Agronomic and physiological response of maize (Zea mays L.) hybrids to plant density in the dry and wet Middleveld of Eswatini

S.C. Malaza and T. Tana*

Department of Crop Production, University of Eswatini, P. O Luyengo, M 205, Eswatini
*Correspondence: tamado@uniswa.sz

Abstract:

One of the factors limiting yield of maize in Eswatini is use of non-optimum plant density for the different maturity group of maize hybrids in different agro-ecologies. Thus, an experiment was conducted at Malkerns (wet Middleveld) and Luve (dry Middleveld) in Eswatini to determine the effects of plant density on growth, yield components and grain yield of maize hybrids. Factorial combinations of three maize hybrids [SC 403 (early maturing), SC 621 (medium maturing), SC 719 (late maturing)] and five plant densities (41,667; 44,444; 47,619; 50,000, and 57,143 plants ha^-1) were evaluated in Randomised Complete Block Design in three replications. The results showed that Malkerns had significantly higher crop growth rate (CGR) between V12 and R6 growth stages, relative growth rate (RGR) between V6 and V12 growth stages, mass of thousand kernels (395.60 g), aboveground dry biomass (22.71 t ha^-1) and grain yield (7.67 t ha^-1). Among maize hybrids, SC 719 produced significantly the highest CGR (18.37 g m^-2 per day) between V12 and R6, aboveground dry biomass (23.05 t ha^-1), number of kernels per m² (2074), and grain yield (7.49 ha^-1). Moreover, SC 719 grown at Malkerns recorded significantly the highest leaf area index (LAI) at V6, and the highest CGR (31.35 g m^-2 per day) between V6 and V12 and the tallest plants. The highest density of 57,143 plants ha^-1 produced the highest LAI, aboveground dry biomass (21.53 t ha^-1) and grain yield (7.17 t ha^-1). Thus, late maturing maize hybrid SC 719 and plant density of 57,143 plants ha^-1 (70 cm × 25 cm) can be used to enhance the productivity of maize in the Middleveld of Eswatini.

Key words:

Dynamics of tuber weight in early potato varieties in the contrasting weather conditions of the Northwestern Russia

L.Yu. Novikova¹*, N.A. Chalaya¹, M.N. Sitnikov¹, L.M. Gorlova¹, S.D. Kiru² and E.V. Rogozina¹

¹N.I. Vavilov All-Russian Institute of Plant Genetic Resources (VIR), 42, 44, Bolshaya Morskaya Str., RU190000 St. Petersburg, Russia
²St. Petersburg State Agrarian University, Building A, 2, Peterburgskoe shosse, Pushkin, RU196601 St. Petersburg, Russia
*Correspondence: l.novikova@vir.nw.ru

Abstract:

Under climate changes, it is particularly important to search for characteristics of varieties that are steady in contrasting weather conditions. The aim of the present research was to study the relationship between the growth of tubers and haulms in early potato varieties in the Northwestern Russia. Fourteen early potato varieties were studied in the field experiments conducted in 2017–2019 in the vicinities of St. Petersburg. The results of three intermediate digs on the 45^th, 60^th and 75^th day from the planting date were analyzed. The correlation analysis, ANOVA, and regression were used. The average haulm and tubers weight significantly differed in the years of the study, while the number of tubers per plant and the haulm to tubers weight ratio did not differ. The relative growth rate of tubers weight from day 45 to 60 and from 60 to 75 did not differ significantly between 2018 and 2019, the years contrasting in terms of weather conditions. On the average, the tubers weight increased 2.6–2.8 times from day 45 to 60, and 1.4 times from day 60 to 75. It has been established that the early prediction of productivity in early potato varieties can be based on the haulm weight on the 60^th day after planting; its coefficient of correlation with productivity was 0.72–0.79. Every 100 grams of the haulm weight on day 60 ensures a 100–200 g increment in the tubers weight by the time of harvest on day 80. The obtained results can be used in the development of a morphometric indicator-based automated system for monitoring the growth of potato plants.

Key words:

biometric indicators, dynamics, potato, productivity, relative growth rate