Initial germination of seeds and seedling emergence are the key factors in achieving uniform, well established field stands. Soil moisture is necessary for seed germination and seedling growth but, under semi-arid Mediterranean conditions soil moisture in the upper layer is limited and seeds may be exposed to frequent dehydration. However, deep sowing could ensure adequate seed-zone moisture before germination and thereby enhance seedling establishment. Deep sowing could also be important for avoiding the phytotoxicity of pre-emergence herbicides and preventing seed removal by predators.

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Since the early 1970s the ‘Green Revolution’ has led to a significant improvement in wheat yields, through incorporation of Reduced height (Rht) alleles to produce semi-dwarf cultivars. Rht-B1 and Rht-D1 (formerly Rht1and Rht2) encode DELLA proteins (named after their conserved N-terminal D-E-L-L-A amino acid motif), which act as repressors of gibberellin (GA)-responsive growth. The Rht-B1b and Rht-D1b mutations are gain-of-function mutations that impair GA signaling and thereby confer dwarfism through constitutive repression of cell division and elongation. The shortened stem of GAI wheat results in liberation of more assimilates to the parallel process of spike development, thereby contributing to harvest index (HI) improvement and, consequently, increased total grain yield. The Rht improves lodging resistance and enables increased application rates of chemical fertilizers.

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However, modern GAI wheat cultivars have short coleoptiles (the sheath-like structure that protects the elongating seedling as it emerges through the soil surface), therefore they will not establish well if sown too deep. In attempting to counter these problems of establishment under deep sowing, several alternative dwarfing genes that confer Rht while retaining responsiveness to endogenous gibberellin (GAR) have been characterized. Wheat lines with enhanced early vigor are also evaluated for weed competitiveness as early plant cover could be use as integrated weed management tool.