Shading and Thinning Effects on Seed and Shoot Dry Matter Increase in Determinate Soybean during the Seed‐Filling Period

Abstract

under drought conditions (Kobata et al., 1992). Both cereal crops clearly change their growth phase from The relationship between seed and shoot dry matter increase (R S/W ) during the seed-filling period (SFP) can reflect the balance between vegetative to reproductive stages, and the potential S the assimilate supply and the sink capacity of harvest organs. In a barely changes once the SFP begins (Evans, 1996). In 2-yr experiment, the R S/W in determinate soybean [Glycine max (L.) soybean, however, active stem and leaf growth continue Merr.] during SFP was investigated under various growing conditions after onset of SFP because flowering starts with vegetainduced by shading and thinning for plants grown under both standard tive growth earlier in the growing season than in most and reduced densities. The R S/W approximated a positive linear regrescereal crops (Ojima and Fukui, 1966). Hence, in soysion in both experiments. Slopes of the lines were less than 0.5 and did not vary within the same year even if plant density was reduced. bean, the potential S may change with the W. If the The shoot dry matter increase (W) hence seemed to directly determine potential S changes with W, the S should not reach a seed dry matter increase (S). A positive relationship between total limit such as the plateau observed in Case 1. If so, the pod number and W or S was observed in both years. Only minimal R S/W may be typed as three cases (Fig. 1, Cases 2-4). In changes in seed numbers per pod and individual seed weight were Case 2, S during the SFP is equal to W (S ϭ W), and observed, regardless of the treatment applied. A positive relationshipthere is no net transfer of assimilate reserves to the also existed between total pod number and the number of branch nodes, and hence W increased S via increase in the number of branch seed. In Case 3, S is greater than W due to net transfer node bearing pods. Half the current assimilate product during SFP of assimilate reserves from the stem to the seed. Conappeared to be used for increase of vegetative plant parts. This deterversely, in Case 4, S is less than W because excess dry mined total pod number and hence potential S. Determinate soybean matter is stored in the stem rather than in the seed. is thus very different from cereal crops, in which almost all the currentThe soybean harvest index (HI), the ratio of seed assimilate during the SFP is appropriated to S. The stability of the yield to total biomass at maturity, has been considered harvest index in soybean reflects the important effect of the W on pod establishment during SFP.

Influence of Plant Population and Weed Control Treatments on Associated Weeds, Growth, Yield and Quality of Faba Bean

“…There are several reports suggested that increasing population density up to 33.3 or 44.4 plant/m 2 led to a pronounced increase in the plant height (El-Douby et al, 1996 andAbdel-Aziz andShalaby, 1999). On the other hand, Kakiuchi and Kobata (2004) revealed that lower plant density increased faba bean yield attribute i.e. pod number/plant while, the higher plant population decreased the pods number/plant.…”

Screening Soybean for Adaptation to Relay Intercropping Systems: Associations between Reproductive Organ Abscission and Yield

“…The process of soybean flowering, pod formation, and yield formation is also the process of accumulation and distribution of its internal substances. Reasonable and effective biomass accumulation and distribution will increase the number and weight of soybean seeds, which is an important approach for improving soybean yield [22,24]. Researchers usually use different growth parameters to measure the crop's growth trajectory in terms of crop growth rate (CGR), relative growth rate (RGR), and net assimilation rate (NAR) [25].…”