Warm Growing Conditions Research Articles

Photosynthesis rate, radiation and water use efficiencies of irrigated potato in a semi-arid climate using Eddy covariance techniques

AbstractUnderstanding the photosynthetic behaviour, radiation use efficiency (RUE) and water use efficiency (WUE) of potatoes in response to diurnal and seasonal fluctuations in weather, is important for optimizing growth and production. The net ecosystem exchange (NEE) of carbon dioxide (CO2), is a parameter used to measure the balance between gross CO2 assimilation (also referred to as gross primary production (GPP)) and ecosystem respiration (Reco). The objectives of this study were (i) to quantify the NEE of potato grown in two contrasting agro-ecologies and partition NEE into Reco and GPP; (ii) to describe seasonal patterns in daily photosynthesis, RUE and WUE in potato; and (iii) to analyse the variability in photosynthesis rate, RUE and WUE as affected by weather and crop growth stage. We measured CO2 and water vapour fluxes using eddy covariance techniques in potato fields in two production regions of South Africa. The winter crop had higher mean RUE and WUE values, whereas the summer crop absorbed more CO2. RUE had a negative relationship with incident radiation. To optimize dry matter production, WUE and RUE, potato crops must be well established and develop a full canopy early during the season. Maintaining the crop for a longer period in the field has yield benefits, although they appear to decline over time due to reduced efficiencies as the crop matures. The RUE observed over the growing period in the present study was high, relative to findings by other field studies, despite relatively warm growing conditions that were likely sub-optimal for potato.

Bulb growth potential is independent of leaf longevity for the spring ephemeral Erythronium americanum Ker-Gawl.

Growth in most spring ephemerals is decreased under warmer temperatures. Although photosynthetic activities are improved at warmer temperatures, leaves senesce earlier, which prevents the bulb from reaching a larger size. A longer leaf life duration during a warm spring, therefore, may improve bulb mass. We tested this hypothesis by modulating leaf life span of Erythronium americanum through the application of Promalin® (PRO; cytokinins and gibberellins) that prolonged or silver thiosulfate (STS) that reduced leaf duration. Gas exchange and chlorophyll fluorescence were measured along with leaf and bulb carbohydrate concentrations. Plants were also pulse labelled with 13CO2 to monitor sugar transport to the bulb. Lower photosynthetic rates and shorter leaf life span of STS plants reduced the amount of carbon that they assimilated during the season, resulting in a smaller bulb compared with control plants. PRO plants maintained their photosynthetic rates for a longer period than control plants, yet final bulb biomass did not differ between them. We conclude that seasonal growth for E. americanum is not limited by leaf life duration under warm growing conditions, but rather by limited sink growth capacity. Under global warming, spring geophytes might be at risk of being reduced in size and, eventually, reproducing less frequently.

Severe trimming and enhanced competition of laterals as a tool to delay ripening in Tempranillo vineyards under semiarid conditions

Aim: An advance in grapevine phenological stages (including ripening) is occurring worldwide due to global warming and, in the hottest seasons, already results in a lack of synchrony between sugar and phenolic ripeness, leading to unbalanced wines. In order to cope with this fact, a general effort is being made by researchers and growers aiming at delaying ripening through cultural practices, particularly under warm growing conditions, where these effects are more deleterious. The aim of this work is to evaluate to which extent severe trimming and enhanced competition of laterals can delay ripening in Tempranillo vineyards under semiarid conditions.Methods and results: The experiment took place during two consecutive seasons in Traibuenas (Navarra, Spain) in a cv. ‘Tempranillo’ vineyard trained to a vertical shoot positioned (VSP) spur-pruned bilateral cordon. Severe mechanical pruning was performed ca. 3 weeks after fruit-set in order to reduce leaf-to-fruit ratio, and in the trimmed plants, three irrigation doses were applied until harvest aiming at enhancing lateral growth, hypothesized to compete with ripening. All measurements were performed in six 10-vine replicates per treatment. Trimming significantly reduced leaf area and yield, resulting in higher water availability in trimmed plants. The whole ripening process was delayed by trimming: mid-veraison was delayed by about 5 days, and the delay in sugar accumulation and acid degradation was longer, differences being more marked in malic than in tartaric acid concentration. The use of increased irrigation levels compensated the losses in yield caused by trimming, enhanced laterals’ growth and implied an additional delay in ripening.Conclusion: trimming and increased irrigation had an additive effect in terms of delaying ripening, and they can be used jointly when that delay is needed.Significance and impact of the study: this study proves the potentiality of the joint use of trimming and increased irrigation to delay ripening, although it is necessary to analyze the implications the obtained delay has on other quality aspects. The lower anthocyanin and phenolic values observed in trimmed vines were not solely due to delayed ripening, as lower values were observed even when data were compared for a given total soluble solid content.

Severe trimming and enhanced competition of laterals as a tool to delay ripening in Tempranillo vineyards under semiarid conditions

<p style="text-align: justify;"><strong>Aim:</strong> An advance in grapevine phenological stages (including ripening) is occurring worldwide due to global warming and, in the hottest seasons, already results in a lack of synchrony between sugar and phenolic ripeness, leading to unbalanced wines. In order to cope with this fact, a general effort is being made by researchers and growers aiming at delaying ripening through cultural practices, particularly under warm growing conditions, where these effects are more deleterious. The aim of this work is to evaluate to which extent severe trimming and enhanced competition of laterals can delay ripening in Tempranillo vineyards under semiarid conditions.</p><p style="text-align: justify;"><strong>Methods and results:</strong> The experiment took place during two consecutive seasons in Traibuenas (Navarra, Spain) in a cv. ‘Tempranillo’ vineyard trained to a vertical shoot positioned (VSP) spur-pruned bilateral cordon. Severe mechanical pruning was performed ca. 3 weeks after fruit-set in order to reduce leaf-to-fruit ratio, and in the trimmed plants, three irrigation doses were applied until harvest aiming at enhancing lateral growth, hypothesized to compete with ripening. All measurements were performed in six 10-vine replicates per treatment. Trimming significantly reduced leaf area and yield, resulting in higher water availability in trimmed plants. The whole ripening process was delayed by trimming: mid-veraison was delayed by about 5 days, and the delay in sugar accumulation and acid degradation was longer, differences being more marked in malic than in tartaric acid concentration. The use of increased irrigation levels compensated the losses in yield caused by trimming, enhanced laterals’ growth and implied an additional delay in ripening.</p><p style="text-align: justify;"><strong>Conclusion: </strong>trimming and increased irrigation had an additive effect in terms of delaying ripening, and they can be used jointly when that delay is needed.</p><p style="text-align: justify;"><strong>Significance and impact of the study:</strong> this study proves the potentiality of the joint use of trimming and increased irrigation to delay ripening, although it is necessary to analyze the implications the obtained delay has on other quality aspects. The lower anthocyanin and phenolic values observed in trimmed vines were not solely due to delayed ripening, as lower values were observed even when data were compared for a given total soluble solid content.</p>

Multi-locational evaluation of Linseed (Linum usitatissimum L.) germplasm under rainfed ecology

Field experiments were conducted at three locations in augmented design during the winter season of 2008 allowed for the assessment of broad adaptation to dry and warm growing conditions of 100 linseed (Linum usitatissimum L.) accessions. Perusal of resultsrevealed that there exists sufficient genetic variability for seed yield in the studied linseed accessions. Sagar was adjudged best among the locationsfor harvesting a good yield. EC 704, an exotic line recorded highest seed yield at Sagar and Latur whereas, EC 1066, EC 1534 and EC 1466 recorded higher seed yield than the best check at all the three experimental sites showing a sign of wide adaptation. Such an approach to make efficient use of germplasm collections remains important even today. This contribution summarizesthat genotypes EC 704, EC 1066, EC 1534 and EC 1466 having stable yield potential may be exploited in the linseed breeding programme to combat global climate change.

Influence of Temperature Manipulation during the Last 4 Days of Incubation on Hatching Results, Post-Hatching Performance and Adaptability to Warm Growing Conditions in Broiler Chickens

Two incubation and two growing trials were carried out. A total of 1000 (Trial 1) and 1897 (Trial 2) eggs of the ROSS (308) strain were incubated from d 1 to 17 under normal conditions and from d 18 until hatch as follows: 37.2 to 37.4°C (control), 38.2 to 38.4°C for 24h daily (chronic warm incubated) and 38.2 to 38.4°C for 2h daily (short term warm stimulated). In incubation Trial 2, the chickens were sorted by sex. Chick quality was analysed by the Pasgar score. In the 35 day growing Trial 1, a total of 240 one day old chickens and in Trial 2 a total of 120 male and 120 female chickens from all incubation groups were kept at 34°C at d 1 and 2, and from d 3 up to the age of 35 days, at 32°C. The results of the two incubation trials showed that chronic or short-term increase in incubation temperature at the end of incubation did not diminish hatchability and chick quality. The data indicates different effects of chronic and short-term warm incubation as well as warm growing conditions on the performance of female and male broiler chickens. Female chickens seem to be better adapted to warm growing conditions and show a higher tendency in performance parameters (feed intake, body weight gain, and body weight) during the final growing period. In male chickens exclusively chronic warm-incubation leads to a lowered daily feed intake in the final growing period which results in the lowest fattening weight of 1332g per animal (control: 1476g, short term warm incubated: 1482g). A lower feed intake decreases the bodily heat production and can help to minimize heat stress. At slaughtering (Trial 2), the percentages of breast meat, liver, heart, stomach, spleen and fat showed no statistical difference between the groups or sexes.

Effect of temperature on gametophytic selection in a Phalaenopsis F1 population

Gametophytic selection has potential to increase the efficiency of breeding for temperature tolerance. Here, we describe orchid seedlings after application of low and high temperatures during gametophytic development. In addition to phenotypic traits, amplified fragment length polymorphism (AFLP) markers were used to determine the genetic variability in seedlings. Two hybrid Phalaenopsis were cross-pollinated and exposed to 30°C day/25°C night for 3 days for a warm pollination or 15°C day/10°C night for 7 days as a cold pollination treatment. The plants were returned to the greenhouse after pollination and green capsules were collected after 150 days. Protocorms obtained from these treatments were evaluated 72 days after initial plating for germination and size on a thermogradient table ranging from 10 to 30°C. Seedlings were then evaluated 1 year after initial plating. The mean number of roots per seedling (4.2) was greater for plantlets that derived from the cold pollination treatment compared to those from warm pollination (3.6). Weight of the seedlings, number of roots and the average root length were significantly affected by the interaction between pollination treatment and germination temperature. The weight, number of leaves, and average root length were significantly affected by the interaction between pollination treatment and incubator/growth chamber. The results indicated that seedlings derived from warm pollination were more vigorous under warm growing conditions and those derived from cold pollination were more vigorous under cold growing conditions. Genetic variation among 16 F1 seedlings randomly selected from various temperature treatments was analyzed. A dendrogram based on 651 loci resulted in three major groups and one subgroup. The groups and subgroup revealed common selection pressure during the gametophytic stage. The AFLP data support genetic differentiation of Phalaenopsis hybrids pollinated under different temperatures.

Nutrient demand and uptake by pickling cucumber under drip irrigation in a northern climate

SummaryHigh yield and quality of pickling cucumber require an even supply of nutrients. Under drip irrigation, nutrient supply can be optimised according to the plant’s needs, and losses to the environment can be minimised. This research aimed to determine which nutrients are needed in fertigation, the optimal dosages of nitrogen for pre-planting fertilisation and fertigation, and the level of nutrient uptake by cucumber plants in a northern climate. A relatively low nitrogen dose (120-140 kg ha–1) was sufficient for good yield. Under warm growing conditions, a higher nitrogen dose increased yield, but only by 5%. Addition of N and K by fertigation was sufficient when other nutrients were provided by pre-planting fertilisation. Nutrient uptake per tonne of fruit was 1.2–1.4 kg N, 0.28–0.35 kg P and 2.2 kg K, which were slightly lower than reported in earlier studies. Our results indicate that high cucumber yields can be obtained by moderate fertilisation when drip irrigation and fertigation are used.

Vernalization in Arabidopsis thaliana is mediated by the PHD finger protein VIN3.

In biennials and winter annuals, flowering is typically blocked in the first growing season. Exposure to the prolonged cold of winter, through a process called vernalization, is required to alleviate this block and permit flowering in the second growing season. In winter-annual types of Arabidopsis thaliana, a flowering repressor, FLOWERING LOCUS C (FLC), is expressed at levels that inhibit flowering in the first growing season. Vernalization promotes flowering by causing a repression of FLC that is mitotically stable after return to warm growing conditions. Here we identify a gene with a function in the measurement of the duration of cold exposure and in the establishment of the vernalized state. We show that this silencing involves changes in the modification of histones in FLC chromatin.

Interaction of Late Season Foliar Spray of Urea and Fungicide Mixture in Wheat Production

AbstractNitrogen (N) fertilization with foliar urea and fungicide treatment at flag leaf emergence (GS 47) are common strategies to improve both grain yield and quality in wheat (Triticum aestivum L.). Mixing of urea and a fungicide, together, would save time in farm operations. In some cases, the effect of foliar sprayings of urea either alone or in combination with a fungicide may, however, give unexpected low response to grain yield and quality when compared to separate application of foliar urea and fungicide. This study was designated to provide more detailed information about the effects of late‐season spraying of urea (15 kg N ha−1 as an aqueous solution of 110 g l−1) alone or mixed with fungicide (propiconazole, 125 g ha−1) on the grain yield and grain protein content of spring wheat. To avoid foliar injury or phytotoxic effect of foliar spray of urea, mixing of urea with propiconazole in warm growing conditions should be avoided. In turn, during cool and rainy growing season, a mixture of these two chemicals is recommended in order to improve rapid absorbtion of both propiconazole and foliar urea. However, the genotypic differences were recorded in response to propiconazole and urea sprayings. The positive effects on cultivars of these chemicals were attributed to high leaf photosynthesis rate after propiconazole and foliar urea treatment and high leaf urease enzyme activity after foliar urea application.

EFFETS DES RÉGIMES THERMIQUES ET HYDRIQUES, DES pH DU SOL ET DE LA FUMURE PHOSPHATÉE SUR LA RÉPONSE AU PHOSPHORE DE LA LUZERNE

The objectives of this study were to determine the effects of phosphorus application, air temperature, soil moisture regime and soil pH on the yield response of, and soil phosphorus availability to, alfalfa (Medicago sativa L ’Saranac’). The following treatments were used in factorial combination: three moisture regimes: (1) semi-dry, with soil moisture between FC (100% of available water or field capacity) and WP (0% of available water or wilting point), (2) optimal, between FC and 70% of available water, (3) wet, between saturation point and FC; three rates of phosphorus in the form of disodium phosphate (0, 12.5 and 25.0 P kg−1 of dry soil; and three soil pH levels: original (5.2 or 5.7), 6.5 and 7.5. Half of the alfalfa was grown in a warm greenhouse section with a minimum daytime temperature of 25 °C and 19 °C at night and the other half in a cool section with a daytime minimum of 15 °C and 9 °C at night. Although shoot yields were higher under warm than under cool conditions, yield response to phosphorus was greater under cool than warm growing conditions. Yield increases due to phosphorus were linear under optimum and wet soil moisture regimes and nonsignificant under the semi-dry regime. Phosphorus application increased root weight by 18% under the cool regime compared to 14% in the warm greenhouse. Phosphorus uptake by alfalfa increased with increasing rates of soil-applied P, except in semi-dry soils at warm temperature, where no effect of P on P uptake was recorded. Phosphorus uptake increased significantly with soil pH and was higher under warm temperature and optimal water regime.Key words: Phosphorus fertilization, available phosphorus, alfalfa, soil moisture regime, air temperature, phosphorus uptake

Field performance of potato (Solanum spp.) cuttings in the warm tropics: Influence of planting system, hilling, density and pruning

Growing potatoes from cuttings for seed and table potato production has great potential in Asia. There is limited information available explaining the agronomic methodology of growing cuttings in the field. This research was conducted to assess the importance of 4 management variables on the growth and tuber yield of cuttings. Three planting systems were evaluated with and without hilling. Only hilling significantly improved yields and increased tuber number per plant by 50%. Hilling also reduced tuber greening. Increasing plant population from 40,000 to 100,000 per hectare resulted in a yield increase of at least 50%, however average tuber size decreased. Pruning of the apical shoot at or after transplanting did not improve branching, canopy cover or tuber yield. Yields from cuttings were equal to or greater than the tuber seed grown control treatments. Yields ranged from 15 to 20 t/ha which is acceptable for the warm growing conditions. These results show the potential of using cuttings in commercial growing of potatoes in the warm tropics where tuber seed is difficult to obtain and maintain.

Time course of photosynthetic temperature acclimation in Carex eleocharis Bailey

Abstract Photosynthetic temperature acclimation in Carex eleocharis has been demonstrated in a previous study in which warm grown (35/15°C) plants were shown to have photosynthetic temperature optima approximately 14°C higher than cool grown (20/15°C) plants (Monson, Littlejohn & Williams, 1983). The current study examined the time course of this acclimation by determining photo‐synthetic temperature optima as a function of time, of cool grown plants moved to warm growing conditions. Leaves which had developed under cool conditions were capable of an upward adjustment of 6–8°C of their optimum photosynthetic temperature within a time span of 6–14 d. For greatest photosynthetic temperature acclimation it was necessary for leaves to form and develop entirely under warm conditions. These leaves exhibited a 14–15°C upward adjustment of their optimum temperature for photosynthesis within 20–31 d since moving plants from cool to warm growing conditions. Thus, the time course of this acclimation is of short enough duration to be significant during the growing season and presumably contributes toward the ability of this species to maintain active growth during the cool and warm portions of the growing season. It is also noted that the plant with its capacity to form new leaves, has a much wider acclimation capacity than any single leaf.

Cool Temperature Induction of Brown Center in ‘Russet Burbank’ Potatoes1

Abstract A study was conducted to determine if subjecting potato plants (Solanum tuberosum L. cv. Russet Burbank) to cool growing temperatures during and shortly after tuber formation would induce the development of brown center or hollow heart. Plants were moved at weekly intervals following tuber initiation from warm growing conditions into a 3-week cool environment (10° nights/18°C days). Plants were then returned to warm conditions (18° nights/23° days) for a period of several weeks and harvested. Those plants given the 3-week cool treatment or grown continuously in the cool after tuber initiation showed a significantly higher incidence of brown center.

Kenaf Versus Forests as a Source of Paper Pulp

SUMMARY Kenaf (Hibiscus cannabinus L.), an herbaceous annual, is a potential source of raw material for the pulp industry. It is adapted to warm growing conditions and is capable of high productivity. Pulping tests have shown that the bark and wood fractions of the stem can be pulped by conventional processes to give pulps comparable with commercial wood pulps. The seed and the leaves could also be valuable by-products. A preliminary appraisal of its potential is made on the basis of field trials conducted at Kimberley Research Station in the Ord Irrigation Area. Comparisons are made with forests in relation to productivity, production economics, land resources and environmental impact. It is concluded that there are reasonable prospects of kenaf being grown profitably under irrigation in northern Australia if it could be sold at the present U.S.A. f.o.b. price for woodchips. However, profitable production would require utilisation of the leaves and seed.