Evaluation of physiological traits in upland rice for adaptation to no-tillage system

Madari

et al. 2012

Pesq. agropec. bras.

The objective of this work was to evaluate the effect of eucalyptus biochar on the transpiration rate of upland rice 'BRSMG Curinga' as an alternative means to decrease the effect of water stress on plant growth and development. Two-pot experiments were carried out using a completely randomized block design, in a split-plot arrangement, with six replicates. Main plots were water stress (WS) and no-water stress (NWS), and the subplots were biochar doses at 0, 6, 12 and 24% in growing medium (sand). Total transpirable soil water (TTSW), the p factor - defined as the average fraction of TTSW which can be depleted from the root zone before water stress limits growth -, and the normalized transpiration rate (NTR) were determined. Biochar addition increased TTSW and the p factor, and reduced NTR. Consequently, biochar addition was able to change the moisture threshold (p factor) of the growing medium, up to 12% maximum concentration, delaying the point where transpiration declines and affects yield.

“…'BRSMG Curinga' is described as a medium cycle plant, with 11 to 12 leaves in the main stem (Heinemann et al, 2009). It is considered a modern cultivar and was created in 2005.…”

Section: Methodsmentioning

confidence: 99%

Transpiration response of upland rice to water deficit changed by different levels of eucalyptus biochar

Pereira

Madari

et al. 2012

Pesq. agropec. bras.

“…One third of N was applied at sowing and the remaining was top-dressed at two equal rates at the beginning of tillering, V4 stage of the Counce et al (2000) scale, and at panicle differentiation (PD), R1 stage of Counce et al (2000) scale. Four upland rice genotypes (BRS Primavera, BRSMG Curinga, BRS Soberana, and Douradão) were chosen due to their difference in physiological traits (Heinemann et al, 2009) as well as due to their use as parental lines in Embrapa's breeding programs (Breseghello et al, 2008). The BRS Primavera, BRSMG Curinga and BRS Soberana are considered modern cultivars and Douradão an old traditional cultivar.…”

Section: Methodsmentioning

confidence: 99%

“…They differ in number of leaves in the main stem and consequently in the development cycle, BRSMG Curinga being the latest (medium cycle) and BRS Soberana the earliest cultivar (early cycle). The Haun index for the four cultivars is described in detail in Heinemann et al (2009). The observed data used in this study come from two experiments with sowing dates in 27/08/2008 and 10/17/2008.…”

Section: Methodsmentioning

confidence: 99%

Transpiration rate response to water deficit during vegetative and reproductive phases of upland rice cultivars

Sci. agric. (Piracicaba, Braz.)

Stone

Fageria

2011

Self Cite

Water deficit is one of the most important abiotic stress limiting upland rice yield in the "Cerrado" region of Brazil. Selecting drought tolerant cultivars is an important strategy to overcome this constraint. Two greenhouse experiments were conducted at Santo Antônio de Goiás, state of Goiás, Brazil, to compare the response of normalized transpiration rate (NTR) of three modern (BRS Primavera, BRSMG Curinga and BRS Soberana) and one traditional (Douradão) upland rice cultivars to soil water deficit during the vegetative and reproductive growth stages. This information will support breeding strategies to improve rice yield in a drought-prone target population environments (TPE) in Brazil. NTR and the total fraction of transpirable soil water (FTSW) were calculated, plotted and adjusted according to a sigmoid non-linear model. The p factor, defined as the fraction of available soil water that can be removed from the root zone before water deficit occurs, was calculated by assuming that it occurs when NTR is equal to 0.95. Modern cultivars had a higher value of p for the reproductive phase than for the vegetative phase. In addition, these cultivars are better adapted to express their potential yield in regions with low intensity and occurrence of water stress and the traditional cultivar is enable to better support adverse conditions of water stress. It can be concluded that there is need to precisely characterize drought patterns in TPEs. This information can focus the breeding program to improve drought tolerance in modern upland rice cultivars. Key words: Oryza sativa, available soil water, dry spells, fraction of soil water transpiration Resposta da taxa de transpiração ao déficit hídrico nas fases vegetativa e reprodutiva de cultivares de arroz de terras altasRESUMO: A deficiência hídrica é considerada um dos mais importantes estresses abióticos que limitam a produtividade do arroz de terras altas no Cerrado. Uma estratégia para minimizar os efeitos da estiagem durante o período chuvoso na produtividade do arroz de terras altas é o uso de cultivares com mecanismos de tolerância à seca. Foram conduzidos dois experimentos em casa de vegetação em Santo Antônio de Goiás, GO, Brasil, para avaliar a resposta da taxa de transpiração normatizada (NTR) de três cultivares modernas (BRS Primavera, BRSMG Curinga e BRS Soberana) e uma tradicional (Douradão) de arroz de terras altas ao déficit hídrico no solo nas fases vegetativa e reprodutiva. Essa informação visa apoiar estratégias de melhoramento para incrementar a produtividade do arroz em ambientes para população alvo (TPEs) propensos à seca no Brasil. Foram calculadas a NTR e a fração da água do solo transpirável (FTSW) e esses dados foram ajustados segundo um modelo sigmoidal não linear. O fator p, definido como a fração de água disponível no solo que pode ser retirada da zona radicular antes de ocorrer deficiência hídrica, foi calculado assumindo-se que ele ocorre quando NTR for igual a 0,95. Para os cultivares modernos foram observados valores maiores d...

“…Características fisiomorfológicas dessa cultivar estão descritas em Heinemann et al (2009). Esta cultivar foi parametrizada e validada para o modelo ORIZA/APSIM 2000 e os coeficientes fenológicos utilizados estão descritos em Lorençoni et al (2010).…”

Section: Methodsunclassified

Simulação do manejo do nitrogênio em arroz de terras altas com o modelo ORYZA/APSIM 2000

Stone

Rev. bras. eng. agríc. ambient.

2012

Self Cite

R ESU M OÉ importante definir a estratégia de manejo da adubação nitrogenada para o arroz de terras altas, pois o nitrogênio é o nutriente mais absorvido pelas plantas dessa cultura e, devido à facilidade de lixiviação no solo, pode poluir o meio ambiente. Objetivou-se, com este trabalho simular, com o modelo ORYZA/ APSIM 2000, diferentes estratégias de manejo da adubação nitrogenada visando maximizar a produtividade e minimizar a lixiviação de N. Na simulação foi considerada a aplicação da dose de 100 kg ha -1 de N em cinco modos: TP -1/5 na semeadura, 2/5 no início do perfilhamento (IP) e 2/5 na diferenciação da panícula (DP); T1 -todo na semeadura; T2 -todo aos 20 dias antes da semeadura; T3 -1/5 na semeadura e 4/5 no IP e T4 -1/5 na semeadura e 4/5 na DP, os quais foram combinados com cinco datas de semeadura: 01/11, 15/11, 01/12, 15/12 e 31/12. O parcelamento da adubação nitrogenada mostrou-se como a estratégia com maior probabilidade de resultar em altas produtividades do arroz de terras altas. Quando não se utiliza essa estratégia, a probabilidade de perdas de nitrogênio por lixiviação é maior. Há maior probabilidade de se obter altas produtividades em datas de semeadura precoces a partir de 01/11, apesar da semeadura tardia contribuir para redução nas perdas de nitrogênio por lixiviação. Palavras-chave:Oryza sativa, adubação nitrogenada, lixiviação de N, data de semeadura Simulation of nitrogen management in upland rice with ORYZA/APSIM 2000 model A B ST R A C T It is important to define nitrogen management strategy for upland rice crop, because nitrogen is the nutrient more absorbed by rice plants and, due to the ease of leaching in soil, it can pollute the environment. This study aimed to simulate, based on ORYZA/APSIM 2000 model, different strategies for nitrogen fertilization management to maximize the productivity and minimize the N leaching. In the simulation, five application modes with an application rate of 100 kg N ha -1 were considered: TP -1/5 at sowing, 2/5 at the beginning of tillering (T) and 2/5 at panicle differentiation (P); T1 -all at sowing; T2 -all at 20 days before sowing; T3 -1/5 at sowing and 4/5 at T and T4 -1/5 at sowing and 4/5 at P. Application modes were combined with five sowing dates: 01/11, 15/11, 01/12, 15/12 and 31/12. Nitrogen fertilizer split applications showed to be the strategy most likely to result in high yields of upland rice. When this strategy is not used, the probability of nitrogen losses by leaching is higher. There is higher probability of obtaining higher yields in the earliest sowing dates, from 01/11, despite the late sowing contribute to reduction in nitrogen losses by leaching.