The transpiration of corn

Abstract

The actual transpiration of corn (Zea mays L.) was determined by hydraulic lysimeters, by the inflow-outflow method and by use of a neutrone probe. Two irrigation treatments were used; wet and dry. Under the wet treatment, 740, 858, and 743 mm of irrigation water was used during the seasons 1968, 1969, and 1970 respectively. Under the dry treatment, amount of irrigation water used was 560, 627, and 565 mm during the seasons 1968, 1969 and 1970, respectively. Ratios of actual transpiration (Et) to Penman's estimate of potential evaporation (Eo), evaporation from a Class-B pan (EpB), global radiation (Rg) and net radiation (Rn) were calculated. Values of Et measured by the different methods are in good agreement. Seasonal averages of Et , were 6-2 and 4-9 mm/day under wet and dry treatments, respectively. The Et/Eo, Et/EpB, Et/Rg and Et/Rn ratios increased with leaf area index (L.A.I.) and reached their maximum values when L.A.I, reached its maximum value of 1-03 under wet and 0-92 under dry treatment. The empirical coefficient (/ = Et/Eo) under wet treatments was found to be higher than that given by Penman for short grasses and about the same as that obtained by Boumans et al. (1963) for golden-gram (Phaseolus aureus) in Iraq for the months August and September. The empirical coefficient Kb in the BlaneyCriddle formula was greater than the value given by Blaney and Criddle for an arid climate, and less than the value obtained by Boumans et al. for golden-gram in Iraq. It was further found that water use efficiency for grain production was greater under dry than under wet treatments.

Drought and Maize Breeding

“…Numerous studies have been done in Iraq in the last three decades on the water consumption of maize. The water consumption of this crop (autumnal loop) in central Iraq was estimated at 605 to 740 mm under dry and wet treatments [35]. The water consumption of maize was studied at the Abu Ghraib Experimental Station and the results were for wet and dry treatments (740, 855 and 743 mm) and (605, 693 and 567 mm), respectively for the years 1968, 1969 and 1970 [36].…”

The transpiration of Mexipak wheat (Triticum aestiviumL.) in central Iraq

“…type tensiometer placed at a depth of 40 cm below Description of the soil, the lysimeters, the weather the soil surface. station, calculation of net radiation (Rn), Penman Actual transpiration was measured by the inflowestimate of potential evaporation (Eo) and the outflow method in the lysimeters for the seasons determination of the coefficient Kb were given by 1969, 1971, 1972and 1973. During the 1969season, Al-Nakshabandi & Ismail (1972.…”