农艺与气候因素对青藏高原栽培大麦淀粉含量空间分布的影响

Effects of agronomic and climatic factors on the spatial distribution of starch concentration in barley cultivated on the Qinghai-Tibet Plateau

为了揭示不同环境因子对青藏高原栽培大麦籽粒淀粉含量(GSC)积累的影响程度,完善大麦GSC空间分异与环境因子的关系,明确青藏高原不同地区大麦品种GSC的环境效应,利用83个样点的地理、气候、土壤、农艺因子数据,研究了青藏高原栽培大麦GSC的分布特征,结果表明:(1)在地理水平方向上,青藏高原栽培大麦GSC的水平分布总体呈现出斑块状交错分布和南高北低的格局,并形成了以西藏拉孜、隆子、堆龙德庆、曲水、尼木、定日、萨迦、达孜、扎囊、日喀则、墨竹工卡、贡嘎、琼杰为中心的青藏高原中南部和以青海共和、贵德、海晏、同德为中心的青藏高原东北部等2个栽培大麦GSC高值区;(2)在地理垂直方向上,栽培大麦GSC的变化呈现出"S"型分布格局,即在海拔3300.0—3600.0 m以上,随着海拔的升高,栽培大麦GSC逐渐增加,在海拔4200.0 m与4500.0 m之间达到最高值,此后随着海拔的升高略有下降;(3)影响栽培大麦GSC的因子从大到小的顺序是穗密度﹥6月平均气温日较差>芒长﹥9月平均气温>1月平均气温>年日照时数﹥≥0℃积温>5月平均气温﹥8月平均气温日较差>8月平均气温>6月平均气温>≥10℃积温>6月平均月降水量>5月平均月降水量>7月平均相对湿度>8月平均相对湿度>7月平均气温。这一研究结果显示,对栽培大麦GSC影响最大的是基因型,其次是气候因素,土壤因素对GSC的影响不明显。影响栽培大麦GSC的农艺因子主要是穗密度和芒长,气候因子主要是拔节抽穗期的气温日较差和籽粒灌浆成熟期的平均气温,日照和降水的影响相对较小。

Starch concentration is an important quality character of barley grain. In recent years, some researchers have realized that barley grain starch concentration （GSC） is affected by genetic factors, as well as by its cultivation and environmental conditions. However, the effect of different environmental factors on barley GSC remains unclear. In addition, previous studies have mostly been conducted at several sites, and large-scale studies have not addressed the relationship between cultivated barley GSC and environment factors. The Qinghai-Tibet Plateau is an important region for growing hull-less barley in China, and the relationship between barley GSC and environment factors on the Qinghai-Tibet Plateau have not been reported. Therefore, the present study investigated the distribution of barley GSC on the Qinghai-Tibet Plateau using geography, climate, soil, and agronomy data from 83 sampling sites, the cultivated barley GSC distribution characteristics in Qinghai-Tibet Plateau was studied in this research work. The aim of the study was to identify the relative effects of different environmental factors on GSC, to clarify the relationship between the distribution of barley GSC and environmental factors, and to get explicit GSC acclimation of barley varieties planted in different areas to environment. The results showed that （1） GSC exhibited a macrocosm pattern of spatial distribution along the horizontal direction on the Qinghai-Tibet Plateau, with staggered patches of different value and a tendency of ＂high in the south and low in the north＂. In addition, two regions of higher GSC （south-central and north-eastern） included the Lazi, Longzi, Duilongdeiqin, Qushui, Nimu, Dingri, Sajia, Dazi, Zhanang, Shigatse, Mozhugongka, Gongga, and Qiongjie Counties in Tibet and the Gonghe, Guide, Haiyan, and Tongde Counties in the Qinghai Province. （2） Along the vertical direction, GSC exhibited an S-shaped distribution pattern. Indeed, GSC increased gradually with increasing altitude from 3300.0-3600.0 m, reached its maximum between 4200.0 m and 4500.0 m, and thereafter slightly decreased with increasing altitude. （3） The relative effects of the environmental factors on barley GSC were as follows： spike density 〉 average diurnal temperature range in June 〉 length of the awn 〉 average temperature in September 〉 average temperature in January 〉 annual sunshine hours 〉 accumulated temperature （≥0 ℃） 〉 average temperature in May 〉 average diurnal temperature range in August 〉 average temperature in August 〉 average temperature in June 〉 accumulated temperature （≥10 ℃） 〉 average precipitation in June 〉 average precipitation in May 〉 average relative humidity in July 〉 average relative humidity in August 〉 average temperature in July. Therefore, genotype had the greatest impact on the GSC of cultivated barley, followed by climatic factors, and the effects of soil factors effect were not apparent. Spike density and length of the awn were the most important agronomic factors, and diurnal temperature range during the period of elongating and heading and average temperature during the period of filling and maturation were the main climatic factors, whereas the effects of sunshine hours and precipitation were relatively small. These findings support previous reports that barley GSC is mainly controlled by the characteristics （i.e., genetic factors） of individual barley varieties, although the effects of environmental factors were also apparent.