Doctor of Philosophy / Department of Agronomy / P.V. Vara Prasad / High temperature (HT) and drought are detrimental to crop productivity, but there is limited variability for these traits among wheat ([italics]Triticum aestivum[end italics] L.) cultivars. Five [italics]Aegilops[end italics] species were screened to identify HT (52 accessions) and drought (31 accessions) tolerant species/accessions and ascertaining traits associated with tolerance. Four synthetic wheats were studied to quantify independent and combined effects of HT and drought. [italics]Aegilops[end italics] species were grown at 25/19°C day/night and 18 h photoperiod. At anthesis, HT was imposed by transferring plants to growth chambers set at 36/30°C, whereas in another experiment, drought was imposed by withholding irrigation. Synthetic wheats were grown at 21/15°C day/night and 18 h photoperiod. At anthesis or 21 d after anthesis, plants were exposed to optimum condition (irrigation + 21/15°C), HT (irrigation + 36/30°C), drought (withhold irrigation + 21/15°C), and combined stress (withhold irrigation + 36/30°C). Stresses were imposed for 16 d. High temperature and drought stress significantly decreased chlorophyll, grain number, individual grain weight, and grain yield of [italics]Aegilops[end italics] species (≥ 25%). Based on a decrease in grain yield, [italics]A. speltoides[end italics] and [italics]A. geniculata[end italics] were most tolerant (~ 61% decline), and [italics]A. longissima[end italics] was highly susceptible to HT stress (84% decline). Similarly, [italics]A. geniculata[end italics] had greater tolerance to drought (48% decline) as compared to other species (≥ 73% decline). Tolerance was associated with higher grains spike [superscript]-1 and/or heavier grains. Within [italics]A. speltoides[end italics], accession TA 2348 was most tolerant to HT with 13.5% yield decline and a heat susceptibility index (HSI) 0.23. Among [italics]A. geniculata[end italics], TA 2899 and TA 1819 were moderately tolerant to HT with an HSI 0.80. TA 10437 of [italics]A. geniculata[end italics] was the most drought tolerant accession with 7% yield decline and drought susceptibility index 0.14. Irrespective of the time of stress, HT, drought, and combined stress decreased both individual grain weight and grain yield of synthetic wheats by ≥ 37%, 26%, and 50%, respectively. These studies suggest a presence of genetic variability among [italics]Aegilops[end italics] species that can be utilized in breeding wheat for HT and drought tolerance at anthesis; and combined stress of drought and high temperature on synthetic wheats are hypo-additive in nature.

Submitted by Deyse Queiroz (deysequeirozz@hotmail.com) on 2018-05-18T15:11:35Z No. of bitstreams: 1 GLEYCE LACERDA DA SILVA - DISSERTAÇÃO PPGHT 2016.pdf: 826053 bytes, checksum: 1b591555331ff37d8d5596f2cb55e161 (MD5) / Made available in DSpace on 2018-05-18T15:11:35Z (GMT). No. of bitstreams: 1 GLEYCE LACERDA DA SILVA - DISSERTAÇÃO PPGHT 2016.pdf: 826053 bytes, checksum: 1b591555331ff37d8d5596f2cb55e161 (MD5) Previous issue date: 2016 / O melão é uma hortaliça de fruto muito consumido no mundo; no Brasil apresenta elevada expressão econômica e social, sobretudo na região Nordeste em razão das condições de solo e clima serem adequadas ao crescimento e desenvolvimento das plantas e dos frutos. O objetivo desse trabalho foi avaliar a partição de massa, a produção e a qualidade de frutos de melão em função de alterações na relação fonte:dreno. O experimento foi instalado na Universidade Federal de Campina Grande, no Centro de Ciências e Tecnologia Agroalimentar, Campus Pombal – PB, em esquema fatorial do tipo 3 x 4 no delineamento de blocos casualizados, com cinco repetições. O primeiro fator constava do número de frutos por planta (1, 2 e fixação livre de frutos) e o segundo fator foi constituído da poda da haste principal em quatro épocas (35, 40, 45 e 50 dias após o transplante - DAT). As plantas do híbrido Hopey King do grupo Cantaloupe foram cultivadas no espaçamento de 2,0 x 0,4 m. Foram avaliadas as características de acúmulo de massa seca, produtividade e qualidade dos frutos. Diante dos resultados foi encontrado maior valor de massa seca de folha, haste e área foliar em plantas conduzidas com apenas um fruto; no entanto, estas apresentaram menor valor de massa seca de fruto e da parte área. A condução da planta com fixação livre proporcionou frutos de menor massa, porém, devido ao seu maior número por hectare elevou a produtividade em relação a plantas com um e dois frutos. O número de frutos por planta e a massa dos frutos foram maiores quando as plantas foram podadas aos 50 e 35 DAT. O teor de sólidos solúveis não se modificou com a fixação de frutos na planta, porém em relação à poda da haste principal, verificou-se redução do seu valor de 9,5 para 8,0%, ou seja, 15,7% a medida que se retardou a poda da haste dominante de 35,0 para 50,0 DAT, evidenciando que frutos provenientes de plantas podadas mais precocemente provavelmente receberam maior quantidade de fotoassimilados que foram direcionados para o crescimento e maturação dos frutos. A produtividade do meloeiro elevou-se quando a planta foi poda mais precocemente, aos 35 DAT. / Melon is a much-consumed fruit vegetable in the world; In Brazil has a high economic and social expression, especially in the Northeast region, because soil and climate conditions are adequate for the growth and development of plants and fruits. The objective of this work was to evaluate the mass partition, production and quality of melon fruits as a function of changes in source: drain. The experiment was installed at the Federal University of Campina Grande, in the Agro - Food Science and Technology Center, Campus Pombal - PB, in a 3 x 4 factorial design in a randomized complete block design with five replications. The first factor consisted of the number of fruits per plant (1, 2 and free fixation of fruits) and the second factor was constituted by pruning of the main stem in four seasons (35, 40, 45 and 50 days after transplanting - DAT). The Hopey King hybrid plants of the Cantaloupe group were grown at 2.0 x 0.4 m spacing. It was evaluated the characteristics of dry mass accumulation and productivity and fruit quality. In view of the results, it was found higher leaf dry matter, stem and leaf area in plants with only one fruit; however, these presented lower value of dry fruit mass and area. Plant management with free fixation provided lower mass fruit however, due to its higher number per hectare; it increased productivity in relation to plants with one and two fruits. The number of fruits per plant and fruit mass were higher when the plants were pruned at 50 and 35 DAT. The soluble solids content did not change with the fixation of fruits in the plant, but in relation to the pruning of the main stem, a reduction of its value from 9.5 to 8.0% was verified, that is, 15.7% a As the pruning of the dominant stem was delayed from 35.0 to 50.0 DAT, evidencing that fruits from pruned plants probably received a greater quantity of photoassimilates that were directed to the growth and maturation of the fruits. The productivity of the melon increased when the plant was pruned earlier, at 35 DAT.