Figure 1.
(a) Radiation (MJ m-2), (b) rainfall (mm), and (c) average temperature during the experimental period.
Figure 2.
(a, b) Plant height of Ischaemum rugosum (I.R.) when grown alone (I.R., R0) or in competition with rice at different seeding rates (R), i.e., 25 (I.R., R25), 50 (I.R., R50), and 100 kg ha−1 (I.R., R100); Rice plant height at different seeding rates: 25 kg ha−1, 50 kg ha−1, and 100 kg ha−1; and (c, d) Ischaemum rugosum (I.R.) and rice plant height under different nitrogen levels, i.e., 0 (I.R., N0, and rice N0), 50 (I.R., N50, and rice N50), 100 (I.R., N100, and rice N100), and 150 kg ha−1 (I.R., N150, and rice N150).
The vertical bars represent standard error of means. The lines represent a three-parameter sigmoid model (y = a/{1+e[−(x−x50)/b]}) fitted to the data. Parameter estimates are shown in Table 1.
Table 1.
Parameter estimates of a three-parameter sigmoid model (y = a/{1+e[−(x−x50)/b]}, where a is the maximum height, leaf number, or tiller per plant; d50 is the time (days after planting) to reach 50% of final height, leaf number, or tiller; and b is the slope at time x) fitted to the plant height (rice and weed), leaf number, or tiller per plant of Ischaemum rugosum when grown alone (I.R., R0) or in competition with a varying density of rice plants (R25, R50, or R100 kg ha−1).
Figure 3.
(a, b) Number of tillers per plant of Ischaemum rugosum (I.R.), rice seeding rates (R) when grown alone without rice (I.R., R0) or in competition with rice at different seeding rates (R), i.e., 25 (I.R., R25), 50 (I.R., R50), and 100 kg ha−1 (I.R., R100); and (c, d) number of tillers per plant under different nitrogen levels, i.e., 0 (I.R., N0), 50 (I.R., N50), 100 (I.R., N100), and 150 kg ha−1 (I.R., N150).
The vertical bars represent standard error of means. The lines represent a three-parameter sigmoid model (y = a/{1+e[−(x−x50)/b]}) fitted to the data. Parameter estimates are shown in Table 1.
Figure 4.
(a, b) Number of leaves per plant of Ischaemum rugosum (I.R.), rice seeding rates (R), when grown alone without rice (I.R., R0) or in competition with rice at different seeding rates (R), i.e., 25 (I.R., R25), 50 (I.R., R50), and 100 kg ha−1 (I.R., R100); and (c, d) number of leaves per plant when grown under different nitrogen levels, i.e., 0 (I.R., N0), 50 (I.R., N50), 100 (I.R., N100), and 150 kg ha−1 (I.R., N150).
The vertical bars represent standard error of means. The lines represent a three-parameter sigmoid model (y = a/{1+e[−(x−x50)/b]}) fitted to the data. Parameter estimates are shown in Table 1.
Figure 5.
(a, b) Leaf area of Ischaemum rugosum under different seeding rates and nitrogen levels.
The vertical bars represent standard error of means. The lines represent an exponential model fitted to the leaf area data. Parameter estimates are shown in Table 2.
Table 2.
The effect of different seeding rates and nitrogen levels on the leaf area of Ischaemum rugosum.
Figure 6.
(a, b) Leaf biomass, (c, d) stem biomass, and (e, f) inflorescence biomass of Ischaemum rugosum under different seeding rates and nitrogen levels.
The vertical bars represent standard error of means. (g) Stem biomass. The lines represent an exponential model fitted to the seedling biomass data.
Table 3.
The effect of different seeding rates and nitrogen levels on leaf, stem, inflorescence, and root biomass (g plant−1) of Ischaemum rugosum.
Figure 7.
(a, b) Shoot biomass, and (c, d) root biomass of Ischaemum rugosum under different seeding rates and nitrogen levels.
The vertical bars represent standard error of means. The lines represent an exponential model fitted to the seedling biomass data.
Table 4.
The effect of different seeding rates and nitrogen levels on aboveground shoot and root biomass (g plant−1) of Ischaemum rugosum.
Table 5.
Data on rice tillers per unit area (25 cm2); biomass of rice shoot, root, and total plant and root weight ratio (RWR) of the rice plant under different seeding rates, i.e., 0, 25, 50, or 100 kg ha−1; and under different nitrogen levels, i.e., 0, 50, 100, and 150 kg ha−1 for both experiments.
Figure 8.
Relationship between rice and Ischaemum rugosum biomass (g pot−1).
Figure 9.
(a, b) Leaf area ratio (LAR); (c, d) root-to-shoot weight ratio (RSWR); (e, f) leaf-weight ratio (LWR); and (g, h) specific leaf area (SLA) of Ischaemum rugosum under different seeding rates and nitrogen levels.
The vertical bars represent standard error of means.