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Ear Position, Leaf Area, and Contribution of Individual Leaves to Grain Yield in Conventional and Leafy Maize Hybrids

Agriculture and Agri-Food Canada, Eastern Cereal and Oilseed Research Centre (ECORC), Central Experimental Farm, 960 Carling Avenue, Ottawa, ON, Canada K1A 0C6

View larger version (30K): [in a new window]   Fig. 1. Total precipitation (mm) and mean air temperatures (°C) in 10-d intervals during 2003 and 2004 growing seasons at the experimental site at Ottawa.

View larger version (30K): [in a new window]   Fig. 2. Green leaf area (cm2 plant–1) of the removed leaf or leaves in different leaf removal treatments as compared with the control treatment (T1) at silking stage of a conventional (Pioneer 3893) and Leafy (Maizex LF850 RR) maize hybrid in 2003 and 2004. The sum of leaf areas below the earleaf, above the earleaf, and earleaf makes total leaf area of a plant. The ± error bars are the standard deviations of eight plants. The leaf removal treatments are: T1, no leaf removal (control); T2, all leaves below the earleaf removed; T3, all leaves above the earleaf removed; T4, earleaf removed; T5, earleaf + 1 removed; T6, earleaf + 2 removed; T7, earleaf + 3 removed; T8, earleaf + 4 removed; T9, earleaf + 5 removed, and T10, earleaf + 6 + all other leaves removed.

View larger version (40K): [in a new window]   Fig. 3. Final leaf area index (LAI) after different leaf removal treatments at silking stage of a conventional (Pioneer 3893) and Leafy (Maizex LF850 RR) maize hybrid in 2003 and 2004. The ± error bars are the standard deviations. The leaf removal treatments are: T1, no leaf removal (control); T2, all leaves below the earleaf removed; T3, all leaves above the earleaf removed; T4, earleaf removed; T5, earleaf + 1 removed; T6, earleaf + 2 removed; T7, earleaf + 3 removed; T8, earleaf + 4 removed; T9, earleaf + 5 removed, and T10, earleaf + 6 + all other leaves removed.

View larger version (30K): [in a new window]   Fig. 4. Leaf dry matter (g plant–1) of the removed leaf or leaves in different leaf removal treatments as compared with the control treatment (T1) at silking stage of a conventional (Pioneer 3893) and Leafy (Maizex LF850 RR) maize hybrid in 2003 and 2004. The ± error bars are the standard deviations. The leaf removal treatments are: T1, no leaf removal (control); T2, all leaves below the earleaf removed; T3, all leaves above the earleaf removed; T4, earleaf removed; T5, earleaf + 1 removed; T6, earleaf + 2 removed; T7, earleaf + 3 removed; T8, earleaf + 4 removed; T9, earleaf + 5 removed, and T10, earleaf + 6 + all other leaves removed. Leaf dry matters per plant of the control plants were 28.2 g and 27.7 g for Pioneer 3893 and 39.3 g and 38.1 g for Maizex LF850 RR, respectively in 2003 and 2004.

View larger version (119K): [in a new window]   Fig. 5. Ears of maize from one of the blocks at harvest: Pioneer 3893 (upper row) and Maizex LF 850 (lower row) as affected by different leaf removal treatments (T1, no leaf removal; T2, all leaves below the earleaf removed; T3, all leaves above the earleaf removed; T4, earleaf removed; T5, earleaf + 1 removed; T6, earleaf + 2 removed; T7, earleaf + 3 removed; T8, earleaf + 4 removed; T9, earleaf + 5 removed, and T10, earleaf + 6 + all other leaves removed). The Pioneer 3893, was limited up to T9.

View larger version (41K): [in a new window]   Fig. 6. Effect of different leaf removal treatments on the number of kernels per ear in Pioneer 3893 and Maizex LF850 RR maize hybrids in 2003 and 2004. The leaf removal treatments are: T1, no leaf removal; T2, all leaves below the earleaf removed; T3, all leaves above the earleaf removed; T4, earleaf removed; T5, earleaf + 1 removed; T6, earleaf + 2 removed; T7, earleaf + 3 removed; T8, earleaf + 4 removed; T9, earleaf + 5 removed, and T10, earleaf + 6 + all other leaves removed. The Pioneer 3893 was limited up to T9. The bars with the same letter in each hybrid are not significantly different by LSD0.05 test.

View larger version (44K): [in a new window]   Fig. 7. Effect of different leaf removal treatments on the kernel dry matter in Pioneer 3893 and Maizex LF850 RR maize hybrids in 2003 and 2004. The leaf removal treatments are: T1, no leaf removal; T2, all leaves below the earleaf removed; T3, all leaves above the earleaf removed; T4, earleaf removed; T5, earleaf + 1 removed; T6, earleaf + 2 removed; T7, earleaf + 3 removed; T8, earleaf + 4 removed; T9, earleaf + 5 removed, and T10, earleaf + 6 + all other leaves removed. The Pioneer 3893 was limited up to T9. The bars with the same letter in each hybrid are not significantly different by LSD0.05 test.

View larger version (26K): [in a new window]   Fig. 8. Relationships between percentage of leaf area removed and percentage reduction in grain yield (kernel DM) in the two hybrids of maize in two years. The bold line is the linear fit for the Maizex LF 850 RR while the thin line is for the Pioneer 3893.

View larger version (17K): [in a new window]   Fig. 9. Differences in SPAD readings in the earleaf of two maize hybrids (Pioneer 3893 and Maizex LF850 RR) as affected by the stage of crop development (R1, R2, and R4 growth stages) in 2004. The vertical bars are the LSD0.05 values to separate the two hybrids at each growth stage.