The characteristics of grapevine root distribution under a vertical trellis with a one side horizontal cordon trained with an inclined trunk in soilbury areas

Abstract:【Objective】In recent years, the new grape training system-“one side horizontal cordon trained with inclined trunk”under a vertical trellis system has developed quickly and shown great potential for labor-saving canopy management, integrated pest management and good fruit quality consistency in soilbury areas. However, the methods of irrigation management, fertilization and soil management didn't change in the commercial vineyards which have applied this new training system because of the lack of studies and experiments related to its root distribution. In order to provide a practical and efficient way of irrigation, fertilizing and soil management under this training system, we conducted our research to explore the characteristics of root distribution.【Methods】We used six-year old‘Ruifeng Seedless'(Vitis vinifera L.) as the plant material, whilc the growing was done in the sandy loam of the Beijing plain terrain.On October 2014, we randomly selected 4 plants whose growth vigor was similar to each other. Then we dug a ditch with a 30 cm width and 120 cm depth for a distance of 100 cm to the trunk. We then used several bamboo poles and string to fix the roots after digging and flushing the roots carefully until the whole root system was out of dirt. We performed the whole process with great patience to make sure the positions of the roots stayed the same. Then we divided the whole root system into 16 districts: horizontal 0-20 cm,20-40 cm, 40-60 and beyond 60 cm; vertical 0-20 cm, 20-40 cm, 40-60 cm and beyond 60 cm. Based on a common classification standard, the roots were classified into 5 scales in terms of diameter- scale 1,less than 2.1 mm, scale 2, 2-5 mm, scale 3, 5-10 mm, scale 4, 10-20 mm and scale 5, more than 20 mm.For each district, we first classified the roots, then we counted the root number, measured the root length and then oven dried each for 12 h to get their dry weight.【Results】For each of the four plants, similar results were obtained. For the root number: the proportion of scale 1 is 94%, and then comes scale 2, with the other scales beinge much less. Horizontally, 70%-90% of the absorbing roots were within 40 cm to the trunk; while beyond 40 cm there was another area that existed of 10%-30% absorbing roots. Vertically,the root distribution was even, 56.9%-58.5% were within 40 cm to the root collar, 41.5%-43.1% were beyond 400 cm. Unlike the absorbing root, the thick roots(scale 4 and 5), which were just three or four of each vine, and were relatively close to the trunk. Their basic function is to support the whole plant, and they intended to grow deeper instead of wider. For the root length, more than 80% were absorbing roots(scale 1), their total length were from 123 m to 208 m; and then 10% were scale 2, 3%-6% were scale 3,0.4%-1.5% were scale 4 and scale 5 was much less. There is a linear distribution between the distance from the trunk and the percentage of the main absorbing roots length in the horizontal direction: R2=0.996 7.The percentage of absorbing roots within 0-20 cm is 64.1%, 20-40 cm declined to 23.3%, 40-60 cm is8.7%, and beyond 60 cm is only 4.0%. It showed a different result in the vertical direction, R2=0.941 6.The percentage of absorbing roots within 0-20 cm is 30.4%, 20-40 cm is 27.4%, 40-60 cm is 24.7%, and beyond 60 cm is 17.6%. For the root length density(RLD), there is an exponential distribution between the distance from the trunk and the RLD of main absorbing roots in the horizontal direction, R2=0.939 9.The average RLD is above 10.5 mm·cm-3within 0-20 cm, and declined to 4.8 mm·cm-3within 20-40 cm,then 3.5 mm·cm-3within 40-60 while it is 1 mm·cm-3beyond 60 cm. In the vertical direction, RLD is 7.7mm·cm-3within 40-60 cm, 5.8 mm·cm-3within 0-20 cm, 4.3 mm·cm-3within 20-40 cm, and 2.2 mm·cm-3beyond 60 cm.【Conclusion】For this study, we explored and understood the basic characteristics of root distribution under a vertical trellis with a“one side horizontal cordon trained with inclined trunk”in Beijing terrain with sandy loam soils. The results showed that the current way of fertilizing is suitable for this training system. The fertilizing strip is about 40 cm from the trunk where the most absorbing roots are concentrated. In addition, this study provided information on how to make a drip irrigation system. Since most absorbing roots are close to the trunk, a 40 cm spaced dripper can satisfy 80% of the absorbing roots so that one drip line for each row is enough, and an extra dripper or design is unnecessary. For vineyards that intend to apply this training system, we have the following suggestions: 1, Trench deeply when planting the vines, apply adequate amounts of organic matter to improve the soil condition and make the vine developing both vertical and deep. 2, Fertilize on the top of the soil instead of trenching, also, drip irrigation could bring the fertilizer down to about a 40 cm depth. 3, Within the row, use soil mulching to reduce evaporation; between the rows, use soil mulching or grass to make the whole vineyard labor-saving and environmentally friendly.