Doctor of Philosophy / Rice (Oryza sativa L.) is very susceptible to water deficit at any time during its life cycle as a semi-aquatic cereal crop. However, the consequential damage is particularly severe if water deficit occurs during reproductive phases. The conspicuous injury often observed in rice plants exposed to water stress during meiosis of the pollen mother cell is the reduction of grain set, which is attributed to the decline of male fertility. In spite of much research on drought-induced male sterility in rice, the underlying mechanisms of the problem are poorly understood. This project was therefore conducted to investigate the molecular mechanisms of water deficit-induced pollen sterility in rice. In this study three consecutive days of water deficit treatment at -0.5 MPa osmotic potential during anther development effectively reduced the leaf water potential (leaf) and the number of viable pollen which later led to a decrease in grain set. Moreover, this thesis demonstrates that the immediate deleterious effects of water deficit to plant fertility could be estimated using a young microspore viability index, which showed a strong correlation with mature viable pollen and grain set. The present work has also illustrated that oxidative stress appears to be a plausible cause for the decline of male fertility and grain set. Water deficit has induced the excessive production of reactive oxygen species (ROS) above the redox balance, which in turn caused detrimental effects to cellular DNA and might result in programmed cell death (PCD) in the anthers. Moreover, ROS accumulation effectively influenced ATP synthesis leading to a decrease in the level of ATP in the anthers. Excessive ROS accumulation after drought could be the consequence of insufficient activity of the antioxidant system, which has been illustrated by qRT-PCR expression analysis of major antioxidant genes. Down-regulation of those genes would increase the incidence of oxidative damage. In contrast, stable or up-regulated expression of these genes resulted in less oxidative damage. Detailed investigations of sugar metabolism in anthers has provided supplemental data to develop a model of sugar unloading and transport within anther using in situ hybridisation to mRNA techniques. Analysis of sugar transportation within the cellular compartments of anther has unveiled the role of sugar metabolism on pollen sterility in rice. qRT-PCR assays of genes associated with the sugar metabolic pathway has demonstrated that the supply of both sucrose and hexoses from the anther walls to the locules was not restricted after water deficit stress. The results indicate that water deficit might not cause sugar starvation for developing microspores as previously thought, nor inhibit the initial steps of sugar utilisation such as glycolysis. This thesis has suggested new ideas regarding the role of rising sugar levels to cope with oxidative stress in anthers. Sugar accumulation might have provided protection against oxidant damage by strengthening the antioxidant system. However, the interplay between sugar and oxidative stress is not straightforward and needs to be further characterised. In-depth investigations on the interaction between sugar signalling and oxidative stress responses may help indentify the role of sugars in protecting anthers under water deficit. Although many studies on drought and chilling stresses in rice anthers have been performed, the causal mechanism of male sterility still remains to be elucidated. Findings presented in this thesis may contribute to understanding molecular mechanisms of male sterility in rice as a response to drought stress. A more detailed investigation of mitochondrial respiration in rice anthers is required to further examine this problem. Finally, this thesis suggests that signalling molecules such as 14-3-3 proteins and abscisic acid (ABA) might act upstream of ROS production and antioxidant defence in plants. Further work on these molecules might therefore further illustrate how they influence plant fertility under water shortage conditions.

The Australian wheat production environments are typically water-limited, and both temperature and vapour pressure deficit increase as the season progresses. As a result, high incidences of small or shriveled wheat kernels (screenings) are commonly generated and can substantially reduce grain value. Previous studies suggest the incorporation of the tiller inhibition (tin) gene can reduce the production of infertile tillers and increase kernel weight (KW). It was hypothesised that the incorporation of the tin gene into wheat germplasm may a) contribute to the maintenance of large KW and reduction in screenings (SCR) in terminal water deficit environments; and b) not be associated with a grain yield (GY) penalty in terminal water deficit environments. Thus, the major objective of this thesis was to evaluate the expression and performance of tin gene in terms of GY and SCR: 1) in different genetic backgrounds and across Australian production environments; 2) in various northern production environments which are particularly prone to terminal water deficit conditions; and 3) to determine the mechanisms that contribute to the maintenance of large KW of tin lines in terminal stress conditions. To address the overall objective, populations of lines were genotyped for the presence/absence of the tin gene and were field tested. Line differences in GY, yield components, SCR and general growth and development attributes were determined in 22 field experiments conducted between 2005-2007. The experiments were grouped into those that evaluated: a large number of sister lines from four genetic backgrounds in multi-location experiments; selected lines from Silverstar population in multi-location experiments; and selected sister lines in detailed agronomic experiments examining the effect of plant density and controlled levels of water supply through the use of a rainout shelter facility. The effect of tin on GY and SCR varied with environment and genetic background. In the Brookton, Wyalkatchem and Chara background, there was no reduction in GY associated with tin in southern production environments. However, a 31% and 10%, advantage of free-tillering over reduced tillering Silverstar lines existed in the 2005 western and 2006 northern experiments respectively, and led to an average 12% reduction in GY of Silverstar tin lines. In northern experiments, tin lines in a Silverstar background produced up to 50% fewer SCR than Silverstar free-tillering lines. Averaged across experiments, KW of Silverstar tin lines was 10% greater than free-tillering lines. Based on stem number per plant, Silverstar lines were classified into three groups; the restricted (R) and semi-restricted (SR) tin and free-tillering lines attained 2.9, 3.4 and 4.8 stems per plant respectively. Expression of tin in terms of maximum stem number production was genetic background and genotype dependent, and unlike free-tillering lines, R tin lines in particular, were not as responsive to plant density. Head number per unit area rather than kernel number per head was strongly associated with KW determination. Therefore, to maximize KW under water limiting conditions it is more beneficial if high kernel number can be achieved via the production of low head number with more kernels per head, as can be achieved with the use of tin lines. The KW advantage of Silverstar R tin was associated with greater anthesis total dry matter, stem water soluble carbohydrate and nitrogen available per head relative to free-tillering lines, and thus R tin lines had more assimilate for translocation during the grain filling period. In a terminal water deficit experiment, individual KW data collected for Silverstar tin and free-tillering lines revealed that KW of tin lines (≈ 25 mg per kernel) was maintained for main stem to fourth tiller heads and across floret positions 1-4 within spikelets. In contrast, free-tillering lines (≈ 18 mg per kernel) generated small kernels across the entire plant, with the largest proportion originating from floret positions 3 and 4. Lines containing the tin gene had a greater mean KW and kernel width, and a higher frequency of wider kernels than free-tillering lines. The high frequency of large kernel widths was associated with significantly less SCR in tin lines. A strong positive association between maturity head number per plant and SCR indicated, for every fertile head produced, SCR increased by 11% in the terminal water deficit experiment. Reduction in SCR in the Silverstar tin material in the north, was associated with high KW and a tendency for lower GY, although tin lines with equivalent GY to Silverstar could be identified in each environment. The incorporation of the tin gene has the potential to significantly reduce the incidence of SCR in commercial wheat crops. The reduction in GY associated with the tin gene was dependent on genetic background, suggesting the potential for selection of higher-yielding tin progeny in commercial line development. However, a tailored agronomic package to optimize yield potential of tin lines needs to be developed for different target environments. With the incorporation of the tin gene into genetic material adapted to the northern wheat belt and optimisation of head density, there exists scope for simultaneous improvements in GY and KW and subsequent reduction in SCR for terminal water deficit environments.

An autonomous machine vision guided plant sensing and monitoring system was designed and constructed to continuously monitor plant related features: color (red-green-blue, hue-saturation-luminance, and color brightness), morphology (top projected canopy area), textural (entropy, energy, contrast, and homogeneity), Normalized Difference Vegetative Index (NDVI) (as well as other similar indices from the color and NIR channels), and thermal (plant and canopy temperature). Several experiments with repeated water stress cycles, using the machine vision system, was conducted to evaluate the machine vision system's performance to determine the timeliness of induced plant water stress detection. The study aimed at identifying significant features separating the control and treatment from an induced water stress experiment and also identifying, amongst the plant canopy, the location of the emerging water stress with the found significant features. Plant cell severity had been ranked based on the cell's accumulated feature count and converted to a color coded graphical canopy image for the remote operator to evaluate. The overall feature analysis showed that the morphological feature, Top Projected Canopy Area, was found to be a good marker for the initial growth period while the vegetation indices (ENDVI, NDVIBlue, and NDVIRed) were more capable at capturing the repeated stress occurrences during the various stages of the lettuce crop. Furthermore, the crop's canopy temperature was shown to be a significant and dominant marker to timely detect the water stress occurrences. The graphical display for the remote user showed the severity of summed features to equal the detection of the human vision. Capabilities and limitations of the developed system and stress detection methodology were documented with recommendations for future improvements for the crop monitoring/production system. An example web based decision support platform was created for data collection, storage, analysis, and display of the data/imagery collected for a remote operator.

This thesis studied the influence of moisture content on the dynamic estimation of stiffness in wood of Pinus radiata D. Don. This is an important non-destructive measure for estimation of stiffness in standing trees, logs and lumber. Moisture content affects both acoustic velocity and density in the fundamental equation of dynamic MOE (DMOE = V²ρ, where V = acoustic velocity and ρ = density). Investigation included measurements with boards in the laboratory considering moisture contents below and above FSP as well as temperatures below and above 0°C. This also included field measurements of trees in contrasting climate sites and over different seasons including a long drought. Methods for measuring green density and moisture content and the patterns of variation of these parameters were also investigated. A secondary component of this thesis explored the wood quality and some mechanisms of tree response to water stress in two contrasting sites in terms or rainfall and water deficits in a region of Australia. The large increases in DMOE for frozen wood above the FSP (4.5 to 6 GPa) will limit the use of DMOE for grading logs in regions with freezing winters. Results from the experiment remeasuring young trees and the upper range of moisture content and temperatures above 0°C from the experiment with boards showed small to moderate variation in DMOE (0.1 to 1 GPa) which calls for further investigation on analytical procedures for adjustment of DMOE. Such procedures should consider that variations in acoustic velocity and density with changes in moisture content are not proportional and that there are counteracting effects between the two parameters. It remains to be investigated whether the typical variation (under normal climate conditions) in sapwood green density observed in our experiments has some implications for the use of DMOE. On the other hand, it is anticipated that the large differences along the stem and among stands in whole-section green density may bias DMOE measurements in logs for resource assessment. This also needs to be investigated. A comparison between acoustic velocity alone and DMOE for resource assessment under different scenarios is recommended. The study in two contrasting climate sites (high-altitude vs. warm-dry) in the Hume region of Forests NSW, Australia, including young (10-11 years) and mature trees (34 36 years) of radiata pine showed distinctive short and long-term responses of trees to cope with the water-limiting environment. In response to long-term water deficits the warm-dry site developed heartwood and thus reduced sapwood earlier and at faster rates than the high-altitude site. The onset of heartwood formation seemed to be triggered by some site threshold for water use as broadly indicated by the sapwood area/ha. The latter was consistently lower for the warm-dry site across the different stands. The warm-dry site also showed increased short-term responses to water stress and these were interpreted as seasonal mechanisms of the trees to cope with the limiting environment. The trees compensated for the lower available moisture and higher transpiration rates by lowering their saturation and disrupting water conduction at some points (cavitation). The inverse trends of cavitation spots and cavitation bands with height in the stem suggested the trees have different strategies to sacrifice conducting xylem depending on the position on the stem. Finally, it is suggested that saturation tended to fall to critical 'safe' levels as a result of water stress and this varied depending on age, site, and position in the stem. Significant decreases in DMOE and basic density were observed for the warm-dry site and were attributed to lower proportions of latewood due to lower rainfall for that site during the period of latewood formation. These showed no obvious association with any of the long-term water-stress traits (sapwood percentage and number of heartwood rings).

Hydraulic conductance of roots of the grapevine cultivar, Chardonnay, varies diurnally, peaking at 1400 h. The diurnal amplitude of hydraulic conductance between 600 and 1400 h was not altered when potted grapevines were water-stressed by withholding water for 8 days. However, the diurnal change was greatly reduced for water-stressed Grenache. If the diurnal change in root hydraulic conductance is a result of changes in aquaporin gene expression or activity, it suggests that aquaporins respond differently in water-stressed Chardonnay and Grenache roots. Both Chardonnay and Grenache demonstrated a reduction in hydraulic conductance in response to water stress, with Grenache exhibiting a larger reduction. Suberisation of the roots increased in response to water stress, with complete suberisation of the endodermis occurring closer to the root tip of Grenache compared to the more drought sensitive Chardonnay. The drought sensitive rootstock, 101-14 (V. riparia × V. rupestris) demonstrated a similar reduction in hydraulic conductance to Chardonnay, while drought tolerant 1103 Paulsen (V. berlandieri × V. rupestris) had a non-significant reduction when water-stressed compared to the large reduction observed for drought tolerant Grenache. Therefore, in this study the degree of reduction in hydraulic conductance did not relate to the drought tolerance of the four varieties examined. The impact of partial drying (watering only half the root system) on hydraulic conductance also differed between Chardonnay and Grenache. There was no change in the conductance of the whole root system of Chardonnay due to an increase in conductance of the roots in the wet half which compensated for the reduction on the dry side. In contrast, Grenache did suffer a reduction measured over the whole root system due to a much larger reduction on the dry side compared to Chardonnay. There was an increase in hydraulic conductance on the wet side but this could not compensate for the large reduction on the dry side. Two aquaporins (VvPIP1;1 and VvPIP2;2) were cloned from the roots of grapevine cultivar Chardonnay. The genes were expressed in Xenopus oocytes to determine their osmotic permeability. As has been shown in a number of plant species, VvPIP1;1 was only slightly permeable to water, whereas VvPIP2;2 did transport water. However, when VvPIP1;1 was injected into the oocytes with VvPIP2;2, there was a substantial increase in the osmotic permeability. There was no significant variation in the diurnal expression of VvPIP2;2, whereas VvPIP1;1 showed a peak in expression at 1000 h prior to the peak in hydraulic conductance and peaked again at 1800 h. VvPIP2;2 did not vary in transcript level in response to water stress or rewatering in Chardonnay or Grenache roots. The level of VvPIP1;1 doubled in water stressed Chardonnay roots and declined again when the vines were rewatered 24 h previously. This response to water stress did not occur in Grenache roots. The roots used were from the apical 5 cm. Similar roots were used to measure the water permeability of the cortical cell membranes using the cell pressure probe. Changes in cell membrane permeability in response to water stress corresponded to changes in VvPIP1;1 expression. An experiment to determine if shoot topping had an effect on root hydraulic conductance revealed a significant 50% decline. This response was also observed in soybean (Glycine max L.) and maize (Zea mays L.). A range of experiments have been performed to determine the reason for the decline. Possibilities included a response to final leaf area and reduced transpirational demand; loss of a carbohydrate sink; or hormonal signals such as abscisic acid, auxin and ethylene. At this stage the nature of the positive or negative signal that causes the change in root hydraulic conductance remains elusive. However, the signal did cause a reduction in the transcript level of VvPIP1;1, indicating the involvement of aquaporins in the response. The root hydraulic conductance of grapevines is variable and dependent on factors such as time of day, water-stress, transpiration rate and unknown signals from the shoot. A proportion of this variability is due to changes in aquaporin number or activity. There are also genotypic differences which may be beneficial for future breeding efforts to improve water use efficiency of grapevines. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1311202

Hydraulic conductance of roots of the grapevine cultivar, Chardonnay, varies diurnally, peaking at 1400 h. The diurnal amplitude of hydraulic conductance between 600 and 1400 h was not altered when potted grapevines were water-stressed by withholding water for 8 days. However, the diurnal change was greatly reduced for water-stressed Grenache. If the diurnal change in root hydraulic conductance is a result of changes in aquaporin gene expression or activity, it suggests that aquaporins respond differently in water-stressed Chardonnay and Grenache roots. Both Chardonnay and Grenache demonstrated a reduction in hydraulic conductance in response to water stress, with Grenache exhibiting a larger reduction. Suberisation of the roots increased in response to water stress, with complete suberisation of the endodermis occurring closer to the root tip of Grenache compared to the more drought sensitive Chardonnay. The drought sensitive rootstock, 101-14 (V. riparia × V. rupestris) demonstrated a similar reduction in hydraulic conductance to Chardonnay, while drought tolerant 1103 Paulsen (V. berlandieri × V. rupestris) had a non-significant reduction when water-stressed compared to the large reduction observed for drought tolerant Grenache. Therefore, in this study the degree of reduction in hydraulic conductance did not relate to the drought tolerance of the four varieties examined. The impact of partial drying (watering only half the root system) on hydraulic conductance also differed between Chardonnay and Grenache. There was no change in the conductance of the whole root system of Chardonnay due to an increase in conductance of the roots in the wet half which compensated for the reduction on the dry side. In contrast, Grenache did suffer a reduction measured over the whole root system due to a much larger reduction on the dry side compared to Chardonnay. There was an increase in hydraulic conductance on the wet side but this could not compensate for the large reduction on the dry side. Two aquaporins (VvPIP1;1 and VvPIP2;2) were cloned from the roots of grapevine cultivar Chardonnay. The genes were expressed in Xenopus oocytes to determine their osmotic permeability. As has been shown in a number of plant species, VvPIP1;1 was only slightly permeable to water, whereas VvPIP2;2 did transport water. However, when VvPIP1;1 was injected into the oocytes with VvPIP2;2, there was a substantial increase in the osmotic permeability. There was no significant variation in the diurnal expression of VvPIP2;2, whereas VvPIP1;1 showed a peak in expression at 1000 h prior to the peak in hydraulic conductance and peaked again at 1800 h. VvPIP2;2 did not vary in transcript level in response to water stress or rewatering in Chardonnay or Grenache roots. The level of VvPIP1;1 doubled in water stressed Chardonnay roots and declined again when the vines were rewatered 24 h previously. This response to water stress did not occur in Grenache roots. The roots used were from the apical 5 cm. Similar roots were used to measure the water permeability of the cortical cell membranes using the cell pressure probe. Changes in cell membrane permeability in response to water stress corresponded to changes in VvPIP1;1 expression. An experiment to determine if shoot topping had an effect on root hydraulic conductance revealed a significant 50% decline. This response was also observed in soybean (Glycine max L.) and maize (Zea mays L.). A range of experiments have been performed to determine the reason for the decline. Possibilities included a response to final leaf area and reduced transpirational demand; loss of a carbohydrate sink; or hormonal signals such as abscisic acid, auxin and ethylene. At this stage the nature of the positive or negative signal that causes the change in root hydraulic conductance remains elusive. However, the signal did cause a reduction in the transcript level of VvPIP1;1, indicating the involvement of aquaporins in the response. The root hydraulic conductance of grapevines is variable and dependent on factors such as time of day, water-stress, transpiration rate and unknown signals from the shoot. A proportion of this variability is due to changes in aquaporin number or activity. There are also genotypic differences which may be beneficial for future breeding efforts to improve water use efficiency of grapevines. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1311202

Doctor of Philosophy / Rice (Oryza sativa L.) is very susceptible to water deficit at any time during its life cycle as a semi-aquatic cereal crop. However, the consequential damage is particularly severe if water deficit occurs during reproductive phases. The conspicuous injury often observed in rice plants exposed to water stress during meiosis of the pollen mother cell is the reduction of grain set, which is attributed to the decline of male fertility. In spite of much research on drought-induced male sterility in rice, the underlying mechanisms of the problem are poorly understood. This project was therefore conducted to investigate the molecular mechanisms of water deficit-induced pollen sterility in rice. In this study three consecutive days of water deficit treatment at -0.5 MPa osmotic potential during anther development effectively reduced the leaf water potential (leaf) and the number of viable pollen which later led to a decrease in grain set. Moreover, this thesis demonstrates that the immediate deleterious effects of water deficit to plant fertility could be estimated using a young microspore viability index, which showed a strong correlation with mature viable pollen and grain set. The present work has also illustrated that oxidative stress appears to be a plausible cause for the decline of male fertility and grain set. Water deficit has induced the excessive production of reactive oxygen species (ROS) above the redox balance, which in turn caused detrimental effects to cellular DNA and might result in programmed cell death (PCD) in the anthers. Moreover, ROS accumulation effectively influenced ATP synthesis leading to a decrease in the level of ATP in the anthers. Excessive ROS accumulation after drought could be the consequence of insufficient activity of the antioxidant system, which has been illustrated by qRT-PCR expression analysis of major antioxidant genes. Down-regulation of those genes would increase the incidence of oxidative damage. In contrast, stable or up-regulated expression of these genes resulted in less oxidative damage. Detailed investigations of sugar metabolism in anthers has provided supplemental data to develop a model of sugar unloading and transport within anther using in situ hybridisation to mRNA techniques. Analysis of sugar transportation within the cellular compartments of anther has unveiled the role of sugar metabolism on pollen sterility in rice. qRT-PCR assays of genes associated with the sugar metabolic pathway has demonstrated that the supply of both sucrose and hexoses from the anther walls to the locules was not restricted after water deficit stress. The results indicate that water deficit might not cause sugar starvation for developing microspores as previously thought, nor inhibit the initial steps of sugar utilisation such as glycolysis. This thesis has suggested new ideas regarding the role of rising sugar levels to cope with oxidative stress in anthers. Sugar accumulation might have provided protection against oxidant damage by strengthening the antioxidant system. However, the interplay between sugar and oxidative stress is not straightforward and needs to be further characterised. In-depth investigations on the interaction between sugar signalling and oxidative stress responses may help indentify the role of sugars in protecting anthers under water deficit. Although many studies on drought and chilling stresses in rice anthers have been performed, the causal mechanism of male sterility still remains to be elucidated. Findings presented in this thesis may contribute to understanding molecular mechanisms of male sterility in rice as a response to drought stress. A more detailed investigation of mitochondrial respiration in rice anthers is required to further examine this problem. Finally, this thesis suggests that signalling molecules such as 14-3-3 proteins and abscisic acid (ABA) might act upstream of ROS production and antioxidant defence in plants. Further work on these molecules might therefore further illustrate how they influence plant fertility under water shortage conditions.

Made available in DSpace on 2016-08-12T19:15:37Z (GMT). No. of bitstreams: 1 JoseGOS_DISSERT.pdf: 750943 bytes, checksum: a7db17eb67ceb1187e14a357b382b729 (MD5) Previous issue date: 2016-02-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The introduction of exotic species in natural communities is usually mediated by human activity. One example is Cryptostegia madagascariensis, species considered invasive in almost every country in which it was introduced. In Brazil, it is invading wetlands in the Northeast and is known as the Carnaubeiras (Copernicia prunifera) killer. The species is highly tolerant to flooding, but it also has drought tolerance. It is necessary to understand how adaptation to drought occurs, to identify the capacity of this plant to invade new areas. The objective of this work is to understand the adaptation of C. madagascariensis to low water availability. This study was conducted in the seedling nursery of the Department of Plant Sciences at the Federal Rural University of the Semi-Arid (UFERSA). It was adopted a randomized blocks design in subdivided plots, with four blocks. In the plots, the water treatments were placed (irrigated and stressed). The subplots were the plant sages (4, 6 and 8 months). When the plants showed leaf senescence, irrigation was resumed and leaves were selected for biochemical analyzes of photosynthetic pigments, total soluble sugars and total free amino acids were made. At 5 days of water deprivation, the plants had reduced photosynthesis, stomatal conductance and transpiration. At that point, there was a statistical difference for the water potential at noon, pre-dawn, free amino acids and soluble sugars in plants that were subjected to stress. The behavior exhibited by Cryptostegia madagascariensis indicates that this species has a conservative profile, reducing their leaf area and promoting stomatal closure to conserve water / A introdução de espécies exóticas em comunidades naturais é, geralmente, mediada pela atividade humana. Um exemplo disso é a Cryptostegia madagascariensis, que se tornou invasora em quase todos os países nos quais foi introduzida. No Brasil, está invadindo áreas alagáveis do Nordeste, sendo conhecida como assassina das carnaubeiras (Copernicia prunifera). A espécie é altamente tolerante ao alagamento, mas também tem tolerância à seca. É necessário entender como ocorre a adaptação à seca para identificar a capacidade dessa planta para invadir novas áreas. Assim, o objetivo desse trabalho foi compreender a adaptação de C. madagascariensis a condições de baixa disponibilidade de água. O presente estudo foi conduzido em viveiro de mudas no delineamento em blocos casualizados no esquema de parcelas subdivididas, com quatro blocos. Nas parcelas, foram avaliados os regimes hídricos (irrigadas e estressadas) e as idades (4, 6 e 8 meses). Quando as plantas apresentaram senescência foliar, foi retomada a irrigação e selecionadas as folhas para serem feitas as análises bioquímicas. Foram feitas as análises de pigmentos fotossintéticos, açúcares solúveis totais e aminoácidos livres totais. Com cinco dias de estresse, as plantas apresentaram redução da fotossíntese, condutância estomática e transpiração. Nesse ponto, houve diferença estatística para o potencial hídrico ao meio dia, no pre-dawn, aminoácidos livres e açúcares solúveis nas plantas que foram submetidas ao estresse. O comportamento apresentado pela Cryptostegia madagascariensis indica que a espécie possui um perfil conservador, reduzindo sua área foliar e promovendo o fechamento estomático para conservar água no seu interior

Made available in DSpace on 2016-08-12T19:18:54Z (GMT). No. of bitstreams: 1 JoseGOS_DISSERT.pdf: 750943 bytes, checksum: a7db17eb67ceb1187e14a357b382b729 (MD5) Previous issue date: 2016-02-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The introduction of exotic species in natural communities is usually mediated by human activity. One example is Cryptostegia madagascariensis, species considered invasive in almost every country in which it was introduced. In Brazil, it is invading wetlands in the Northeast and is known as the Carnaubeiras (Copernicia prunifera) killer. The species is highly tolerant to flooding, but it also has drought tolerance. It is necessary to understand how adaptation to drought occurs, to identify the capacity of this plant to invade new areas. The objective of this work is to understand the adaptation of C. madagascariensis to low water availability. This study was conducted in the seedling nursery of the Department of Plant Sciences at the Federal Rural University of the Semi-Arid (UFERSA). It was adopted a randomized blocks design in subdivided plots, with four blocks. In the plots, the water treatments were placed (irrigated and stressed). The subplots were the plant sages (4, 6 and 8 months). When the plants showed leaf senescence, irrigation was resumed and leaves were selected for biochemical analyzes of photosynthetic pigments, total soluble sugars and total free amino acids were made. At 5 days of water deprivation, the plants had reduced photosynthesis, stomatal conductance and transpiration. At that point, there was a statistical difference for the water potential at noon, pre-dawn, free amino acids and soluble sugars in plants that were subjected to stress. The behavior exhibited by Cryptostegia madagascariensis indicates that this species has a conservative profile, reducing their leaf area and promoting stomatal closure to conserve water / A introdução de espécies exóticas em comunidades naturais é, geralmente, mediada pela atividade humana. Um exemplo disso é a Cryptostegia madagascariensis, que se tornou invasora em quase todos os países nos quais foi introduzida. No Brasil, está invadindo áreas alagáveis do Nordeste, sendo conhecida como assassina das carnaubeiras (Copernicia prunifera). A espécie é altamente tolerante ao alagamento, mas também tem tolerância à seca. É necessário entender como ocorre a adaptação à seca para identificar a capacidade dessa planta para invadir novas áreas. Assim, o objetivo desse trabalho foi compreender a adaptação de C. madagascariensis a condições de baixa disponibilidade de água. O presente estudo foi conduzido em viveiro de mudas no delineamento em blocos casualizados no esquema de parcelas subdivididas, com quatro blocos. Nas parcelas, foram avaliados os regimes hídricos (irrigadas e estressadas) e as idades (4, 6 e 8 meses). Quando as plantas apresentaram senescência foliar, foi retomada a irrigação e selecionadas as folhas para serem feitas as análises bioquímicas. Foram feitas as análises de pigmentos fotossintéticos, açúcares solúveis totais e aminoácidos livres totais. Com cinco dias de estresse, as plantas apresentaram redução da fotossíntese, condutância estomática e transpiração. Nesse ponto, houve diferença estatística para o potencial hídrico ao meio dia, no pre-dawn, aminoácidos livres e açúcares solúveis nas plantas que foram submetidas ao estresse. O comportamento apresentado pela Cryptostegia madagascariensis indica que a espécie possui um perfil conservador, reduzindo sua área foliar e promovendo o fechamento estomático para conservar água no seu interior

The present thesis deals with evaluation of crop water stress by means of remote sensing. The first part of the research is focused on the assessment of water stress of sunflowers in a laboratory environment using spectral analysis of the reflected radiation and thermography. Leaf of suflowers temperature were evaluated and using them, the index of water stress CWSI were calculated. Reflection of leaf was evaluated in the wavelengths 350 -2500 nm. From these wavelengths spectral indexes were calculated - NDVI (Normalized difference vegetation index) which detect the presence of living green vegetation, WI (Water Index) which serve to calculate the approximate amount of water in the vegetation and RVI (simple ratio vegetation index) which determine the content of biomass or photosynthetic capacity. After that, they were compared with CWSI. Finally CWSI was compared with the spectral data, and from the resulting correlations they were apparent wavelengths, which correlated with given index more or less. The second part is focused on the assessment of water stress in terms of 4th. level catchment, specifically on catchment "Dehtáře" near Pelhřimov. There were primarily evaluated three biggest areas - fields of winter wheat, field corn and TTP.