Growth, mineral composition and digestibility of maize, sorghum and barnyard millets at different temperatures

Abstract

Barnyard millets (Echinochloa utilis and E. frumentacea), maize (Zea mays) and a sorghum hybrid (Sorghum bicolor x S. sudanense) were grown as spaced plants at temperature regimens from 15/10 to 33/28�C (dayhight). Leaf and stem dry weight, leaf area and leaf number were recorded every 2 weeks and the dry matter analysed for nitrogen, sulfur, sodium and in vitro digestibility. Tolerance to low temperatures was in the order maize > E. utilis >sorghum >E. frumentacea. At mean temperatures above 25�C, relative growth rates were similar for all species. Differences in leaf area, for which individual leaf size was mainly responsible, accounted for most of the dry weight responses to temperature, although net assimilation rate responses were also apparent. The dry weight response to temperature became negligible after adjusting for differences in stage of development. Dry matter digestibility decreased with temperature; it also decreased with time because of deteriorating stems, except in sorghum. Maize leaves were of low digestibility, similar to stems. The nitrogen : sulfur ratio of all species remained steady with age; in sorghum at low temperature it exceeded the 15: 1 maximum considered desirable for animals. Sodium was highest in E. utilis stems and increased with temperature, in contrast to sorghum. Maize had a marginal nitrogen: sulfur ratio and unacceptably low sodium concentration. It was concluded that more attention should be given to E. utilis as a forage for cool climates.

Micronutrients (Zn/Mn), seaweed extracts, and plant growth-promoting bacteria as cold-stress protectants in maize

“…This study was designed to compare the efficiency of different mitigation strategies against low root zone temperatures during early growth as a major constraint for maize cultivation in temperate climates [1][2][3][4], including supplementation of critical micronutrients (Zn, Mn) [14], application of seaweed extracts [15], and inoculation with plant growth-promoting and cold-tolerant bacteria [16]. Surprisingly, despite a proven plant growth-promoting potential [24,25] even in combination with the tested maize cultivar [26,27], the investigated microbial inoculants, including a psychrotolerant strain of Bacillus simplex, failed to show any beneficial effects on growth of maize seedlings exposed to moderately low RZT of 12-14 °C.…”

“…However, for plant species like maize with optimum temperatures of 25-30 °C for germination and plant growth [1,2], even moderately low soil temperatures <15 °C are already detrimental to root development, fine root branching, and root elongation [3,4]. Apart from root growth, also root activity in terms of nutrient uptake and nutrient translocation, adaptive root exudation for nutrient mobilization [5], and hormonal balances are impaired by low root zone temperatures (RZT), [6,7].…”

Nutrient seed priming improves seedling development of maize exposed to low root zone temperatures during early growth

“…Temperature between 25 • C and 30 • C is optimal for maize growth, i.e. germination, shoot and root growth, leaf development and expansion (Miedema et al, 1987;Duncan and Hesketh, 1968;Muldoon et al, 1984). Foyer et al (2002) discussed limited capacity of maize plants to acclimatize to low temperature during early growth.…”

Synergisms of Microbial Consortia, N Forms, and Micronutrients Alleviate Oxidative Damage and Stimulate Hormonal Cold Stress Adaptations in Maize

“…As a consequence of cold stress (5−15 • C), poor field establishment due to inhibition of root development, impaired uptake and translocation of water and nutrients can translate into poor vegetative growth, low-stress resistance and finally reduction of yield (Duncan and Hesketh, 1968;Muldoon et al, 1984;Imran et al, 2013). Besides, the maize shoot meristem is directly affected since it remains belowground even until the V6 stage (Stone et al, 1999).…”