Effect of soil hardness on the growth and yield of supernodulating soybean [Glycine max] cultivar Sakukei 4 under field conditions
2006
Shimamura, S.(National Inst. of Crop Science, Tsukuba, Ibaraki (Japan)) | Takahashi, M. | Nohara, T. | Nakamura, T. | Nakayama N. | Yamamoto, R. | Kim, Y.H. | Shimada, S.
The yield of supernodulating soybean cultivar 'Sakukei 4' is stably higher under non-tillage than under tillage conditions. This seems to be due to high sensitivity to soil drought stress of this cultivar, because development of the root system is restricted by supernodulation. To analyze the factor of the sensitivity to drought stress, we compacted the soil to mimic the non-tillage condition and examined the physiological and ecological characteristics of Sakukei 4 and its parental cultivar 'Enrei' in the field with different soil hardness. The development of the root system in Sakukei 4 was inferior to that in Enrei under both soil compacted and non-compacted conditions, which indicated that Sakukei 4 is likely more sensitive to soil drought stress. In Sakukei 4, however, the bleeding rate and stomatal conductance were higher under soil compaction than under non-compaction, indicating that drought stress was mitigated by soil compaction treatment. The shoot dry weight of Sakukei 4 was heavier in soil compaction than in non-compaction from the early growth stage to maturity. The yield of Sakukei 4 in soil compaction was 360-380 g m(-2), which was 50 g m(-2) higher than that in non-compaction in both years. A significant difference between the soil compaction treatment was observed at the 1% level. On the other hand, the compaction treatment had no effect on the growth and yield of Enrei. We conclude that Sakukei 4 has an inferior root system and is more sensitive to soil drought stress than Enrei; however, the water uptake by the root system was improved by soil compaction, which enhanced the volume water content of the soil and mitigated drought stress. Therefore, shoot growth and yield were improved by soil compaction in Sakukei 4.
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