Time to Radicle Protrusion Does Not Correlate with Early Seedling Growth in Individual Seeds of Impatiens and Petunia
Impatiens (Impatiens wallerana Hooker F.) and petunia (Petunia ·hybrida Hort. Vilm.) seeds were imaged usingaflat-bedscanner interfacedwithapersonal computerprogrammed to captureimages every hour. Imageswere used to measure time to radicle protrusion and seedling growth. Time to radicle protrusion was calculated as time to 50% germination or as actual germination for each seed. Seedling growth after germination was calculated from linear regression of growth over time. Radicle protrusion and seedling growth were evaluated as indicators of seed vigor. Both were good indicators of seed vigor in impatiens seed lots. These measurements of vigor were highly correlated for each impatiens seed lot and for pooled seed lots. However, there was little or no correlation between time to radicle protrusion and seedling growth on an individual seed basis. The relationship between germination speed and seedling growth rate observed in impatiens was confirmed in two petunia seed lots. This study supports the use of time to radicle emergence and seedling growth as good indicators of seed vigor. However, it appears that different aspects of seed vigor may be measured by these indicators because there was no relationship between time to radicle protrusion and seedling growth rate on an individual seed basis.
Anatomo-functional bimodality imaging for plant phenotyping: An insight through depth imaging coupled to thermal imaging
As reproductive units, seeds are essential for the survival of plant species and for their role in stand establishment. Seeds are also a crucial input for agriculture, as they are the vector of genetic progress and of different plant protection treatments. Germination is the first step in plant development and is a complex process (Bewley and Black, 1994; Nonogaki et al., 2010; Rajjou et al., 2012). It is a critical phase in the plant life cycle during which quiescent seeds are reactivated to produce seedlings. Germination sensus stricto begins with uptake of water by the seed and terminates with the initiation of growth of the embryo axis and radicle protrusion (Come and Thevenot, 1982; Nonogaki et al., 2007). During this initial stage, seed water content increases in direct relation with the moisture content of the environment, allowing seed reserves to be hydrolyzed and metabolism to restart. Seed water content has to reach a threshold value to allow germination and to maintain this value until the radicle emerges (Bewley and Black, 1994; Kigel and Galili, 1995). Subsequent seedling growth depends
Development of galactomannan‐hydrolyzing activity in the micropylar endosperm tip of tomato seed prior to germination
Development of galactomannan-hydrolyzing activity, that is involved in the weakening of the mechanical restraint of the endosperm, was followed at pre-germinative stages in tomato (Lycopersicon esculentum) seed. Prior to germination the activity developed exclusively in the endosperm portion just adjacent to the radicle tip. In other parts of the endosperm, the activity developed only after germination occurred. Under the conditions where germination was suppressed (far-red light- or ABA-treatment). no activity was detected in the endosperm at the pre-germinative stages. Under the conditions where the inhibition of germination was alleviated (far-red + red or ABA + GA3), the activity developed prior to germination in the endosperm part in front of the radicle tip. Thus, a clear parallel relationship was observed between germinability of the seed and the pre-germinative development of activity in the part of the endosperm portion adjacent to the radicle tip.