Effect of temperature on pollen germination and pollen tube growth of four cultivars of mango (Mangifera indica L.)

Summary

The effect of a constant (10, 15, 20 or 25°C) or a diurnal maximum/minimum (15/5, 20/10, 25/15 or 30/20°C) incubation temperature on in vitro pollen germination and pollen tube growth in the pistils of two poly-embryonic (‘Kensington’ and ‘Nam Dok Mai’), and two mono-embryonic (‘Irwin’ and ‘Sensation’) mango cultivars was studied. In in vitro experiments where pollen was incubated in a liquid germination medium for 24 h in darkness, little difference was found between pollen germination of mono- and poly-embryonic cultivars. Averaged over the four cultivars, 53.9% of pollen germinated at 10°C, this increased to 76.2% when the incubation temperature was increased to 15°C, thereafter up to 25°C the percentage germination remained stable but germination decreased slightly to 68.2% at 30°C. Similarly, there was no difference in percent germination between cultivars when pollen was incubated under diurnal temperature regimes. Mean pollen germination of all four cultivars was 52.3% at 15/5°C and pollen germination increased by 10% when the temperature was raised to 30/20°C. When self-pollinated flowers were incubated for 24 h on a semi-solid agar medium at 10°C, pollen tube growth of the four cultivars was retarded and no pollen tubes reached the ovaries. As the temperature was increased from 15 to 25°C, the mean number of pollen tubes in ovaries increased from 0.04 to 0.25. At 30°C, the mean number of pollen tubes that entered ovaries decreased to 0.04. After incubation under diurnal temperature regimes, the mean number of pollen tubes in ovaries of all four cultivars at 15/5°C was 0.23 and increased to 0.42 when the temperature increased to 30/20°C. At each incubation temperature, there were significant differences in pollen tube growth between cultivars, but there were no differences between the temperature response of pollen from mono- and poly-embryonic cultivars.     

The effect of temperature on certain chemical changes and the storage behaviour of jujube fruits (Zizyphus spinachristi (L.), Willd.)

Summary

Jujube fruits (Zizyphus spinachristi (L.) Willd.) cv. Bambawi were harvested at the mature green stage and stored at 10°C and 27–30°C. Titratable acidity and total chlorophyll decreased as the fruit matured, the rate of decline being more rapid at the higher temperature. Total soluble solids, carotenoids and ascorbic acid contents of the fruit increased towards maturity, the increase being faster at the higher temperature. Jujube fruits could be stored for six days at room temperature and twenty-five days under refrigeration at 10°C.     

Effect of pistil age and pollen parent on pollen tube growth and fruit production of pistachio

Female pistachio (Pistacia vera) trees were hand pollinated with pollen from three different male genotypes 0,1,2,3 and 4 d after anthesis. Results were measured by mature fruit set and by fluorescence microscopy of pollen germination and tube growth in the pistil. Maximum pollen tube growth and fruit set of split nuts was achieved following pollination within two days of anthesis. Three day old pistils supported pollen tube growth, but fruit set was low. Four day old pistils supported little pollen tube growth or fruit set. Significant differences were also apparent between pollen parents, with low pollen tube growth and fruit set following interspecific pollination with P. atlantica pollen. All pollen tubes were observed to penetrate chalazogamously, and parthenocarpic production of blank fruits occurred in both unpollinated and pollinated treatments. The results indicate that for optimum fruit production of pistachio, pollen transfer must be achieved within 2 d of anthesis and pollination by P. atlantica should be avoided.     

Long-term storage of yam pollen

During 1978–1979, viability of mixed hand-collected pollen from 6–10 genotypes of white yam (Dioscorea rotundata Poir.), stored under various combinations of relative humidity (Rh) and temperature, as well as the relation of pollen germination in vitro with fruit set were investigated.Yam pollen stored at 0% RH, ?5°C, remained highly viable for over one year (from one flowering-season to the next). Fluctuations in storage conditions accelerated loss of pollen viability. Pollen germination in vitro was not significantly correlated with the degree of fruit set, and pollen samples with low percent germination did give satisfactory fruit set.     

Growth of Vitis vinifera L. and Vitis aestivalis Michx. as Affected by Temperature

Abstract

Four European (Vitis vinifera L.) winegrape cvs., ‘Semillon’, ‘Pinot Noir,’ ‘Chardonnay’, and ‘Cabernet Sauvignon’, and one American (Vitis aestivalis Michx.) winegrape cv. ‘Cynthiana’, were subjected to three temperature regimes in growth chambers set at 20/15°C, 30/ 25°C, or 40/35°C, for 16/8 hr day/night to determine the influence of temperatures on vine growth and development. In general, the best temperature for shoot and root growth 28 days after temperature treatments was 20/15°C for ‘Semillon’, ‘Cabernet Sauvignon’, and ‘Cynthiana’, and 30/25°C for ‘Pinot Noir’ and ‘Chardonnay’. Although 40/35°C reduced number of leaves, shoots, tendrils, and internodes, total leaf area (LA), and total shoot biomass of all the cultivars, the reduction was more pronounced in ‘Cynthiana’ than in the European cultivars. The average reduction in number of leaves at 40/35°C for the European cultivars was 47%, compared with 92% for ‘Cynthiana’. The two types of grapes adapted differently to high temperature. Shoot growth in the European cultivars continued under high temperature, whereas growth ceased in ‘Cynthiana’. Roots of ‘Cynthiana’, however, were less susceptible to the adverse effect of high temperatures than were the shoots. This study shows that the European cultivars were relatively more tolerant to high temperature than the American cultivar and they have a potential for production of wine in the climate of south central Kansas.     

Effects of low temperatures on sexual reproduction of ‘Tainong 1’ mango (Mangifera indica)

Prevailing ambient temperature during the reproductive phase is one of important factors for seed and fruit set in different plant species. In mango (Mangifera indica L.), natural low temperatures during flowering induced seedless fruits. Here the sexual reproduction process of ‘Tainong 1’ mango at low temperatures (diurnal maximum temperature < 20 °C) was studied. For comparison, we also examined this process at “normal” temperatures (diurnal maximum ranging from 25 to 30 °C, diurnal average temperature > 20 °C). Results showed: natural low temperatures significantly affected pistil and male gametophyte development, resulting in pollen grains with low viability. Meiotic chromosomal irregularities, including univalents, multivalents, laggards, bridges and micronuclei were detected at higher incidences and significantly greater proportions of nucleolus fragmentation and dissolution were detected when temperatures were low. Pollen tube growth was retarded under low temperature stress, either in vivo or in vitro. The virtual absence of sexual reproduction of ‘Tainong 1’ mango at low temperatures appears to be due largely to slow growth of pollen tube in vivo and to a low rate of successful fertilization.     

The Effect of Temperature on Floral Behaviour,Pollen Tube Growth and Fruit Set in the Avocado

Avocado plants were kept in growth cabinets at 33°C day, 28°C night (33/28); 25°C day, 20°C night (25/20); and 17°C day, 12°C night (17/12), with a 12-h photoperiod and light intensity of 26000 1x. At 33/28 and 25/20 flowers opened in the afternoon as females and again the following morning as males (type B floral cycle) with some overlap of male and female stages at 25/20. At 17/12 very few flowers had a female stage, the majority opening once only as males. The duration of the flowering period decreased with a rise in temperature as did total number of flowers opening. Reproductive growth was inhibited in favour of vegetative growth at 33/28, as exhibited by smaller floral parts and abscission of buds and flowers. The rate of pollen tube growth increased with a rise in temperature, but abnormal growth was frequently observed at 33/28 and tubes failed to reach the ovary at 17/12. Endosperm and embryo development was observed to occur at 25/20 but not at 33/28 or 17/12 although a positive effect of pollination on fruit retention was evident at 33/28. This effect also occurred at 25/20 but not at 17/12. The most suitable temperature regime for floral behaviour, pollen tube growth and embryo development was 25/20.     

Leatheriness and mealiness of peaches in relation to fruit maturity and storage temperature

Summary

`Huangjin' peaches (Prunus persica Batsch) were harvested at commercial harvest time (commercial) and 20 d before (early) or after (later) commercial harvest. Fruit from each harvest were stored at three temperature regimes (0, 5 and 10°C) at 95% r.h. After four weeks of storage at 0 or 5°C, early harvested fruit developed more leatheriness but less mealiness and later harvested fruit did not develop leatheriness but developed more mealiness comparedwith fruit from commercial harvest. Overall, fruit stored at 5°C developed more mealiness but less leatheriness than fruitat 0°C for the same period of storage. When stored at 10°C for two weeks, after which fruit were senescent, fruit did not develop any leatheriness or mealiness regardless of harvest times. Fruit with leatheriness were firmer (>30 N) thanjuicy or mealy fruit (<10 N) after the same period of cold storage and 4 d at 20°C. Mealy fruit were as soft as juicy fruit. 1-Aminocyclopropane-1-carboxylate oxidase (ACO) activity, 1-aminocyclopropane-1-carboxylic acid (ACC) content, and polygalacturonase (PG) and galactosidase (GAL) activities were lower, and insoluble pectin content was higher in leathery fruit than that in juicy or mealy fruit. ACO, PG and GAL activity, ACC, and insoluble pectin content were similar between mealy and juicy fruit.     

Pollen tube growth in styles of apple and almond flowers after spraying with pesticides

Summary

The timing of fungicide and antibiotic applications in fruit crops often overlaps flowering and pollination. Numerous studies report detrimental effects of chemical applications on pollination, fruit set and yield. However, field results can be quite variable even when similar compounds are tested on the same crop. Problematic is that field variables unrelated to the effects of pesticides on reproductive activities can mask results. In the current study, we specifically investigated the effects of selected pesticide sprays applied to stigmas, on subsequent pollen germination and tube growth. Using two model systems, apple and almond, sprays were applied to detached emasculated flowers under constant laboratory conditions using an electronically controlled robotic apparatus which simulated a field sprayer. flowers were pollinated at specific times after spraying, and pollen tube numbers and growth assessed using fluorescence microscopy. The pesticides evaluated were for apple: captan, myclobutanil and streptomycin; and for almond: azoxystrobin, myclobutanil, iprodione and cyprodinil. In apple, captan significantly reduced pollen germination, by 20% compared with water controls when pollination was conducted 18 h after treatment. The number of tubes that reached the basal part of the style within 20 h was not affected. In contrast, myclobutanil and streptomycin had no significant effect on pollen tube growth. With almond, none of the sprays significantly affected pollen germination or tube growth.     

The pattern and control of reproductive development in lychee: A review

Often there is no relationship between yield and flower production in lychee (Litchi chinensis Sonn,). This is because of the high rate of premature flower and, especially, fruit abscission between floral initiation and fruit maturation. There is the possibility that low female-to-male sex ratio, lack of pollinating insects, poor pollen transfer, low pollen viability and failure of pollen tube growth may also reduce fruit set, while poor fruit development may reduce final fruit size.Detailed studies are required on the effects of genotype and environment (temperature, soil moisture, humidity and mineral nutrition) on the growth and abscission of the flowers and fruit. Potential techniques for improving the setting and retention of fruit include varietal selection, withholding of nitrogen fertilization during flowering and early fruit growth (to reduce vegetative flushing), and the maintenance of plant moisture status (irrigation, overhead misting and windbreaks).     

Maturity of apple cv. Elstar as affected by temperature during a six-week period following bloom

Summary

In two experiments under controlled conditions, the effect of temperature (16, 20 and 24°C, experiment 1; 16 and 22°C, experiment 2) during a six-week period immediately following bloom on the progress of ripening around the normal picking time was evaluated for fruits of cv. Elstar. After six weeks, the temperature in experiment 1 was kept at 20°C throughout. In experiment 2 the temperature was 22°C from week 6 to 14, and 16 or 22°C from week 14 to 22. Post-bloom temperature clearly affected the rate of fruit ripening as reflected in ethylene production, background colour, starch content, firmness and red blush, but these variates did not respond to the same degree. The effect of temperature late in the season on ripening (just during the maturation period) was almost absent when the post-bloom temperature was 16°C. However, when post-bloom temperature was 22°C, fruits were greener, firmer, contained more starch and showed more red blush at 16 than at 24°C given from week 14 to 22. The acid content at ripening was lower at the higher post-bloom temperatures. Irrespective of the post-bloom temperature, acid content was also reduced at the higher temperature given during the maturation period. The content of soluble solids showed no consistent pattern.     

Flowering and fruit-set response to temperature in the avocado cultivar ‘Hass’

Avocado plants, cultivar ‘Hass’, were kept in growth cabinets at 33°C day, 28°C night ($\text{33}\text{28}$); 25°C day, 20°C night ($\text{25}\text{20}$); and 17°C day, 12°C night ($\text{17}\text{12}$), with a 12-h photoperiod and photon flux density of 400 μE m^?2 s^?1 (400–700 nm). At $\text{33}\text{28}$ and $\text{25}\text{20}$ flowers opened in the morning in the female stage and again in the afternoon of the following day in the male stage (Type A floral cycle). At $\text{17}\text{12}$ the flowers opened in the afternoon in the female stage and started to reopen in the male stage 2 days later during the afternoon. They remained open overnight and started to close the following morning. Pollen tube growth and ovule penetration occurred at all temperatures. Pollen tube growth was fastest at $\text{33}\text{28}$, but the pistils had lost the ability to support pollen tube growth by the second week of the experiment. A lower proportion of the ovules at $\text{17}\text{12}$ had an embryosac penetrated by a pollen tube. Embryo development occurred at all temperatures, but fruitlets were abscissed at $\text{33}\text{28}$ and embryo growth was very slow at $\text{17}\text{12}$. The most suitable temperature regime for floral behaviour, pollen tube growth and embryo development was $\text{25}\text{20}$.     

Papaya pollen viability and storage

Papaya pollen viability, tube growth and storage were studied. Pollen germination on a drop of modified Brewbaker medium at 22–26°C closely reflected in vivo germination. Two vital stains gave pollen viability estimates that correlated closely with pollen germination percentage. The time from pollination to first ovule penetration was 25 h at 28°C, no in vitro pollen germination was observed at 5°C and at 40°C pollen tube growth was retarded. High relative humidity (70–80%) hastened the process compared with low relative humidity (30–40%).

Pollen could be stored successfully for 6 months when kept at − 18°C in a deep-freezer. Storage of pollen for the winter months, during which no or very little viable pollen is formed in the coastal area of Israel, seems a practical means to ensure adequate fruit set.     

Effects of pre-blossom temperatures on flower development and fruit set in apricot

The influence of pre-blossom temperatures on flower development and fruit set is ascertained in apricot (Prunus armeniaca L.), a species without previous records on the effect of pre-blossom temperature on fruit set, but that is particularly prone to erratic fruit set. A polyethylene cage was used during pre-blossom development of flower buds to increase maximum temperatures by 6–7 °C and mean temperatures by 3 °C in orchard conditions. This increase in temperature accelerated flower bud development, caused a hastening in flowering time and following hand-pollination, reduced fruit set. At anthesis, flowers that had developed in warmer conditions weighed less and showed less development of the pistil than control flowers. Pistil growth of flowers under warm conditions did not differ from that of the control flowers when both the populations were compared on a real time scale in spite of the fact that warmed buds were at an advanced external phenological stage. Thus, hastening of external floral development by warm pre-blossom temperatures was not accompanied by advance in pistil development. This lack of synchrony resulted in premature flowering of flowers with underdeveloped pistils that had a reduced capability to set fruit. The results are discussed in terms of flower quality and its implications in fruit set and subsequent crop load.     

Amount of Cortical and Epidermal Tissue Shed From Roots of Apple

Rates of CO₂ production by cv Idared apples were progressively reduced by lowering O₂ levels from 21% to 2% and 1%. Although lowering the temperature from 4° to 2°C also reduced the respiration rate, fruits stored in 1% and 2% O₂ were respiring faster after 100 days at 0°C than at 2° or 4°C. After 192 days the air-stored fruit also showed an increase in respiration rate at 0°C. These higher respiration rates preceded the development of low temperature breakdown in fruit stored in air, 2% and 1% O₂ at 0°C and in 1% 0₂ at 2°C. Progressively lower O₂ concentrations reduced ethylene production whilst increasing the retention of acid (expressed as malic), soluble solids, chlorophyll and firmness. In the absence of low temperature breakdown the effects of reduced temperature on fruit ripening were similar to those of lowered O₂ concentrations. The quality of apples stored at 4°C in 1% O₂ was markedly better than in 2%; the fruits were also free of core flush (brown core) and other physiological disorders.     

Effect of temperature on growth,dry matter production and starch accumulation in ten mango (Mangifera indica L.) cultivars

Summary

Ten mango cultivars of tropical and subtropical origin (Carabao, Kensington, Nam Dok Mai, Alphonso, Dashehari, Florigon, Glenn, Irwin, Haden and Sensation) were grafted onto cv. Kensington seedling rootstock and held at four day/night temperatures for 20 weeks (15/10°C, 20/15°C, 25/20°C and 30/25°C). Vegetative growth increased with increasing temperatures. All grew vegetatively at 25/20°C and 30/25°C. Cultivars which did not grow at 20/15°C were Carabao, Kensington and Dashehari. Cultivars Kensington, Nam Dok Mai, Alphonso, Florigon, Glenn, Irwin, Haden and Sensation produced flower panicles at 15/10°C. The rise in temperature increased the average number of growth flushes (in responsive cultivars) from 0.48 at 15/10°C to 3.21 at 30/25°C, and the number of leaves per growth flush (1.22 at 15/10°C to 13.63 at 30/25°C). Distribution of dry matter from new growth was mostly to the roots at the lowest temperature (95% at 15/10°C) and to the leaves (58%) at 30/25°C. The mean daily temperature for zero vegetative growth was calculated to be 15°C. Temperature and related growth activity also affected the concentration of starch in the woody tissue of rootstock trunks at the end of 20 weeks (15.9% starch at 15/10°C v. 4.8% starch at 30/25°C). ‘Irwin’ had the highest starch concentration at the two higher temperatures (twice that of any other cultivar at 30/25°C) while ‘Kensington’ the lowest starch level at 25/20°C, ca. 50% of most other cultivars.     

Differential propylene induced ethylene production in ‘Anjou’ pears during storage at chilling and non-chilling temperatures

Summary

‘Anjou’ pears were harvested from the Mid-Columbia Experiment Station, Hood River, Oregon, at 67 N firmness, stored at –1° or 20°C for 85 d and periodically tested for sensitivity to 0 or 500 µl l^?1 propylene for at least 14 d at 20°C. Climacteric ethylene of pears stored at 20°C remained at low levels and started rising on the 90th day. Pears chilled at –1°C required 70 d to ripen and produced climacteric ethylene immediately upon transfer to 20°C. The sensitivity of the fruit to exogenous propylene increased progressively with storage time at –1°C. However, the non-chilled fruit responded to propylene similarly to freshly harvested fruit during the first 55 d of storage, then similarly to –1°C-stored fruit up to 85 d. Anjou pear ripening events and the sensitivity of the fruit to exogenous propylene developed differently in storage at non-chilling temperature compared with chilling temperature.     

Prevention of hot-water treatment damage in narcissus bulbs by pre-warming

Summary

Hot-water treatment (HWT) used to control stem nematode in narcissus bulbs can lead to yield loss through damage to flower, leaf and root initials. Warm storage of bulbs, usually at 30°C, reduces this damage. The effects of two pre-warming treatments (18°C for two weeks or 30°C for one week before HWT) were investigated in bulbs hot-water treated at a range of dates (from early-July to late-September). Experiment 1 was conducted on bulbs of cv. Carlton lifted on three dates. In the year after HWT, flower numbers were much reduced when HWT was applied after mid-August following storage at ambient temperatures, or after late-August following storage at 30°C, but numbers were only slightly reduced even with late-September HWT when given after 18°C storage. Pre-warming was somewhat more effective after early lifting. Late HWT reduced yields of bulbs harvested after two years' growth, but 18°C treatment largely prevented these losses. In Experiment 2, the beneficial effects of 18°C treatment were confirmed in cvs Carlton and Golden Harvest but not in cv. Barrett Browning. These findings are discussed in terms of growth retardation by warm temperatures.     

Interactions between root-zone temperature and light levels on growth,development and photosynthesis of Lycopersicon esculentum Mill. cultivar ‘Vendor’

Six-week-old tomato plants were subjected to 5 root-zone temperatures, ranging from 12 to 36°C, and 4 light levels in a factorial design. Large increases in shoot dry weight, leaf area and fruit development resulted from soil warming to 24°C when plants were grown under high light conditions. Shoot growth and fruit weight were reduced at 24°C root temperature under low light conditions. Total plant photosynthesis, leaf area index, net assimilation rates and leaf chlorophyll content were related to plant growth and flower development for the various treatments. Our experiments have shown an interaction between root-zone temperature and light levels for greenhouse tomatoes. Soil warming caused large increases in shoot dry weight and fruit development when light was not limiting plant growth, but had deleterious effects on flowering and fruit set under shaded conditions.     

The effect of ε-aminocaproic acid on self-incompatibility and incongruity in Phaseolus

Summary

The effects of ε-aminocaproic acid (EACA) on self-incompatibility was tested in a Phaseolus coccineus line which failed to form pods in controlled pollinations. Scanning electron microscope (SEM) and fluorescence miscroscopy confirmed problems in pollen-germination and pollen-tube growth but EACA-treated self- pollinations resulted in fairly normal pollen germination and pollen tube growth. In a few cases, pollen tubes were seen entering the embryo sac and occasionally pods were formed. Incongruity barriers also exist in crosses of P. coccineus × P. vulgaris, P. acutifolius × P. coccineus and their reciprocals. Effects of EACA on flower abscission, pod development and pod abscission were studied. Increased pod formation was observed in EACA treated materials, except in P. acutifolius × P. coccineus and P. coccineus × P. vulgaris cv. Jacobs Cattle. EACA seems to act at the stigmatic and stylar levels, thereby enhancing pollen germination and pollen tube growth and delaying flower abscission. The net result is fertilization and delayed senescence which permit the pod to grow for a longer period of time.