Different types of rice tiller responses to nitrogen

Experimental field showing rice grown under different nitrogen fertiliser rates (Wang et al.).

Tillering is an important agronomic trait for rice population quality and grain production. In a recent study published in AoB PLANTS, Wang et al. found that nitrogen fertilizer application increased the number of rice tillers, but not every tiller contributed equally to the overall yield. Heterogeneity in tiller yield of rice increased with increasing nitrogen levels. Typically, late emerging tillers contributed less to the grain yield. Under high nitrogen conditions, most of the nutrients were retained in the straw of late emerging tillers; these tillers have high transport efficiency in vascular bundles, but there is less time for nutrients to transport into the grain. Despite the high light intensity, less than half of the light is used for photosynthesis in late emerging tillers. The low activity of enzymes related to grain filling in late emerging tillers is another reason for low yield. The identification of these limiting factors in late emerging rice tillers will assist in closing the “yield gap” between late emerging tillers and early emerging tillers, and will contribute to further increasing rice grain yields.

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