Performance of Some New White Maize Crosses under Water Stress Condition

Maize (Zea mays L.) is one of the most important food and fodder crops in Egypt and the world. In Egypt, the area of the maize in 2023 season was 3.2 million Fadden with total production 7.6 million ton  (Egypt State Information Service). Change of climate and water deficit were the tow problems for maize production. So, developing many crosses between new genotypes during 2020 season and investigated 2021 season to  found  maize hybrids tolerance for water stress.

According Ainer et al (1986) found that under water stress grain yield/feddan was decreased. Also, Ibrahim et al (1992) found that grain yield/feddan were significantly decreased with the increase of irrigation intervals (10, 14 and 18 days).However, Atta-Allah (1996) studied the effect of irrigation intervals (10, 15 and 20 days) on plant height, ear height and grain yield traits. He found that these traits were significantly increased with shorting irrigation interval. On the other hand,  Abdel-Mawgood et al (1999) studied the effect of three water regimes varying irrigation intervals (12, 16 and 20 days) on different traits. They found that the differences among the three water regimes were highly significant for days to 50% silking, plant height, ear height and grain yield per plant. Also, Oyekale et al (2008) stated that the usefulness of drought susceptibility index (DSI) for determining drought stress and suggest that maize hybrids with DSI values around 0.6 from field trials have potentials for satisfactory productivity under drought stress. Over and above, Karasu et al (2015) reported that, irrigation levels significantly affected the maize grain yield. However, Shankar et al  (2022) stated that, drought tolerant of hybrids can help maintain high maize productivity under limited water conditions. while, Shojaei et al (2022) state that, it can be possible through traditional breeding programs to achieve remarkable genetic progress in improving maize yield under conditions of water stress associated with high temperatures. as soon as, Khatibi et al (2022) reported that, the productivity of the maize crop depends largely on the amount of water available through the interval between the emergence of male and female inflorescences and up to a period of two weeks after the appearance of silks during this stage, the total number of grains in the plant is determined, water stress during that stage negatively effects the seed nodes, also the exposure of plants during the different stages of growth to severe water stress negatively effects plant height and ear height, and at the same time the increase in the number of days in which the formation of silk reaches 50% due to the lack of water. Planting dates are one of the important factors in maize cultivation. In Egypt maize is planted successfully from mid-April to mid-August, although most of the area is planted between May to mid-June as optimum period for production. All of,  El-Hosary (1988), Al-Ahmed et al (2004), Khallil et al (2013) and Abd El-Atyet al (2014) found significant differences between planting date and their interaction with genotypes for grain yield days to 50% silking, plant height and ear height.

The objective of this investigation is: to study the effects of planting date and water stress treatment on days to 50% silking, plant height, ear height and grain yield to identify the best genotypes under different planting date and irrigation treatments.

MATERIALS AND METHODS

Fifteen white inbred lines developed at Nubaria maize breading program, one white inbred line developed at Sids maize breeding program and two promising single crosses (SC 21 and SC 24) were randomly crossed to produce 21 white single crosses and two three-way crosses at Nubaria Agriculture Research Station to investigate tolerance for water stress at sids region in 2021 season. These 23 new hybrids in addition to four commercial hybrids (SC10, SC128, TWC321 and TWC324) were evaluated under two planting dates (15 May and 15 June) at Sids Agriculture Research Station in 2021 season. Split Split plot design with three replicates was used at each planting date. Two planting dates as main plot, two irrigation treatments as sub-plots; irrigation each 12 days (normal irrigation) and irrigation each 24 days (water stress),while the 27 hybrids were randomly allocated to the sub-sub-plots.

Plot size was one ridge 0.80 m apart, 0.25 m between hills with long 4 m. Two grains were planted per hill and later thinned to one plant. The recommended agronomic practices were done except irrigation treatments. The data were recorded for number of days from planting to mid-silking for each plot. Plant height was measured in (cm) from ground surface to flag leaf. Ear height was measured in (cm) from ground surface to ear leaf. Grain yield ardab/feddan(ard/fed) adjusted to 15.5% grain moisture.

The drought susceptibility index (DSI) was calculated only for grain yield per plant using a generalized formula according to Fischer and Maurer, (1978) as follows:

DSI= (1-Y_d/Y_p)/D

Low drought susceptibility index (DSI < 1) is synonymous with high drought stress tolerance.

Calculation of water requirements:

1. Reference Evapotranspiration (ET_o):

The reference evapotranspiration (ET_o) value using data from the agricultural weather station were available and the Penman-Monteith method was used in CROPWAT model (Smith, 1992), described by Allen et al. (1998) was used to calculate ET_o as follows:

Penman-Monteith Method: Penman-Monteith equation is given as:

Table 1.Agro-meteorological data and reference evapotranspiration values.

2.Crop Evapotranspiration (ETc):

The crop evapotranspiration (ETc) values were calculated according to equation of  Doorenbos and Pruitt (1977):

 4.Water productivity (WP):

Water productivity is generally defined as economical crop yield per cubic meter of applied water consumption. It was calculated according to Ali et al (2007).

 5.Yield response factor (Ky):

The Ky represents the relationship between relative evapotranspiration reduction and relative yield reduction   it was determined using the method given by Doorenbos and Kassam (1979). as follows:

Total water amount at normal irrigation treatment was about (2913 m³/fed) at first planting date, while it was about (1622 m³/fed) for the water stress treatment at the same planting date. The amount of irrigation water for normal treatment at second planting date was about (2647 m³/fed), while it was about (1454 m³/fed) for water stress treatment. The percentage of irrigation water saving was about 44% for first date and 45% for the second date (Table 2).

Irri= Irrigation, mm = Millimeter, fed =feddan

Statistical Analysis:

Split Split plot design with three replications was used at each planting date. Two planting dates was main plot, two irrigation treatments as sub-plots; irrigation each 12 days (normal irrigation) and irrigation each 24 days (water stress), while the 27 hybrids were randomly allocated to the sub-sub-plots. Homogeneity of error variance was found, therefore, the combined analysis over two planting date for the studied traits was done. The studied traits were analyzed using proc. Anova by SAS software version 9.1 (2008).

RESULTS AND DISCUSSION

The results on (Table 3), showed that significant or highly significant differences between two planting dates (D) were detected for days to 50% silking, plant height, ear height and grain yield. Also, highly significant differences values were observed of irrigation treatments (I) for grain yield, while the interaction between (D×I) was not significant for all studied traits. These results agreed with those of  Gheysari et al (2017) and El-Sabagh et al (2018). Significant or highly significant differences were observed for the tested hybrids (H) and their interactions (H×D),(H×I) and (H×D×I) for all studied traits except (H×D×I) for plant and ear heights. These results are in agreement with those of  El-Hosary (1988) and Abd El-Latifet al (2011).

Effects of planting dates on four studied traits are shown in (Table4), the means for plant height, ear height and grain yield were higher at mid-June than mid-May. While the reverse was obtained for days to 50% silking, meaning that the planting date at mid-June increased grain yield, plant height, ear height and earliness. El-Hosary (1988), Sedhom (1994) and Amer et al (2001) found that, planting dates differed for grain yield. Awad et al (1993) and Salem (1993) reported that planting in June gave the highest grain yield.

Table4. Effect of planting date on four studied traits.

Table (7). Effect of the interaction between hybrids and water treatment on grain yield (ardb/fed), Water productivity (WP), Yield response factor (KY) and drought susceptibility index (DSI).

N=(Normal irrigation), S=(Water stress), Nub=(Nubaria), SC=(Single Crosses), TWC=(Three Way Crosses).

In Table 8, the results showed that, the number of days to 50% silking, for all hybrids were earlier under normal irrigation compared with water stress condition, indicating that the water deficit delayed silk emergence. The hybrids ranged from 56.7 days for (Nub80×Nub65) to 67.5 days for (Nub71×Nub86)under (N) while ranged from 57.8 days for (Nub80×Nub65) to 68.5 days for (SC21×Nub86) under (S). The hybrids (Nub55×Nub68), (Nub77×Nub56), (Nub77×Nub86) and (Nub80×Nub65) were earlier than the best check SC128 under normal irrigation and water stress. The influence of hybrids by different irrigation treatments for days to 50% silking has been investigated by Meany researchers Song et al (2019), Abd-Elaziz et al (2020), Asrat (2021), Chukwudi et al (2022) and Saad-Allah et al (2022). For plant height, means of all hybrids under normal irrigation were higher than water stress condition. The shortest hybrid was (Sd10×Nub86) under (N) and (Nub76×Nub86) under (S).The selected single crosses (Nub68×Nub89), (Nub69×Nub76), (Nub86×Nub89) and (Sd10×Nub86) and the three-way cross (SC21×Nub86) had low means under (N) and (S). Influence on plant height of hybrids by irrigation treatments was obtained by many researchers Abd El-latif et al (2011), Aslam et al (2013), Rekaby et al (2017), Song et al (2019), Abd-Elaziz et al (2020), Chukwudi et al (2022) and Saad-Allah et al (2022). For ear height, the lower mean value was 105.8 cm for (Sd10×Nub86) under (N) and 95.9 cm for (SC21×Nub86) under (S), while the highest value was 131.7 cm for TWC 324 under (N) and 116.7 cm for (Nub72×Nub86) under (S). The selected new single crosses (Nub68×Nub89), (Nub73× Nub86) and (Sd10×Nub86) and new three-way cross (SC21×Nub86) had low values for ear height under (N) and(S).  These results are in agreement with Abd El-latiff et al (2011), Aslam et al (2013), Rekaby et al (2017), Song et al (2019), Abd-Elaziz et al (2020) and Saad-Allah et al (2022).From above results the selected hybrids can be used in breeding programs for earliness and plant density tolerant.

Table 8.Effect of the interaction between hybrids and irrigation treatments on days to 50% silking, plant height and ear height.