Abstract: Drought risk is considered to be among the main limiting factors for maize (Zea mays L.) production in the Northeast Farming Region of China (NFR). Maize yield data from 44 stations over the period 1961-2010 were combined with data from weather stations to evaluate the effects of climatic factors, drought risk and irrigation requirement on rain-fed maize yield in specific maize growth phases. The maize growing season was divided into four growth phases comprising seeding, vegetative, flowering and maturity based on observations of phenological data from 1981 to 2010. The dual crop coefficient was used to calculate crop evapotranspiration and soil water balance during the maize growing season. The effects of mean temperature, solar radiation, effective rainfall, water deficit, drought stress days, actual crop evapotranspiration and irrigation requirement in different growth phases were included in the statistical model to predict maize yield. During the period 1961-2010, mean temperature increased significantly in all growth phases in NFR, while solar radiation decreased significantly in southern NFR in the seeding, vegetative and flowering phases. Effective rainfall increased in the seeding and vegetative phases, reducing water deficit over the period, whereas decreasing effective rainfall over time in the flowering and maturity phases enhanced water deficit. An increase in days with drought stress was concentrated in western NFR, with larger volumes of irrigation needed to compensate for increased dryness. The present results indicate that higher mean temperature in the seeding and maturity phases was beneficial for maize yield, whereas excessive rainfall would damage maize yield, in particular in the seeding and flowering phases. Drought stress in any growth stage was found to reduce maize yield and water deficit was slightly better than other indicators of drought stress for explaining yield variability. The effect of drought stress was particularly strong in the seeding and flowering phases, indicating that these periods should be given priority for irrigation. The yield-reducing effects of both drought and intense rainfall illustrate the importance of further development of irrigation and drainage systems for ensuring the stability of maize production in NFR.

Abstract: A field experiment was carried out in southern Italy to investigate the effects of irrigation and salinity on a maize crop and soil properties. The experiment was laid out comparing different irrigation rates (I1, I2, I3—re-establishing 50, 75 and 100% of the calculated maximum evapotranspiration) and water quality (FW, fresh water and SW, saline water). Grain yield was significantly greater by 60% in 2008 than in 2010. No significant difference was shown for grain yield between the irrigation treatments, whereas water productivity decreased significantly with increasing irrigation rates. Irrigation with saline water did not significantly reduce grain yield compared with fresh water, but it improved grain quality with higher protein content (9.1%) and lower grain moisture percentage (13.3%). Saline water determined a significant increase of saturated soil paste extract Na, ECe, SAR, some exchangeable cations and ESP compared with FW in both years. Furthermore, at the end of the experiment these parameters were lower than those at the end of the first maize crop. Lastly, in the saline treatment, at the end of the trial, the ECe and ESP values were below the critical threshold for soil salinization and/or sodification.