Winter Wheat Photosynthesis and Grain Yield Responses to Spring Freeze

Detailed information on the growth dynamics, yield responses and soil water use of dual-purpose cereal crops after grazing is often required to devise guidelines for profitable grazing management. To increase the availability of such data, grazing experiments with winter wheat (Triticum aestivum) were conducted near Canberra, Australia. In 2007, cultivar Mackellar was grazed at low-short (LS, 33 sheep/ha for 31 days), heavy-short (HS, 67 sheep/ha for 31 days) or low-long (LL, 33 sheep/ha for 62 days) intensity-durations. In 2008, cultivars Mackellar and Naparoo were grazed at the HS intensity-duration. Aboveground net primary production (ANPP) of ungrazed Mackellar crops averaged 1181 g/m2. LS and HS grazing did not affect ANPP in 2007, but LL grazing in 2007 and HS grazing in 2008 treatments reduced ANPP by 20% (which included biomass removed by livestock). Average grain yield (381 g/m2) was not significantly affected by grazing. Grazing increased the proportion of water lost through soil evaporation but decreased transpiration, reducing shoot dry matter production per unit evapotranspiration by up to 22%. However, grazing did not affect grain yield per unit evapotranspiration. For rainfed wheat crops grown in temperate environments, greater biomass production occurred with shorter rather than longer grazing durations, irrespective of grazing intensities.

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Response of no-till winter wheat to seed-placed ammonium nitrate fertilizer

Canadian Journal of Soil Science ◽

10.4141/cjss91-005 ◽

1991 ◽

Vol 71 (1) ◽

pp. 55-66 ◽

Cited By ~ 3

Author(s):

D. B. Fowler ◽

J. Brydon

Keyword(s):

Winter Wheat ◽

Grain Yield ◽

Ammonium Nitrate ◽

Wide Band ◽

Winter Survival ◽

Grain Protein ◽

No Till ◽

Wide Range ◽

Nitrate Fertilizer ◽

Yield Responses

Winter wheat (Triticum aestivum L.) can be successfully overwintered in most regions of the Canadian prairies if it is sown without prior tillage into standing stubble immediately after harvest of the previous crop. Soil nitrogen (N) is usually deficient in this production system and N fertilization is necessary to optimize yield and maintain minimum quality standards. In the present study, the effect of seed-placed (SP), early-spring broadcast (BC), and SP/BC combinations of ammonium nitrate fertilizer (AN) on winter survival, grain yield and protein production of winter wheat was investigated in 15 field trials conducted over a wide range of soil types and environmental conditions in Saskatchewan. Ammonium nitrate fertilizer placed in a 20-mm-wide band with Norstar winter wheat seed produced average grain yield responses for 34, 67, and 101 kg N ha−1 treatments that were 98, 84, and 71% of comparable BC treatments, respectively. Average grain protein yield responses for the 34, 67, and 101 kg ha−1 SP N treatments were 94, 82, and 74% of comparable BC treatments, respectively. Grain protein concentration responses were similar for comparable BC and SP N treatments. Yield responses for 34 kg N ha−1 SP and BC treatments indicated that AN could be seed-placed at low rates without significantly reducing N-use efficiency. However, significant reductions in winter survival potential in all trials where differential winterkill occurred suggested that even rates as low as 34 kg N ha−1 SP AN should be avoided when cultivars with marginal winter hardiness are utilized. Key words: Winter wheat, no-till, seed-placed N, yield, protein, winter survival

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Effects of a spring-sown brassica crop on lamb performance and on subsequent establishment and grain yield of dual-purpose winter wheat and oat crops

Australian Journal of Experimental Agriculture ◽

10.1071/ea06152 ◽

2007 ◽

Vol 47 (7) ◽

pp. 815 ◽

Cited By ~ 27

Author(s):

W. M. Kelman ◽

H. Dove

Keyword(s):

Winter Wheat ◽

Grain Yield ◽

Nutritive Value ◽

Stem Elongation ◽

Kernel Weight ◽

Dual Purpose ◽

Brassica Crop ◽

Yield Responses

We evaluated the integration of a spring forage brassica crop (Brassica campestris cv. Hunter) into a cereal–pasture rotation, as a means of assessing the effects of this practice on the subsequent establishment and grain yield of wheat and oat crops. A brassica crop was grown for lamb production on 0.2 ha plots prepared for dual-purpose cereals, in spring 2003 near Canberra, ACT, Australia. Mackellar winter wheat and Blackbutt oats were sown in the following autumn on the previously sown brassica plots and on plots left fallow over the spring–summer period. A factorial experiment was used to determine the effects of (i) cultivar, (ii) brassica v. fallow, and (iii) grazing on cereal establishment and grain yield. Lamb liveweight gains on brassica over 33 days were rapid (294 g/day) and provided 2141 grazing days/ha and 637 kg lamb weight gain/ha. Average grain yield of Mackellar on plots following brassica (2.8 t/ha) was reduced by 29% compared with plots following fallow. Average grain yield on grazed plots (2.6 t/ha) was reduced by 38% compared with ungrazed plots. In both Mackellar and Blackbutt, reduced numbers of kernels per spike and reduced kernel weight accounted for the reduction in grain yield under grazing. Two other experiments were conducted at a separate site to obtain data on the nutritive value of the cereal forages and to record phenological development of the two cereals and compare grain yield responses to cutting before and after stem elongation stages. In vitro and in vivo measurements of digestibility in the vegetative phase were similar in the two cereals (91–94%). Grain yield was significantly reduced following cutting at the post stem elongation stage in Mackellar and Blackbutt and, in Mackellar, was attributable to reduced kernel number per spike and kernel weight. The overall economic return, combining actual returns from lamb production on the forage brassica, and estimated returns from grazing and grain production, after variable costs of each phase were accounted for, were $1117/ha for Mackellar wheat and $1081/ha for Blackbutt oats. These returns were $583/ha and $910/ha more than the estimated return from the fallow, ungrazed treatments for wheat and oats, respectively.

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