Incidence of green soybean seeds as a function of environmental stresses during seed maturation

Abstract

Hot and dry weather conditions during soybean [Glycine max (L.) Merrill] seed maturation can cause forced maturation of the seed, resulting in the production of high levels of green seed, which may be detrimental to seed germination. These stressful conditions were imposed on soybean plants during seed maturation to investigate the production of green seeds and seed quality. Plants of the CD 206 cultivar were grown in a greenhouse until the R5.5 growing stage and then transferred to phytotrons at R6 and R7.2 for stress induction. Plants were subjected to two temperature regimes, high (28ºC to 36ºC) and normal (19ºC to 26ºC), and four soil water availability conditions, control (adequate water supply), 30% gravimetric moisture (GM), 20% GM and no water supply. Seed were harvested at R9. Green seed percentages and 100-seed weights from the lower, middle and upper thirds of each plant were determined. Seed quality was assessed by germination, tetrazolium (viability and vigor) and electrical conductivity tests. Occurrence of green seed varied from 9% to 86%, depending on the severity of the stresses imposed. High temperature, coupled with no water supply at R6, resulted in a pronounced occurrence of green seeds. There was no difference in the percentage of green seeds among the plant segments. Seed quality was negatively affected by the incidence of green seeds. A procedure for screening soybean genotypes in a phytotron for their tolerance and/or susceptibility to the production of green seeds was developed.

Gene expression profiling of the green seed problem in Soybean

“…For over a decade Brazilian soybean growers have been reporting the occurrence of green seeds at the end of the maturation process and it has become a great concern to the soybean market in the last few years ([ 39 , 40 ]). However, chlorophyll retention in seeds is not unique to Brazil or to soybean as it has been reported in other countries and in canola seeds [ 2 – 7 , 37 , 41 – 43 ]. A similar phenotype to chlorophyll retention, called stay-green has been described in leaves and seeds of mutants of different species [ 44 ].…”

“…These are common environmental conditions in tropical areas such as the Brazilian cerrado biome where approximately 45 % of the Brazilian soybean seed production is concentrated (14.5 million hectares) [ 8 ]. Besides the climate, other factors or practices during pre- and post-harvesting, such as application of desiccants and premature harvesting followed by drying at high temperatures are also reported to result in retention of chlorophyll in soybean seeds [ 2 ]. In addition to these environmental factors there is also variation in the susceptibility of soybean cultivars to green seed production under stress.…”

“…The increase of environmental stress over the past decades is a growing concern worldwide especially for agricultural productivity. Efforts have already been made to understand the influence of growing conditions and drying processes on the retention of green pigments in soybean seeds and how it affects the physiological and biochemical characteristics of these seeds [ 2 , 3 , 9 , 31 , 32 ]. So far, the molecular mechanisms of Chl degradation in seeds and consequently of Chl retention remain unsolved.…”

Size and vigor of Anadenanthera colubrina (Vell.) Brenan seeds harvested in Caatinga areas

“…imbibition, speed and germination percentage, reduces plant growth by decreasing cell expansion (Bewley et al, 2012). Even moderate increases in air temperature or decreases in soil water availability are responsible for decreased plant growth and productivity (Pádua et al, 2009;Vile et al, 2012). Despite the fact that size (S) did not present any correlation with the variables G%, FCG and FING, it presented a positive correlation with SG, SDM, RDM, SDME and RDME.…”

Presença de nematoides em plantas de soja: relação com a ocorrência de sementes esverdeadas e seu potencial fisiológico

“…Estresses ambientais, como altas temperaturas e períodos de seca durante a maturação, interferindo na degradação da molécula de clorofila e resultando em aumento na ocorrência de sementes esverdeadas têm sido destacado por diversos autores MULLEN, 1991;BOHNER, 2003;PÁDUA et al, 2009a, 2009b, 2012 COSTA et al, 2001;BOHNER, 2003;PUPIM et al, 2005;PÁDUA et al, 2005PÁDUA et al, , 2007ZORATO et al, 2007;FRANÇA NETO et al, 2012 (HOOPER, 1986). As raízes foram processadas e trituradas em liquidificador e a suspensão resultante foi vertida em peneiras de 60 e 500 "mesh", respectivamente.…”