Effects of abiotic factors on fulfillment of the potential of pea cultivars

Abstract

The aim and tasks of the study was to evaluate the effects of the abiotic factors (temperature regime and precipitation amount) on the yield and protein content in seeds of pea cultivars.

Materials and methods. The experiments were carried out in the experimental field of the Plant Production Institute named after VYa Yuriev (PPI nd. a. VYa Yuriev) in 2008–2017 by the field experimentation techniques. Twenty six pea cultivars were studied; of them 19 were created in the Laboratory of Pea Breeding of the PPI nd. a. VYa Yuriev, and 7 cultivars were of different eco-geographical origin.

Results and discussion. Over the study period, the hydrothermal regime during the pea vegetation considerably varied. Analyzing the temperature sum (Σ_t), precipitation amount (Σ_P) and hydrothermal coefficient (HTC) during the vegetation period and the yield in the study years, we found that the lowest Σ_t was recorded in 2008 (1003.2°C) with Σ_P of 119.2 mm, however, the average yield in that year was the highest throughout the study period – 4.31 t/ha. The highest Σ_t was noticed in 2013 (1349.2ºC) with Σ_Р of 97.1 mm, however, the average yield then was the lowest –1.45 t/ha. The calculated correlation coefficients showed insignificant of influence of Σ_P on the yield (r = -0.10), and the relationship between the yield and Σ_t was singnificantly inverse (r = -0.64).

Analysis of the sowing dates showed that pea was sown in April throughout the study period, and depending on the year conditions, emergence occurred 8–18 days later. In 2008–2017, the anthesis started within the first 10 days of June, except for 2014, when the anthesis started within the third 10 days of May. Pea seed formation, i.e., bean filling, starts immediately after the anthesis, therefore, the second 10 days of June were taken as the registration date for this phase.

The yield variations were insignificant in 2008–2010 and in 2017 (V = 9.08%, V = 8.60%, V = 8.96% and V = 7.74%, respectively); medium in 2011, 2012, 2015, and 2016 (V = 11.86%, V = 10.70%, V = 15.19%, and V = 14.08%, respectively); and considerable in 2013 and 2014 (V = 21.23% and V = 26.41%, respectively). Unlike the yield, the variations in the protein content in seeds in the study year were insignificant (V = 4.02–8.64%).

The yield over the study years ranged with in 0.92 t/ha - 4.80t/ha, and the protein content – within 15.59–26.01%. The average ecological yields amounted to 1.45–4.31 t / ha, the protein content of 17.90–24.04%. The variations between genotypes were within 1.85–2.42 t/ha with the variation coefficient of 31.03–47.72%. The protein content between genotypes varied from 19.45% to 23.41% with the variation coefficient of 7.24–10.34%.

Over the study years, Σ_t significantly affected the yields of nine cultivars only, and Σ_P significantly affected the protein content of eight cultivars. Kharkivskyi Etalonnyi, Oplot and Damir 2 were the only cultivars significantly influenced by the both factors. It was found that the yield was significantly influenced by Σ_t during the first 10 days of June (anthesis onset) in 11 cultivars and by Σ_P during the second 10 days of June in the majority of cultivars (20 cultivars). The protein content in seeds of all the cultivars was variously affected by Σ_P, Σ_t and HTC throughout the whole period of plant growth and development.

Conclusions. Evaluation of the effects of the abiotic factors (Σ_Р, Σ_t and HTC) on the yield and other traits on average over the study period may not be sufficiently informative. Evaluation of the effects of Σ_P and Σ_t during specific phases of vegetation on the traits may be more informative.