Waterlogging is one of the limiting factors influencing durum wheat (Triticum durum L.) production. In this paper we investigated the impact of seven waterlogging durations of 4, 8, 12, 16, 20, 40, and 60 days, imposed at 3-leaf and 4-leaf growth stages, on grain yield, grain yield components, straw and root dry weight and nitrogen concentration of grain, straw, and roots of two varieties of durum wheat. Grain yield of both varieties showed a significant reduction only when waterlogging was prolonged to more than 20 days, and 40-d and 60-d waterlogging reduced grain yield by 19% and 30%. Waterlogging depressed grain yield preventing many culms from producing spikes. It slowed down spikelet formation, consequently reducing the number of spikelets per spike, and reduced floret formation per spikelet, thus reducing the number of kernels per spike.

SUMMARY: Legume crops are not usually fertilised with mineral N. However, there are at least two agronomic cases when it would be advantageous to distribute N fertiliser to legume crops: at sowing, before the onset of nodule functioning, and when a legume is intercropped with a cereal. We highlight the impact of various levels of fertiliser nitrogen on grain yield, nodulation capacity and biological nitrogen fixation in the four most common grain legume crops grown in central Italy. Chickpea (Cicer arietinum L.), field bean (Vicia faba L. var. minor), pea (Pisum sativum L.) and white lupin (Lupinus albus L.) were grown in soil inside growth boxes for two cropping seasons with five nitrogen fertilisation rates: 0, 40, 80, 120 and 160 kg ha⁻¹. In both years, experimental treatments (five crops and five levels of N) were arranged in a randomised block design. We found that unfertilised plants overall yielded grain, total biomass and nitrogen at a similar level to plants supplied with 80–120 kg ha⁻¹ of mineral nitrogen. However, above those N rates, the production of chickpea, pea and white lupin decreased, thus indicating that the high supply of N fertiliser decreased the level of N₂ fixed to such an extent that the full N₂-fixing potential might not be achieved. In all four grain legumes, the amount of N₂ fixed was positively related to nodule biomass, which was inversely related to the rate of the N fertiliser applied. The four grain legumes studied responded differently to N fertilisation: in white lupin and chickpea, the amount of nitrogen derived from N₂ fixation linearly decreased with increasing N supply as a result of a reduction in nodulation and N₂ fixed per unit mass of nodules. Conversely, in field bean and pea, the decrease in N₂ fixation was only due to a reduction in nodule biomass since nodule fixation activity increased with N supply. Our results suggest that the legume species and the N rate are critical factors in determining symbiotic N₂-fixation responses to N fertilisation.

In Mediterranean Europe, winter cereals can experience soil waterlogging starting from crop establishment up to stem elongation and, in late sowings, this stress is combined with temperatures favorable to plant metabolism. Oats response to waterlogging has been rarely investigated, but these species seems to recover better than other cereals. In a 2-year experiment, Avena sativa and Avena byzantina were sown at the end of winter in pots placed outdoors. At the two-tiller stage, plants were exposed to waterlogging for periods ranging from 0 to 35 days. The dry weight and the N-concentration of shoots and roots were determined on waterlogged plants and drained controls at the start and the end of each waterlogging period, and at maturity. At maturity, the grain yield and its components were determined. To relate oat response to its specific morphological and developmental traits, results were compared to the published results in wheat and barley. Both oat species suffered severe damage during waterlogging: the uptake of nitrogen and the N-concentration of shoots were reduced after 7 days, tiller initiation and root growth after 14 days, and shoot growth after 21 days. All plants survived waterlogging, and the relative growth rates of roots and shoots and the net uptake rate of nitrogen were resumed during recovery. Nevertheless, at maturity, the straw and root biomass were markedly lower with all waterlogging durations, and grain yield decreased by 42% up to approximately 81% following an asymptotic equation. The most affected yield components were the number of panicles per plant and the number of kernels per panicle, but their relative sensitivity changed according to waterlogging duration. The slight increase in tiller fertility in response to short waterlogging and the small and irregular decrease in the number of kernels per spikelet suggest that the two oats could recover the initiation and size of inflorescences better than other winter cereals. Despite this, waterlogging in spring was highly detrimental to these oats because of severe damage under waterlogging and because of the inability to initiate new tillers and adequately resume root growth during recovery, once plants had achieved the phase of stem elongation.

Soil flooding and submergence, collectively termed waterlogging, are major abiotic stresses that severely constrain crop growth and productivity in many regions. Cool-season grain legumes can be exposed to submersion both at the vegetative and reproductive stages. Limited research has been carried out on these crops with waterlogging imposed at flowering. We evaluated how waterlogging periods of 0, 5, 10, 15, and 20 d at flowering affected seed yield, biomass of shoots, roots and nodules, and N uptake of faba bean (Vicia faba L. var. minor), pea (Pisum sativum L.), and white lupin (Lupinus albus L.). Faba bean tolerated submersion better than pea and white lupin. Pea and white lupin plants did not survive 10 d of submersion, and after 5 d the seed yield, shoot and root biomass, and N uptake had more than halved. Faba bean survived 20 d of waterlogging, although seed and biomass production and total N uptake were severely reduced. Shoot dry weight and seed yield decreased linearly with the duration of waterlogging, which negatively affected seed more than the vegetative plant part weight. In all three crops waterlogging at flowering led to damage, which could not be recovered during seed filling.

Waterlogging stress is one of the limiting factors influencing wheat (Triticum aestivum L.) production. Wheat tolerance to waterlogging is related to the duration of the waterlogging event, the crop development stage in which waterlogging occurs, and the sensitivity of genotype. In this paper we investigated the impact of eight waterlogging durations (from 0 to 60 days) imposed at 3-leaf and 4-leaf growth stages (~30 and 40 days after sowing) on grain yield, grain yield components, straw and root dry weight and nitrogen concentration of grain, straw, and roots of two cultivars of wheat. The results showed that of the two cultivars, one (cv. Blasco) was tolerant to waterlogging and the other (cv. Aquilante) was sensitive, thus confirming that there are high genotypic differences in terms of tolerance to waterlogging in wheat. The sensitive cultivar showed a significant reduction in grain yield and straw and root dry weight only when waterlogging was prolonged for more than 20 days. Waterlogging depressed the grain yield of the sensitive cultivar, slowing tiller formation and consequently preventing many culms from producing spikes. It slowed down spikelet formation, consequently reducing the number of spikelets per spike, and reduced floret formation per spikelet, thus reducing the number of kernels per spike.