Wheat and Italian ryegrass (Lolium multiflorum) competition as affected by phosphorus nutrition

Abstract

A greenhouse experiment used a replacement series design to compare the vegetative growth 6 wk after emergence in pure cultures and mixtures of winter wheat and Italian ryegrass, with phosphorus (P) levels recommended by soil testing. The planting proportions of wheat and Italian ryegrass were 100 and 0%, 75 and 25%, 50 and 50%, 25 and 75%, and 0 and 100%, respectively. There was no alleopathic interaction between the species. Both species in all pure and mixed cultures had substantially less growth in the low-P than in the recommended P treatment. However, the relative performance of the two species differed between P treatments. In the recommended P treatment in pure culture, Italian ryegrass had more tillers and greater root weight and length than wheat. Pure culture wheat in the low-P treatment exceeded pure culture Italian ryegrass in leaf area, weights of leaves, stems, and roots, and root length. Thus, the growth of wheat was inhibited less by P deficiency than the growth of Italian ryegrass in pure culture. In the 50:50 mixture of the recommended P treatment, wheat had greater leaf, stem, and root weights than Italian ryegrass. In the 50:50 mixture of the low-P treatment, the two species were very similar in growth, except that Italian ryegrass had about three times more tillers than did wheat. Whereas P deficiency limited the growth of wheat less than Italian ryegrass in pure culture, P deficiency did not affect the relative competitiveness of Italian ryegrass as much as wheat in mixed cultures. The ability of Italian ryegrass to compete with wheat when P was limiting may result from a difference in root growth. Italian ryegrass had a greater fresh root length to fresh root weight ratio than did wheat in the low-P treatment in pure culture and in the 50:50 mixture. The greater surface area of Italian ryegrass roots likely enhanced the competitiveness of Italian ryegrass relative to wheat under P-deficit conditions. Thus, the use of the recommended P nutrition from soil testing may be a key component to diminish Italian ryegrass competition in wheat fields.

Tillering of two wheat genotypes as affected by phosphorus levels

“…distichum L.) (PRYSTUPA et al, 2003). Cralle et al (2003) observed that increasing P supply favored emergence of viable tillers in wheat plants even under severe conditions of competition (1:1) with Lolium multiflorum. Prystupa et al (2003) showed that the negative effects of reducing P availability on wheat tillering are more significant than decreasing N supply.…”

“…Reduced P availability delays the beginning of tiller emergence stage (VALLE; CALDERINI, 2010), which is the characteristic most affected by P deficiency in wheat (CRALLE et al, 2003;YASEEN;MALHI, 2010) and barley (Hordeum vulgare spp. distichum L.) (PRYSTUPA et al, 2003).…”

Competitividade relativa de cultivares de arroz irrigado com Aeschynomene denticulata

“…Determination of competitive interactions between crops and weeds requires appropriate experimental designs and methods of analysis, and the conventional replacement series experiments are the most used to clarify these relationships (Agostinetto et al, 2013;Cralle et al, 2003;Crotser & Witt, 2000;Estorninos et al, 2002;Roush et al, 1989;Vida et al, 2006). In these experiments, the crops generally achieve greater competitive ability than weeds.…”

Crescimento da mandioca e plantas daninhas em resposta à adubação fosfatada

“…Esse fato foi observado por Cralle et al (2003) que relataram que o crescimento de plantas de trigo foi menos inibido, em solo com deficiência de P, do que o crescimento da espécie daninha Lolium multiflorum.…”