Growth Response of Rice (Oryza sativa) and Red Rice (O. sativa) in a Replacement Series Study¹

Abstract

A replacement series study was conducted in a greenhouse in 1998 and 1999 to evaluate the interference interactions among two rice cultivars and two red rice ecotypes. Plants were established in proportions of 3:0, 2:1, 1:2, and 0:3 (rice–red rice) plants/pot. Relative yield of Kaybonnet based on the shoot dry weight was lower than that of KatyRR or LA3, whereas PI 312777 was comparable to that of KatyRR and LA3. These results indicate that Kaybonnet was less competitive than PI 312777 when contrasted with KatyRR and LA3 red rice ecotypes. Kaybonnet (commercial rice cultivar) was dominated by both KatyRR (suspected rice × red rice cross) and LA3 (tall red rice ecotype) in tiller production, whereas PI 312777 (weed-suppressive cultivar) was comparable to either KatyRR or LA3. Both KatyRR and LA3 considerably reduced the leaf area of Kaybonnet. In contrast, PI 312777 reduced the growth of KatyRR, and its leaf area was comparable to that of LA3. The data suggest that high tillering capacity, as demonstrated by PI 312777, should be considered when breeding for rice cultivars that are competitive against weeds. This agronomic characteristic of rice may improve the success of reduced herbicide rate application programs.

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.…”

Competitividade relativa entre cultivares de arroz irrigado e biótipo de capim-Arroz (Echinochloa spp.)

“…A interpretação dos dados de experimento substitutivo resulta em medida da competitividade entre as espécies, com base na resposta relativa da variável em estudo, podendo ser: a produção de massa seca da parte aé-rea, área foliar, estatura, afilhamento e índice de cobertura do solo; contudo, a resposta é dada pela variação da proporção de plantas associadas (Crotser & Witt, 2000;Estorninos Jr. et al, 2002;Cralle et al, 2003;Vida et al, 2006). Em experimentos conduzidos em séries substitutivas, geralmente as culturas demonstram maior habilidade competitiva do que as espécies daninhas; isso ocorre porque, em campo, o efeito da planta daninha sobre a cultura se deve, principalmente, ao nível de infestação e não à sua habilidade competitiva individual (Vilá et al, 2004).…”

Interactions Between Weedy Rice and Cultivated Rice in Italy

“…These results are partly in agreement with the information available from the literature. Several studies pointed out that the effects of weedy rice interference on dynamics of different growth parameters of rice can vary from not significant to strong, according to the experimental conditions (Montealegre and Clavijo, 1991;Kwon et al, 1991a;Estorninos et al, 2000Estorninos et al, , 2002Eleftherohorinos et al, 2002). For instance, in this study a 5% of plant height reduction due to competition was recorded in Thaibonnet in 1997 only, while Kwon et al (1991a) reported a reduction of 4.3% in the cultivar Lemont and 6% in the cultivar Newbonnet, with an infestation of 10 plants m -2 .…”