock influenced fruit set. `Royal Gala', `Scarlet Gala', `Improved Golden', and `Earligold' showed maximum fruit set among the various cultivars. MM 111 and EMLA 7 rootstocks increased fruit set. Scion cultivars had the greatest trunk diameter on EMLA 111 and MM 111 and the smallest diameter on Mark. Scion cultivars on Mark and M 7A rootstocks showed less susceptibility to fire blight compared to MM 111 and EMLA 111. Cultivars on EMLA 7 showed moderate susceptibility to fire blight. Cultivars `Jonafree', `Williams Pride', `Macspur', and `Scarlet Gala' were least susceptible to fire blight compared to `Royal Gala'. The remaining cultivars were intermediate in susceptibility to fire blight. Fruit size, firmness, fresh fruit weight, soluble solids content, and juice pH were influenced by cultivar. `Jonagold' and `Williams Pride' produced the largest fruit, while `Jonafree' and `Macspur' yielded the smallest fruit. Total soluble solids were not influenced by cultivar and rootstock combinations. Sugar content of the juice increased as the apples matured and ranged from 12% to 14% among the cultivar/rootstock combinations. Firmness was influenced by cultivar but not rootstock. `Jonafree', `Macspur' had firm fruit, while fruit of `Scarlet Gala', `Williams Pride', and `Earligold' was not as firm. After harvest, the cultivars were stored at 2 °C for ≈4 months under controlled conditions and evaluated for soluble solids content, titratable acidity, pH, and firmness at monthly intervals. Overall, firmness, soluble solids content, and titratable acidity in all cultivars decreased with time in storage. `Improved Golden'/EMLA 7, `Royal Gala'/MM 111, and `Jonagold'/EMLA 111 maintained quality during storage, compared with the remaining cultivars/rootstock combinations, and had a longer storage life.