Harnessing perennial and indeterminant growth habits for ratoon cotton ( Gossypium spp.) cropping

Abstract

Ratoon is the stub or root of a perennial plant that is commonly retained after harvest to produce a following crop. This paper presents a review of ratoon cotton in relation to a broader framework that has been examining perennialization of agriculture for the benefit of ecology and economy. Cotton is botanically indeterminate, but has been treated as an annual after domestication, yet the habit of perenniality is retained and the plants begin to resprout after the first harvest. In some cropping systems, this tendency is exploited using the "ratooning" practice (i.e. growing one or more crops on the rootstock of the first). Ratooning has declined for various reasons such as an increase in the prevalence of pests and diseases and overwintering risk. However, ratooning has many benefits such as no annual tillage before sowing, a well-established root system, and high yield. The three methods of ratooning offer flexibility to balance the environmental and economic benefits in agriculture. The greatest environmental benefits arise from perennial ratoon cropping of semi-wild cotton, and the greatest economic benefit is obtained from biannually cropping modern annual cultivars. However, an optimum solution would be provided by perennial cropping annual cultivars. To realize both environmental and economic benefits, research is needed in the following main areas: preventing the buildup of pests and diseases, breeding the most suitable cotton cultivars for ratooning, and developing light and simplified cultivation (LSC) systems for ratoon cultivation.

Ratooning Annual Cotton (Gossypium spp.) for Perennial Utilization of Heterosis

“…The annual cotton cultivars were domesticated from perennial species in tropical and subtropical regions (Huang and Hao, 2018;Jadhav and Bhosale, 2018). However, the annual cultivated species still have perennial habits [i.e., ratooning ability (RA) which mainly refers to the ability of the ratoon crops to maintain cotton yield and fiber quality of the previous growth cycle], which can be utilized for perennial ratooning in tropical or subtropical regions, although the stalks should be pruned before the subsequent season (Zhang et al, 2020). Some studies have shown that the annual species can be ratoon cultivated for approximately 3 years while still producing high yields (Fontes et al, 2006;Zhang et al, 2015a).…”

“…However, there can be problems associated with ratooned annual cotton, such as: (1) multiple ratooning, which facilitates the accumulation of overwintering pests and diseases ( Plucknett et al, 1970 ; O’Brien, 2016 ) and leads to reductions in boll size ( Macharia, 2013 ; Zhang et al, 2015a ), and (2) susceptibility to an abnormal climate during winter, which has two different effects – stand loss during severe winters ( Sachs and Zilkah, 1985 ; Zhang et al, 2008 ) and harmful regrowth during mild winters ( Greenberg et al, 2007 ; O’Brien, 2016 ). In addition, the dramatic increase in labor costs requires implementation of a mechanized one-off cotton harvest, which is difficult to achieve in ratooned annual cotton with a long boll-opening period ( Zhang et al, 2020 ).…”

“…In terms of seed cotton yield per plant, the positive standard heterosis of intra- hirsutum hybrids was determined to reach 68.86% ( Komala et al, 2018d ). Therefore, utilizing ratoon cotton to produce inexpensive F 1 hybrid cotton seeds with high heterosis would be an effective way to improve cotton yield and quality rapidly ( Zhang et al, 2020 ).…”

“…In addition, the resistance of bollworms to pyrethroid pesticides is still high, and their resistance to Bt cotton is increasing each year. Therefore, it is difficult to control pests in ratoon cotton economically and effectively by one or two methods, and integrated pest management (IPM) must be adopted ( Zhang et al, 2020 ).…”

“…Moreover, some agronomic techniques for use in ratoon cropping of cotton have been proposed, including pruning, pest and disease control, fertilization, and hormone regulation. Notably, among these practices, pruning the stalks is the most important technique to initiate shoot growth; without this step, the ratoon cotton yield would be very low during the following season ( Zhang et al, 2020 ).…”