ABSTRACT
Nitrogen is crucial for plant growth and development, and improving nitrogen use efficiency (NUE) is a viable strategy for reducing dependence on nitrogen inputs and promoting sustainability. While the benefits of heterosis in corn are well known, the physiological mechanisms underlying this phenomenon in popcorn are less understood. We aimed to investigate the effects of heterosis on growth and physiological traits in four popcorn lines and their hybrids under two contrasting nitrogen conditions. We evaluated morpho-agronomic and physiological traits such as leaf pigments, the maximum photochemical efficiency of PSII, and leaf gas exchange. Components associated with NUE were also evaluated. N deprivation caused reductions of up to 65% in terms of plant architecture, 37% in terms of leaf pigments, and 42% in terms of photosynthesis-related traits. Heterosis had significant effects on growth traits, NUE, and foliar pigments, particularly under low soil nitrogen conditions. N-utilization efficiency was found to be the mechanism favoring superior hybrid performance for NUE. Non-additive genetic effects were predominant in controlling the studied traits, indicating that exploring heterosis is the most effective strategy for obtaining superior hybrids to promote NUE. The findings are relevant and beneficial for agro farmers seeking sustainable agricultural practices and improved crop productivity through the optimization of nitrogen utilization.
ABSTRACT
Phosphorus is a non-renewable natural resource that will run out of reserves in the upcoming decades, making it essential to understanding the inheritance of nutrient use efficiency for selecting superior genotypes. This study investigated the additive and non-additive effects of commercially relevant traits for the popcorn crop (grain yield-GY, popping expansion-PE, and expanded popcorn volume per hectare-PV) in different conditions of phosphorus (P) availability in two locations in Rio de Janeiro State, Brazil. Six S7 lines previously selected for P use-L59, L70, and P7, efficient and responsive; and L54, L75, and L80, inefficient and non-responsive-were used as testers in crosses with 15 progenies from the fifth cycle of intrapopulation recurrent selection of UENF-14, with adaptation to the North and Northwest regions of Rio de Janeiro State. Using the Griffing diallel analysis, P use efficiency was predominantly additive in the expression of PE, and non-additive effects were prominent for GY and PV. For obtaining genotypes that are efficient for phosphorus use, it is recommended that heterosis with parents that provide additive gene accumulation for PE be explored.
ABSTRACT
We investigated the proteomic profiles of two popcorn inbred lines, P2 (N-efficient and N-responsive) and L80 (N-inefficient and nonresponsive to N), under low (10% of N supply) and high (100% of N supply) nitrogen environments, associated with agronomic- and physiological-related traits to NUE. The comparative proteomic analysis allowed the identification of 79 differentially accumulated proteins (DAPs) in the comparison of high/low N for P2 and 96 DAPs in the comparison of high/low N for L80. The NUE and N uptake efficiency (NUpE) presented high means in P2 in comparison to L80 at both N levels, but the NUE, NUpE, and N utilization efficiency (NUtE) rates decreased in P2 under a high N supply. DAPs involved in energy and carbohydrate metabolism suggested that N regulates enzymes of alternative pathways to adapt to energy shortages and that fructose-bisphosphate aldolase may act as one of the key primary nitrate responsive proteins in P2. Proteins related to ascorbate biosynthesis and nitrogen metabolism increased their regulation in P2, and the interaction of L-ascorbate peroxidase and Fd-NiR may play an important role in the NUE trait. Taken together, our results provide new insights into the proteomic changes taking place in contrasting inbred lines, providing useful information on the genetic improvement of NUE in popcorn.
Subject(s)
ProteomicsABSTRACT
The aim of this study was to evaluate the contribution of pure stands of Eucalyptus camaldulensis and Acacia mangium for litter deposition and nutrient return in a pit of clay extraction in northern Rio de Janeiro (RJ). We conducted a randomized block design experiment with two treatments and three replications. For the evaluation of the annual deposition of litter and nutrients (N, P, K, Ca and Mg), we used circular collectors during a year (from July 2006 to June 2007). The planting of Acacia mangium in clay extraction pits contributed with the largest annual deposition of litter and with a litter of better quality compared to Eucalyptus camaldulensis, with higher levels of P and N and lower C:N and polyphenol:N ratios. This fact possibly allows higher rates of decomposition by edaphic microorganisms and, hence, a faster release of these nutrients to the soil. In addition, the planting of legumes showed higher annual deposition of P and N.
O objetivo deste estudo foi avaliar a contribuição de plantios puros de Eucalyptus camaldulensis (Eucalipto) e Acacia mangium (Acácia) na deposição de serapilheira e retorno de nutrientes em uma cava de extração de argila na região norte fluminense (RJ). Realizou-se um experimento, cujo delineamento utilizado foi o de blocos casualizados com dois tratamentos e três repetições. Para a avaliação do aporte anual de serapilheira e nutrientes (N, P, K, Ca e Mg), utilizaram-se coletores circulares, durante o período de um ano (julho de 2006 a junho de 2007). O plantio de Acacia mangium na cava de extração de argila contribuiu com o maior aporte anual de serapilheira total, bem como, uma serapilheira de melhor qualidade em relação ao Eucalyptus camaldulensis, apresentando maiores teores de P e N e menores relações C:N e Polifenol:N. Este fato possivelmente permite maiores taxas de decomposição pelos microrganismos edáficos, e consequente mais rápida liberação desses nutrientes para o solo. Além disso, o plantio da leguminosa apresentou maior aporte anual de P e N.
Subject(s)
Crop Production , Clay , Food , Acacia , Eucalyptus , FabaceaeABSTRACT
Este trabalho foi realizado em maracujazeiro amarelo (Passiflora edulis Sims f. flavicarpa) cultivado em condições de campo, no município dos Campos do Goytacazes-RJ, com o objetivo de determinar os teores de rutina, vitexina e flavonóides totais e dos nutrientes N, P, K, Ca, Mg, S, B, Fe, Zn, Mn e Cl em folhas de diferentes posição no ramo. O experimento constou de 10 tratamentos, que consistiam na coleta das folhas 1 (mais nova) a 10 (mais velha) de um mesmo ramo, com quatro repetições. A amostragem foliar foi feita em março de 2004 e cada amostra constou de 20 folhas coletadas de 20 plantas por repetição. Os teores de rutina, vitexina e flavonóides totais variaram em função da posição ou idade das folhas, sendo maiores nas folhas mais jovens ou na região apical dos ramos do maracujazeiro amarelo. Os teores de flavonóides totais, expressos em vitexina, diminuíram da folha 1 para a folha 8, de 24,4 para 14,9mg g-1 de matéria seca. Os teores de N, P, K e Zn foram maiores e os de Ca, Mg, B, Cl e Mn foram menores nas folhas mais jovens. Os teores de S e Fe não variaram com a posição da folha no ramo.
The research was carried out in yellow passion fruit plant (Passiflora edulis Sims f. flavicarpa) grown under field conditions in Campos dos Goytacazes-RJ, Brazil, with the aim to evaluate the concentrations of rutin, vitexin, total flavonoids, N, P, K, Ca, Mg, S, B, Fe, Zn, Mn and Cl in leaves at different positions in the branch. The experiment consisted of 10 treatments: leaves 1 (the youngest) to 10 (the olderest) of the same branch, with four replicates. Leaf sampling was done in March 2004, and each sample consisted of 20 leaves from 20 plants. The total concentration of rutin, vitexin and total flavonoids varied in function of the position or age of leaves, being higher in youngest leaves or in the aplical region of the plant branches. The total flavonoids concentration decreased from leaf 1 to leaf 8 of the branch 24.4 and 14.9mg g-1 of dry matter, respectively. The concentrations of N, P, K and Zn were higher in the youngest leaf but the concentrations of Ca, Mg, B, Cl and Mn were lower. The concentrations of S and Fe did not vary with leaves positions in the branch.
