Citation: S , imon, A.; Moraru, P.I.; Ceclan, A.; Russu, F.; Chet , an, F.; B˘ ardas , , M.; Popa, A.; Rusu, T.; Pop, A.I.; Bogdan, I. The Impact of Climatic Factors on the Development Stages of Maize Crop in the Transylvanian Plain. Agronomy 2023, 13, 1612. https://doi.org/10.3390/ agronomy13061612 Academic Editors: Konstantina Kocheva and Tania Kartseva Received: 27 May 2023 Revised: 10 June 2023 Accepted: 13 June 2023 Published: 15 June 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). agronomy Article The Impact of Climatic Factors on the Development Stages of Maize Crop in the Transylvanian Plain Alina S , imon 1 , Paula Ioana Moraru 2, * , Adrian Ceclan 1 , Florin Russu 1 , Felicia Chet , an 1, *, Marius Bărdas , 1 , Alin Popa 1 , Teodor Rusu 2 , Adrian Ioan Pop 2 and Ileana Bogdan 2 1 Agricultural Research and Development Station Turda, Agriculturii Street 27, 401100 Turda, Romania; alina.simon@scdaturda.ro (A.¸ S.); adrian.ceclan@scdaturda.ro (A.C.); florin.russu@scdaturda.ro (F.R.); marius.bardas@scdaturda.ro (M.B.); alin.popa@scdaturda.ro (A.P.) 2 Department of Technical and Soil Sciences, Faculty of Agriculture, University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca, Mănăstur Street 3–5, 400372 Cluj-Napoca, Romania; trusu@usamvcluj.ro (T.R.); adrian.pop@usamvcluj.ro (A.I.P.); ileana.bogdan@usamvcluj.ro (I.B.) * Correspondence: paulaioana.moraru@usamvcluj.ro (P.I.M.); felicia.chetan@scdaturda.ro (F.C.) Abstract: Climate change has become the biggest global challenge, being a real danger especially for crops and an inevitable threat to food security. This paper presents the results of a study conducted in the Transylvanian Plain during 2012–2021, regarding the influence of climatic factors, such as temperature, rainfall, water reserve in the soil and hours of sunshine, on the development stages and yield of maize. During 2012–2021, the soil water reserve determined for maize cultivation was above the minimum requirements (1734.8 m 3 ha −1 ) in the spring months, but fell below this limit in the months when the water consumption for maize was the highest, but without reaching the withering index (1202.8 m 3 ha −1 ). The hours of sunshine in the maize vegetation period have been significantly reduced from 1655.5 h (2012) to values between 1174.6 and 1296.7 h, with a significant decrease in this parameter being observed. The coefficient of determination (R 2 = 0.51) shows the importance of rainfall during the period of emergence of reproductive organs in maize production. During 2019–2021, there was a decreasing trend of temperatures in May compared to the multiannual average of this month, and therefore the processes of emergence and growth of plants in the early stages were affected. During the period of the study, all parameters analyzed (temperature, rainfall, water reserve in the soil, hours of sunshine) deviated from the multiannual average, with negative variations compared to the requirements of maize. Climatic conditions, especially during the growing season, have a significant influence on the yield of a crop, especially when the interaction between several parameters is manifested. Keywords: climatic conditions; water reserve in the soil; maize; crop development 1. Introduction It is unanimously accepted that current climate change is the result of direct or indirect human intervention in the composition of the global atmosphere [1]. Climate change has become the biggest global challenge, raising issues in terms of crop development and yield [2,3], through rising temperatures and uneven rainfall, leading to threats regarding food security for the growing population [4,5]. The problem of fluctuating climate has become more certain in the last two decades, when yield variability has become greater [6]. Maize (Zea mays L.) is a cereal with a large yield capacity [7] and with a widespread area being influenced by climate change [8]. Medium early maize genotypes are characterized by a lower sensitivity to higher temperatures and drought during the grain-filling period and could contribute to the ability of new hybrids to counteract the effects of climate change, having a high resistance to diseases and pests, and thus agricultural and harvesting works can be fully mechanized. Currently, maize is one of the most important crops due to Agronomy 2023, 13, 1612. https://doi.org/10.3390/agronomy13061612 https://www.mdpi.com/journal/agronomy