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The objective of the present study was to investigate the interactive effects of foliar fertilization and drought and salinity on the growth of maize. Maize plants were grown in soil under drought or salinity in a greenhouse for 23 days after sowing. At harvest, plant height, shoot biomass, and the lengths, fresh weights and dry weights of the blade in the expanded leaf 3 and expanding leaves 4 and 5 were determined. Mineral elements (Na, K, Ca, Mg, P and N) in individual leaves were analyzed. Although there was a reduction in evapotranspiration, maize growth, such as shoot fresh weight and dry weight, and leaf fresh weight and dry weight under drought and salinity, the application of foliar fertilization did not improve plant growth under short-term drought or salt stress. Drought reduced the uptake of K, Ca, Mg and P, which may be attributed to decreased transpiration. An increase or no change in the nutrient concentration in leaves under saline conditions suggests that an osmotic effect may be responsible for the plant reduction.

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The yield response of forage maize (Zea mays L.) genotypes to plant density is not as clear as for grain hybrids, where density tolerant and sensitive types have been identified. A study including field trials, laboratory analyses, and in situ digestibility tests with one density‐tolerant and one sensitive hybrid was conducted with plant densities of 4 to 16 plants m−2. The investigations concentrated on stover. There are differences in sensitivity to planting density in forage maize yield. Differences between sensitive and tolerant genotypes in plant density range for maximum yield were 0.43 and 1.18 plants m−2 for grain and forage, respectively. The decreased sensitivity for grain compared with forage was 50.7 and 100.0% for the sensitive and the tolerant hybrid, respectively. It was not possible to separate the tolerant and sensitive hybrids in terms of total digestible nutrients (TDN), a measure of overall feed value. For plant densities lower than those required for maximum dry matter yield, there was a significant difference between the tolerant and the sensitive hybrid in TDN.

The aim of this work was to test the sensitivity of the water potential (Ψw), osmotic potential (Ψs) and turgor (Ψp) of roots and leaves of maize seedlings (Zea mays L. cv. Carla) subjected to a mild stress in drying soil in a growth chamber. To the best of our knowledge there are no experimental data which describes diurnal courses of Ψw in soil, roots, and leaves and the parallel changes in the osmotic potential (Ψs) and turgor (Ψp) of roots and leaves from plants grown in moist and drying soil. Root and leaf Ψw varied diurnally, the amplitude being much more marked in leaves than in roots. Root and leaf Ψw did not achieve equilibrium at predawn with the bulk soil matric potential (Ψm) but became higher. Our results are at variance with data indicating root Ψw is a sensitive indicator of soil dryness. Root Ψw in the well-watered and drought-stressed treatments did not differ, whereas daytime leaf Ψw in the droughted treatment was lower 6 days after water was withheld. Diurnal changes in Ψs and Ψp were more marked in leaves than in roots. Withholding water lowered leaf Yp, whereas root Ψp substantially increased after only 3 days of withholding water. Early mild stress can be more easily and more quickly identified by changes in root Ψs, increases in root Ψp, or the divergence in root and leaf Ψp than by a lower Ψw of root or leaf. Relative water contents of roots and leaves measured in the light period indicated also sensitively falling Ψm.

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Opaque‐2 (o2) maize (Zea mays L.) contributed significantly to the quality improvement of maize breeding in the 1960s, but did not become popular because of a lower yield, a result of its shorter grain‐filling period. This characteristic, however, could prove to be advantageous for use in corn cob mix (CCM), which is popular in the cold‐wet regions of Europe. A research program including a 3‐yr field trial, an in vivo pig (Sus scrofa) study with fermented CCM, and a farm‐scale fattening test was conducted to evaluate the prospect of o2 for CCM production and utilization. Opaque‐2 yielded as much CCM at the CCM ripening stage (600 g kg−1 grain DM) as did the normal version. Due to its shorter grain‐filling period, 02 can accumulate more assimilates at a higher grain moisture content than the normal maize. Results from in vivo pig trials showed that o2 was superior in N retention and in the biological value of protein compared with the normal genotype. Consequently, using o2 can balance the feed value and reduce the soybean [Glycine max (L.) Merr.] content in the ration for fattening pigs by 27%. The quality of the meat of slaughtered pigs fed with o2 and less soybean was comparable to that of pigs fed with normal maize and larger supplement of soybean protein. Improved o2 genotypes may be an alternative source of CCM production in countries where the climate is not very favorable for soybean production and where alternative protein supplements are not readily available.

The effect of natural and artificial hail on the evapotranspiration of maize (Zea mays L.) was studied. In 1998, observations were made after a natural hailstorm, while in 1999 hail was simulated by lacerating the leaves parallel with the leaf veins. Plants of one treatment were grown in a lysimeter. In addition to evapotranspiration, measurements were also made on plant temperature. Among physiological processes, the modifications occurring in evapotranspiration could be divided into two distinct phases. On the days immediately following the damage the raised plant temperature caused by the wounds indicated a reduction in evapotranspiration leading to less efficient plant cooling. Later, in both the natural and artificial hail treatments, changes in evapotranspiration depended on the weather. The changes in evapotranspiration and plant temperature after natural and artificial hail injury were similar in nature. The yield loss was less than 10 %, in agreement with data in the literature on the effect of simulated hail injury. However, it can be expected that further study of simulated hail injuries will lead to a better understanding of the changes in plant water balance caused by hail.