Grain Yield Of Plants Research Articles

PERFORMANCE OF OAT PLANTS GROWN FROM PRIMARY AND SECONDARY KERNELS

Mixtures of primary and secondary kernels within each of four oat (Avena sativa L.) genotypes differing in primary:secondary kernel weight ratio (weight of primary kernels/weight of an equal number of secondary kernels) were grown in four environments with diverse yield levels. Grain and straw yields and numbers of panicles per plant and spikelets per panicle decreased as the frequency of secondary kernels in the primary:secondary combinations increased, while 100-kernel weight was relatively constant. The reductions that occurred as the proportion of secondary kernels increased were linear and were not affected by genotype, environment, or genotype × environment interaction. Plants in plots grown from 100% primary kernels yielded 14.5% more grain and 13.1% more straw than plants in plots grown from 100% secondary kernels. The higher grain yields of plants grown from primary kernels were due to comparable increases in tillering and spikelets per panicle. Although our results indicate that grain and straw yields can be increased significantly by separating out at least one half of the secondary kernels in seed oats, the cost of separating should be compared to the anticipated monetary gain from grain and straw yield improvements to determine if the extra handling would be an economically sound practice.

The epidemiology of common root rot in Manitou wheat. IV. Appraisal of biomass and grain yield in naturally infected crops

The effects of common root rot (Cochliobolus sativus) on plant biomass and grain yield in naturally infected Triticum aestivum cultivar Manitou were studied at Matador, Saskatchewan, by sampling plants at intervals from seeding to maturity in 1969, 1970, and 1971. Plants were categorized according to the extent of subcrown internode lesions as clean, slight, moderate, or severe. Dry weights and grain yields of plants in each category were determined. Decreasing mean dry weight per plant at all dates and grain yield per plant were consistently associated with increasing disease severity. Significant differences in biomass and grain yield generally existed between clean and slight, slight and severe, and moderate and severe categories. Very close relationships existed between losses in biomass and grain yield both per plant and per unit area. Overall mean biomass losses at maturity in severe, moderate, and slight plants as compared with clean were 58%, 37%, and 25%, respectively; losses in grain yield were 59%, 38%, and 26%, respectively. Biomass losses per square metre increased steadily with time, in all treatments. Grain yield losses per square metre for 1969, 1970, and 1971 summer-fallow checks were 30, 35, and 30%, respectively; the biomass losses at the final sampling dates were analogous.

Physiological Causes of Differences in Grain Yield between Varieties of Barley

In a field experiment on barley at Rothamsted with the high mean yield of 49 cwt. of grain per acre, the varieties Proctor and Herta produced 10—15 per cent, more grain than Plumage-Archer on plots that received no nitrogenous fertilizer. When nitrogen was applied the difference was increased to about 30 per cent., because the higher nitrogen supply caused the Plumage-Archer crop to lodge and did not increase its yield, while Proctor and Herta remained standing. The three varieties did not differ in leaf-area index nor in net assimilation rate before ear emergence, so that all had the same total dry weight. After ear emergence, the leaf-area indices of Proctor and Plumage-Archer were nearly equal, but that of Herta was smaller. Assuming that the photosynthetic efficiency of the leaves continued to be the same in all varieties, the higher grain yields of Proctor and Herta cannot be attributed to greater production of dry matter by the leaves, either before or after ear emergence. A pot experiment on plants with shaded ears confirmed that the dry matter contributed to grain yield by unit leaf area was nearly equal in all the varieties. The higher grain yield of Proctor and Herta than of Plumage-Archer must therefore have come from additional photosynthesis in parts of the plant other than the leaves, i.e. in the ears themselves. An attempt to demonstrate this directly in a pot experiment, by comparing the grain yields of plants with shaded or with unshaded ears, was unsuccessful because the varieties behaved differently in pots; Proctor and Herta produced only about 6 per cent, more grain yield than Plumage-Archer, and though the decrease in grain yield by shading the ears was slightly greater for Proctor and Herta, the differences were not significant. The sum of ear sizes (estimated from length and breadth measurements) per m.1 in the field experiment was greater for Proctor and Herta than for Plumage-Archer. Also the distribution of dry matter between developing ears and shoots apparently differed with variety, so that at ear emergence the dry weight of ears per m.2 was greater in the two higher yielding varieties. The increased amount of photosynthetic tissue in the ears of Proctor and Herta, as measured by size or weight, may not wholly explain their greater dry-matter production; ears of Herta may also have a higher photosynthetic efficiency. No differences in nutrient uptake that could account for the varietal differences in grain yield were found. Plumage-Archer absorbed more potassium, and Herta less phosphorus than the other varieties. About a quarter of the final content of nitrogen, and a third of the phosphorus, was absorbed after ear emergence, but the potassium content was nearly maximal at ear emergence and later decreased. The pot experiment showed that, on the average of all varieties, 26 per cent. of the dry matter in the grain at harvest originated from photosynthesis in the ears, including 10 per cent, from the awns; 59 per cent, came from photosynthesis in the flag-leaf lamina and sheath and peduncle, and 15 per cent, from parts of the shoot below the flag leaf.