Variation in the Meteorological Conditions on the Date of Sowing in Spring and its Effects on the Sowing of Maize in Liaoning Province During 1981�2014

Research Article

Austin Food Sci. 2016; 1(4): 1020.

Variation in the Meteorological Conditions on the Date of Sowing in Spring and its Effects on the Sowing of Maize in Liaoning Province During 1981–2014

Li J, Li RP*, Huang Y, Wang WZ, Liu DM and Zhou B

Liaoning Institute of Meteorological Science, China

*Corresponding author: Li RP, Liaoning Institute of Meteorological Science, Shenyang, China

Received: June 09, 2016; Accepted: September 06, 2016; Published: September 14, 2016

Abstract

Exploring the effects of meteorological conditions on sowing of corn in spring is helpful to fully understand the changes of the maize planting system, cultivar used, and provide a strong basis to facilitate decision-making for the national food security. Based on climatic data and corn sowing data over 35 years in Liaoning Province, the temporal and spatial variations of climate conditions were analyzed, and their effects on maize spring sowing date were explored. The results showed that, over this period, the rainfall, amount of Available Soil Water at Planting (ASWp) and spring sowing rain tended to increase in most parts of Liaoning Province. The first date when more than 10mm of precipitation was received for three consecutive days seemed to have advanced, indicating that the appropriate water conditions for sowing started much earlier. The average air temperature on the date of sowing in spring increased slightly, and the date when the daily average temperature was equal or more than 8°C advanced, which indicated that the suitable heat conditions for maize sowing came much earlier. All of these showed that climate change contributed to the bringing forward of maize sowing. However, the actual sowing date tended to be postponed because the appropriate growth period was extended as a result of climate warming, owing to high planting density, and because varieties that were adapted for higher base temperature were selected. In addition, sowing date was delayed because of the increased number of frost days and wet soil in spring.

Keywords: Maize; Spring sowing date; Climate change; Soil water content

Introduction

The ratio of area under maize cultivation in Northeast China compared to that of the entire nation was 30.9%. This included an area of 2.33×106 hm2 in Liaoning Province, which accounted for 72.0% of all food crops in 2014. Crop growth is mainly driven by rainfall and temperature [1], as a result, the climate change, resulting in changes in these factors, is a great challenge on food security [2]. Maize production security is an important part of national grain security. Liaoning Province is ideal for maize cultivation in spring. Consequently, exploring the responses of maize production to climate change has important significance to fully understanding the adaptive mechanisms of spring maize to climate change.

Under the background of climate change, rain-fed agriculture has become the most vulnerable agricultural ecosystem [2-4]. The maize production in Northeast China is mainly dependent on the rainfall. The distribution of precipitation in the Liaoning Province is uneven, and especially in the western region, drought occurs frequently, which seriously hampers the stability and increase local maize yield. In the past 50 years, climate change has led to the decrease of potential yield by 2.1% in Northeast China [5]. However, an increase in production can be achieved by adopting appropriate agricultural practices and selecting suitable varieties. Selecting the date for sowing is one such important management measure to improve food production. Many studies [6,7] have reported that early sowing can increase yield and vice versa.

For maize, the choice of sowing date is mainly dependent on soil moisture and air temperature conditions [8]. Maize is a suitable crop when the daily average temperature is stable at a minimum temperature of 8°C and the soil relative humidity range is between 60% and 70%. The most suitable condition for germination is when the daily average temperature is between 18°C and 20°C. When the soil temperature at 10 cm depth is lower than 5°C, the seedlings do not easily emerge. The seed cannot be germinated when the soil relative humidity is lower than 40%. In terms of water condition, when the amount of rainfall is high and the Available Soil Water at Planting (ASWp) is enough, farmland soil can keep more water after freezing, and mudding phenomenon appears in the following year due to thawing of the soil, which is helpful to maize sowing in spring. Furthermore, the date of the first ‘soaker’ rain, i.e., rainfall that was heavy enough to soak the soil completely, is one of the key water indicators to determine the sowing date for maize crop [9,10]. Pertaining to heat condition, the number of frost days after April and temperature stability pass 8°C are important indexes that indicate the appropriate time to sow maize.

Studies on changes in the hydrothermal conditions have been reported earlier. However, the effect of changing meteorological condition on maize sowing has been unclear. Thus, the objectives of this study were (1) to analyze quantitatively the varying characteristics of meteorological conditions in spring maize sowing in Liaoning Province, and (2) discuss the effects of changing hydrothermal condition caused by climate change on the spring sowing of maize. This study will provide the scientific basis for developing an adaptive strategy to overcome the effects of climate change, making full use of agricultural climate conditions, and reasonably altering the spring farming activities to ensure a steady, and possibly an increased agricultural production.

Materials and Methods

The study area

Liaoning Province is located in the southern part of the Northeast China (118°53’-125° 40’ E, 38°43’-43° 26’ N). The terrain is mountainous on both the eastern and western sides and there are rectangular plains from northeast to southwest (Figure 1). The region belongs to the temperate continental climate zone. The temperature in this region is warm enough for maize cultivation. There is a vast difference in rainfall among the various regions in Liaoning Province. It is humid in the eastern region, while the rainfall in the hills of the western region is only 400mm, representing the semi-arid climate type. Annual precipitation is mainly concentrated in summer (June– September). Rainfall is relatively stable and consistent with the peak period of the crop’s water requirement. Grain cropping system is typically one crop annually, and the main crops include rice, maize, soybean, sorghum, etc. The normal date for spring sowing is from early April to mid-May (Figure 1).