Effect of seed size at sowing on grain yield of PBA Nasma faba bean

Take home messages

• At present, there is no evidence to suggest that seed size at sowing has an impact on grain yield in cultivar PBA Nasma
• Seed size at sowing is positively related to seed size at harvest
• Further experimentation is needed

Introduction

In cereals, large initial seed size frequently confers distinct advantages in terms of seedling vigour, hardiness, improved stand establishment, and higher productivity (Grieve and Francois, 1992). Spilde (1988) found, for barley and wheat that grain produced from small-sized seed averaged 4 and 5% less yield than that from medium sized seed and 6 and 8% less yield than that from large-sized seed, respectively.

However, studies comparing faba bean genotypes of different seed sizes indicated a negative relationship between seed mass and grain yield (Laing et al., 1984; White and González, 1990; White et al., 1992; Sexton et al., 1994). Lima et al(2005) found faba bean plants originating from small seed presented a higher relative growth rate and net assimilation rate than plants from large seed. Large seed did not affect grain yield, but reduced the number of seeds per pod, increased the 100-seed mass, and reduced the harvest index.

The new faba bean cultivar, PBA Nasma, produces very large seed averaging 70g/100 seeds compared to cultivar Doza, at 50g/100 seeds . An experiment was conducted to examine the effect of seed size at sowing, at a fixed population, on grain yield and seed size distribution at harvest.

What did we do?

Seed supply for this newly released cultivar was in limited supply which restricted experimentation to two sites (TAI and TARC) in 2015.

The seed was passed through a set of nested circular mesh sieves and partitioned into four seed size categories; < 7mm, 7-8mm, 8-9mm, >9mm. The corresponding 100 seed weights for the seed size categories,  < 7mm, 7-8mm, 8-9mm, >9mm; were 34.6, 48.1, 69.5 and 90.0g, respectively.

Randomised complete block experiments consisting of the four seed size treatments and four replicates were sown at target plant densities of 20 and 10 plants/m² at TAI and TARC, respectively.

What did we find?

The seed size distribution of the 25kg seed lot used to obtain the seed categories for sowing these experiments is contained in Figure 1. The predominant seed size was the 8-9mm category which accounted for 72% of the total seed supply.

All plots attained their target plant densities (data not shown). At TAI, plants grown from the largest size seed produced 19% and 8% more biomass than the small seed size category at 25^th June and 3^rd August, respectively. Seed size categories were scored for frost damage on the 7^th of August but there was no significant difference.

Figure 1. Seed size distribution and number of seeds per category for the seed lot used for sowing experiments.

Table 1 contains data on the effect of seed size category at sowing on plant height, height to top pod, grain yield and hundred seed weight for the TAI experiment, and grain yield and 100 seed weight for the TARC experiment.

At TAI, the plants grown from seed smaller than 7mm in size were significantly shorter than all other seed categories while there was no difference in height to top pod across the seed categories (see Table 1). There was also no significant difference in grain yield between any of the seed size categories. Hundred seed weight did vary significantly and the large seed category, on average, produced heavier grain than the small seed category.

At TARC, grain yield was significantly higher for the two large seed size categories compared to the very small seed category (by 13%). Hundred seed weight had a similar response to seed size category as found at TAI, 100 seed weight increasing with seed size at sowing (see Table 1).

Table 1.  Effect of seed size category at sowing on plant height, height to top pod, grain yield and hundred seed weight for TAI and grain yield and hundred seed weight for TARC

Values with the same letter are not significantly different at P>0.05.

Conclusion

Plants grown from large seeds were taller and had significantly more biomass than the plants grown from small seed. However, this did not translate into a significant difference in grain yield at TAI but did in the TARC experiment. There may be an interaction with plant density and seed size given these different results (TAI 20 and TARC 10 plants/m²). These results are similar to that of Agung and McDonald (1998) in South Australia where yields for cultivar Fiord averaged about 400 g/m 2 but were not consistently related to seed size, although the highest yielding accession at their sites were large-seeded.

The size of seed produced at harvest was positively related to seed size with the largest seed category producing the biggest size seed compared to the small seed category (see Table 1) at both experimental sites.

Acknowledgements

The research undertaken as part of project DAN00171 is made possible by the significant contributions of growers through both trial cooperation and the support of the GRDC. The authors would like to thank them for their continued support. Thanks to Mat Grinter, Michael Nowland and Jayne Jenkins and Scott Richards (all NSW DPI) for their technical assistance in the trial program.

References

S. Agung and G. K. McDonald (1998). Effects of seed size and maturity on the growth and yield of faba bean (Vicia faba L.). Australian Journal of Agricultural Research 49(1) 79 - 88

C. M. Grieve, L. E. Francois (1992). The importance of initial seed size in wheat plant response to salinity. Plant and Soil, Vol 147, Issue 2, pp 197-205

Laing DR, Jones PG, Davis JHC (1984) Common bean (Phaseolus vulgaris L.). In: Goldsworthy PR, Fisher NM (eds), The Physiology of Tropical Field Crops, pp.305-351. John Wiley, New York, USA.

Elvis Rodrigues Lima; Aline Silva Santiago; Adelson Paulo AraújoII, Marcelo Grandi Teixeira (2005). Effects of the size of sown seed on growth and yield of common bean cultivars of different seed sizes, Braz. J. Plant Physiol. vol.17 no.3       

Sexton PJ, White JW, Boote KJ (1994) Yield-determining processes in relation to cultivar seed size of common bean. Crop Sci. 34:84-91.

L. A. Spilde (1988). Influence of Seed Size and Test Weight on Several Agronomic Traits of Barley and Hard Red Spring Wheat. Journal of Production Agriculture, Vol. 2, No. 2, p. 169-172

White JW, González A (1990) Characterization of the negative association between seed yield and seed size among genotypes of common bean. Field Crops Res. 23:159-175

White JW, Singh SP, Pino C, Rios BMJ, Buddenhagen I (1992) Effects of seed size and photoperiod response on crop growth and yield of common bean. Field Crops Res. 28:295-307.

Contact details

Dr Andrew Verrell
NSW Department Primary Industries
Mb: 0429 422 150
Email:  andrew.verrell@dpi.nsw.gov.au

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