BIOMASS AND CHEMICAL RESPONSES OF Desmanthus spp. ACCESSIONS SUBMITTED TO WATER DEPRIVATION1

ABSTRACT Due to the predictions of climate change, there is a need to identify forage plants that can keep their productivity and nutritive value under hydric stress. The objective of this study was to evaluate the biomass and chemical responses of three Desmanthus spp. accessions under two water deprivation regimens (7 and 21-day). The experimental design used was randomized blocks in a 3 × 2 factorial arrangement (access and water deprivation) with four replications. There were reductions in the biomasses of leaf and stem fractions of 64% and 51%, respectively. The 43F accession showed greater leaf (1.86 g.plant-1) and stem (1.97 g.plant-1) biomasses under a total water restriction of 21 days, compared to the 89F and AusT accessions. In accessions 43F and 89F, there were carbohydrate accumulations in the leaves of 28% and 51%, respectively, under the 21-day water restriction, while AusT decreased 38% within a 7-day interval. Water deprivation affected the chemical characteristics of the accessions. Free proline was similar among accessions and accumulated 463% more in the leaves of plants submitted to 21-day water deprivation (90.22 mg.kg-1) compared to those subjected to water deprivation for 7 days (16.03 mg.kg-1). Proline and total soluble carbohydrate accumulation in 43F and 89F were insufficient to regulate crude protein, C content, and C:N ratios. These results demonstrate the variability in drought tolerance among accessions. Accessions 43F and 89F were more susceptible to 21-day water deprivation, while AusT showed greater drought tolerance.

Physiological and biochemical responses of argan (Argania spinosa (L.)) seedlings from containers of different depths under water stress

Plant species characteristic of arid and semi-arid zones, such as Argania spinosa (L.) Skeels, have a taproot that allows them to reach the soil horizons more quickly. Unfortunately, in the nursery, the containers of culture used for the production of seedlings do not support an excellent development of the root architecture that can be able to resist the shock of transplantation, in particular of the hydric stress. This study aimed to evaluate the physiological and biochemical behavior of Argania spinosa seedlings grown in containers of different depths under water stress. An experiment was conducted with 90 seedlings from the different containers (P1 for depth of 16 cm, P2 for depth of 30 cm, and P3 for depth of 60 cm), and three watering treatments (well-watered 100% of field capacity, moderate stress with 50% of field capacity and severe stress with 25% of the field capacity). Our results showed that seedlings from the 16 cm container had lower values of water status. Malondialdehyde content, electrolyte leakage, hydrogen peroxide, and superoxide radical content gave higher values on seedlings from the shallow container. The benefits of increasing the container depth of nursery seedlings contribute to the improvement of physiological and biochemical responses of seedlings under water stress. To fully validate our findings, a long-term field study must be conducted.

Identification of Sorghum (Sorghum bicolor (L.) Moench) Genotypes with Potential for Hydric and Heat Stress Tolerance in Northeastern Mexico

Sorghum (Sorghum bicolor (L.) Moench) is cultivated in regions with frequent drought periods and high temperatures, conditions that have intensified in the last decades. One of the most important photosynthetic components, sensible to hydric stress, is maximum quantum yield for photosystem II (PSII, or Fv/Fm). The objective of the present study was to identify sorghum genotypes with tolerance to hydric and heat stress. The treatments were hydric status (hydric stress or non-hydric stress (irrigation)), the plant’s developmental stages (pre or post-anthesis), and six genotypes. The response variables were Fv/Fm; photosynthetic rate (PN); stomatal conductance (gs); transpiration rate (E); relative water content (RWC); damage to cell membrane (DCM) at temperatures of 40 and 45 °C; and agronomic variables. The experiment was conducted in pots in open sky in Marín, N.L., in the dry and hot northeast Mexico. The treatment design was a split–split plot design, with three factors. Hydric stress diminished the functioning of the photosynthetic apparatus by 63%, due to damage caused to PSII. Pre-anthesis was the most vulnerable stage to hydric stress as it decreased the weight of grains per panicle (85%), number of grains per panicle (69%), and weight of 100 grains (46%). Genotypes LER 1 and LER 2 were identified as tolerant to hydric stress, as they had lower damage to PSII; LER 1 and LEB 2 for their superior RWC; and LER 1 as a thermo tolerant genotype, due to its lower DCM at 45 °C. It was concluded that LER 1 could have the potential for both hydric and heat stress tolerance in the arid northeast Mexico.

Influence of Water Stress on Growth, Chlorophyll Contents and Solute Accumulation in Three Accessions of Vicia faba L. from Tunisian Arid Region

In this study, we aim to investigate the physiological and biochemical adaptations of Vicia faba plants to moderate irrigation regime (T1) and describe the effects of water stress on their growth performance and chlorophyll contents. For this reason, three Tunisia accessions (ElHamma, Mareth and Medenine) were studied. An experiment was conducted for one month. Faba bean plants were first grown in a greenhouse and then, exposed to water stress, whereby they were irrigated up to the field capacity (FC) of 0% (control, T0) and 50% of the control (moderate stress, T1). The effect of water stress on physiological parameters showed differences in relation to the accessions studied and the water regime. Relative water content (RWC) of ElHamma accession does not seem to be affected by stress as compared with the control regime. Total chlorophyll content decreases, whereas soluble sugar contents increases for all accessions studied. ElHamma has the highest content. About morphological parameters, bean growth varies according to the ascension and treatment. Hydric stress impedes the growth of the root part and caused a significant reduction in the shoot and root Dry Weight (DW) of the T1-stressed beans, compared to the optimal irrigation (T0).

One Hundred Candidate Genes and Their Roles in Drought and Salt Tolerance in Wheat

Drought and salinity are major constraints to agriculture. In this review, we present an overview of the global situation and the consequences of drought and salt stress connected to climatic changes. We provide a list of possible genetic resources as sources of resistance or tolerant traits, together with the previous studies that focused on transferring genes from the germplasm to cultivated varieties. We explained the morphological and physiological aspects connected to hydric stresses, described the mechanisms that induce tolerance, and discussed the results of the main studies. Finally, we described more than 100 genes associated with tolerance to hydric stresses in the Triticeae. These were divided in agreement with their main function into osmotic adjustment and ionic and redox homeostasis. The understanding of a given gene function and expression pattern according to hydric stress is particularly important for the efficient selection of new tolerant genotypes in classical breeding. For this reason, the current review provides a crucial reference for future studies on the mechanism involved in hydric stress tolerance and the use of these genes in mark assistance selection (MAS) to select the wheat germplasm to face the climatic changes.

PARÂMETROS PRODUTIVOS DO MILHO SOB DÉFICIT HÍDRICO EM DIFERENTES FASES FENOLÓGICAS NO SEMIÁRIDO BRASILEIRO

PARÂMETROS PRODUTIVOS DO MILHO SOB DÉFICIT HÍDRICO EM DIFERENTES FASES FENOLÓGICAS NO SEMIÁRIDO BRASILEIRO SAMUEL SILVA1, AMANDA CIBELE DA PAZ SOUSA2, CARLA SABRINA DA SILVA3, EDMAÍRIS RODRIGUES ARAÚJO4, MARCELO AUGUSTO DA SILVA SOARES5, IÊDO TEODORO6 1Professor do Instituto Federal de Alagoas (IFAL), Campus Piranhas, Av. Sergipe, 1477, 57460-000, Piranhas, Alagoas, Brasil, [email protected] 2 Graduanda em Engenharia Agronômica, Instituto Federal de Alagoas (IFAL), Campus Piranhas, Av. Sergipe, 1477, 57460-000, Piranhas, Alagoas, Brasil, 8° período. E-mail: [email protected] 3 Graduanda em Engenharia Agronômica, Instituto Federal de Alagoas (IFAL), Campus Piranhas, Av. Sergipe, 1477, 57460-000, Piranhas, Alagoas, Brasil, 5° período. E-mail: [email protected] 4 Graduanda em Engenharia Agronômica, Instituto Federal de Alagoas (IFAL), Campus Piranhas, Av. Sergipe, 1477, 57460-000, Piranhas, Alagoas, Brasil, 5° período. E-mail: [email protected] 5 Doutorando em Produção Vegetal, Departamento de Tecnologia da Produção, Universidade Federal de Alagoas (UFAL), Av. Lourival Melo Mota, S/N, Tabuleiro do Martins, 57072-970, Maceió, Alagoas, Brasil, [email protected]. 6 Professor do Centro de Engenharia e Ciências Agrárias (CECA), Universidade Federal de Alagoas (UFAL), Av. Lourival Melo Mota, S/N, Tabuleiro do Martins, 57072-970, Maceió, Alagoas, Brasil, [email protected]. 1 RESUMO O objetivo deste trabalho foi avaliar o efeito do déficit hídrico em diferentes fases fenológicas do milho na região semiárida de Alagoas. O experimento foi conduzido no Instituto Federal de Alagoas, Campus Piranhas, durante os meses de fevereiro a junho de 2019. A partir dos dados coletados nas plantas durante a condução do experimento, foram realizadas as seguintes etapas: análise do efeito dos elementos climáticos sobre a cultura, determinação da produtividade em cada tratamento, avaliação de variáveis da espiga sob o efeito do déficit hídrico e estimativa da evapotranspiração da cultura (ETc). As plantas submetidas ao déficit hídrico nas fases de pendoamento e floração sofreram variação no número de grão por espiga e tiveram baixa produtividade quando comparadas às plantas submetidas na fase de grão farináceo. A temperatura e umidade do ar não influenciaram na limitação térmica para o desenvolvimento do milho durante todo o ciclo. Plantas submetidas ao déficit hídrico na fase de pendoamento e floração foram menos produtivas. Palavras-chave: umidade do solo, estresse hídrico, produtividade agrícola. SILVA, S., SOUSA, A. C. P; SILVA, C. S.; ARAÚJO, E. R.; SOARES, M. A. S.; TEODORO, I. PRODUCTIVE PARAMETERS OF MAIZE UNDER WATER DEFICIT IN DIFFERENT PHENOLOGICAL PHASES IN THE BRAZILIAN SEMI-ARID 2 ABSTRACT The objective of this work was to evaluate the effect of water deficit in different phenological phases of maize in the semiarid region of Alagoas, Brazil. The experiment was conducted at the Federal Institute of Alagoas, Campus Piranhas, from February to June 2019. From the data collected from the plants during the conduct of the experiment, the following steps were performed: analysis of the effect of climatic elements on the crop, determination of productivity in each treatment, evaluation of growth data and ear variables under the effect of the deficit water, estimation of crop evapotranspiration (ETc) and verification of the level of impact of water stress caused in each phonological phase of the culture. The plants subjected to water deficit in the tasseling and flowering phases suffered variation in the number of grains per ear and had low yield compared to the plants submitted to the farinaceous grain phase. The evapotranspiration of the crop, temperature and humidity did not influence the thermal limitation for developing maize throughout the cycle. Plants submitted to water deficit during the planting and flowering phase were less productive. Keywords: soil moisture, hydric stress, yield.

Effect of Quercetin on Mycorrhizal Synthesis between Tuberborchii and Arbutusunedo L. In Vitro Plants

Arbutus unedo L. is a Mediterranean species used for fruit production; it is tolerant to drought and shows regeneration ability following forest fires. Mycorrhizal plants with Tuber borchii add resilience and value. This study aims to test the effect of quercetin on mycorrhizal synthesis between T. borchii and A. unedo. Two genotypes selected for fruit production and hydric stress tolerance, were micropropagated for mycorrhizal synthesis, accomplished during ex vitro rooting in perlite, using lyophilized spores of T. borchii suspended in culture media with different quercetin levels (0–10 µM). Six months after inoculation, plants were transferred to pots and maintained in nursery. Ten and 12 months after inoculation, roots were morphological examined and molecularly characterized using ITS1-5.8SITS2 rDNA region and specific primers. Results showed that mycorrhizae establishment was dependent on studied factors (genotype, quercetin level, and culture medium) and their interaction (genotype X culture medium). Quercetin levels up to 2.0 µM favored mycorrhizae establishment and plant growth, although levels superior to 4 µM showed a toxic effect. Quercetin showed to be an efficient factor on inducing mycorrhiza thriving independent of the genotype. Morphological observations and molecular analysis confirmed the permanence of the fungus association 10 and 12 months after inoculation.