Field Crops Research 207 (2017) 62–70 Contents lists available at ScienceDirect Field Crops Research journal homepage: www.elsevier.com/locate/fcr Genotype by environment interactions for grain yield of perennial rice derivatives (Oryza sativa L./Oryza longistaminata) in southern China and Laos a b b c c d Shilai Zhang , Jian Hu , Chundao Yang , Haitao Liu , Feng Yang , Jihua Zhou , e f a a Ben K. Samson , Chanthakhone Boualaphanh , Liyu Huang , Guangfu Huang , a g g h i,∗ Jing Zhang , Wanqi Huang , Dayun Tao , Dome Harnpichitvitaya , Len J. Wade , a,∗∗ Fengyi Hu a Yunnan University, School of Agriculture, Chenggong District, Kunming, China b Centre of Agricultural Technology Extension of Jinghong County, Jing Hong, China c Puer Agricultural Science Research Institute, Puer, China d Centre of Agricultural Technology Extension of Menglian County, Menglian, China e IRRI-Laos, c/- National Agricultural and Forestry Research Institute, Vientiane, Laos f National Agricultural and Forestry Research Institute, Vientiane, Laos g Yunnan Academy of Agricultural Sciences, Kunming, China h Ubon Ratchathani Rajabhat University, Ubon Ratchathani, Thailand i Charles Sturt University, Graham Centre, Wagga, NSW 2678, Australia a r t i c l e i n f o a b s t r a c t Article history: Perennial grains have been proposed to stabilise fragile lands while contributing grain and grazing in Received 17 October 2016 mixed farming systems. Genotype by environment (GxE) interactions for grain yield were investigated in Received in revised form 8 March 2017 22 perennial rice (Oryza sativa L./Oryza longistaminata) derivatives over four successive growing seasons Accepted 8 March 2017 at three sites in Yunnan in southern China and one site in Lao PDR. The GxE interaction accounted for 25.7% of the total sum of squares, with environment and genotype responsible for 57.4% and 16.9%, Keywords: respectively. Cluster analysis identified seven environment and six genotype groups, which accounted Adaptation for 55.6% of the GxE sum of squares. Principal component axes 1, 2 and 3 accounted for 42.3%, 19.1% and Land stability 16.5% of the GxE-SS, respectively, with PCA1 indicating yield potential, PCA2 delay in phenology under Minimum temperature environmental stress, and PCA3 ratoon percentage. Environment groups differed in mean temperature, Rainfall deficit Perennial crops whether dry season or wet season, and occurrence of environmental stresses, such as periods of low minimum temperature or periods of rainfall deficit. Genotype groups differed in adaptation to these diverse environments. For genotype groups, G5 (PR23) was highest-yielding and broadly adapted across environments, while G1 (line 188, both 137s, both 139s, both 147s) was low-yielding and poorly adapted. Other genotype groups showed preferential adaptation: G3 (lines 60, 251, 264, Bt69, Bt71) to Simao/Dry Season (E3 and E4), G4 (lines 75, 243, 246, 249, 255) to Menglian/Wet Season (E1 and E2), G2 (line TZ) to Jing Hong 2013 (E7), and G6 (lines 56, 59, 214) to Jing Hong 2102 and Na Pok (E6 and E5). The results imply that regrowth success and maintenance of spikelet fertility over regrowth cycles are important for adaptation of perennial rice, especially to low minimum temperature at higher altitude and rainfall deficit at lower altitude, and future breeding programmes in perennial rice should address these environmental stresses. The high yield and broad adaptation of PR23 (G5) over environments makes it a prime candidate for release to stabilise fragile lands in the humid and subhumid tropics, while contributing grain and forage in mixed-farming systems. © 2017 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Abbreviations: GxE, genotype by environment interaction. ∗ Corresponding author. Present address: The University of Queensland, School of Agriculture and Food Sciences, Brisbane QLD 4072, Australia. ∗ ∗ Corresponding author. E-mail addresses: [email protected] (L.J. Wade), [email protected] (F. Hu). http://dx.doi.org/10.1016/j.fcr.2017.03.007 0378-4290/© 2017 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). S. Zhang et al. / Field Crops Research 207 (2017) 62–70 63 Table 1 1. Introduction The 12 environments used to discriminate perennial rice genotypes (l.s.d. = 0.34; P = 0.05). Global food security is under threat, due to rising global popu- −1 Number Site Year Season Code Yield (t ha ) lation, pressure on the resource base, and climate change. While 2 the best lands (16.5 million km ) have soils of low to moderate 1 Jing Hong 2012 Dry J2D 6.04 risk of degradation and capable of sustaining high-yielding annual 2 Jing Hong 2012 Wet J2W 2.05 3 Menglian 2012 Dry M2D 3.07 crops, more than 50% of world population relies on marginal lands 2 4 Menglian 2012 Wet M2W 4.06 (43.7 million km ), which are at high risk of degradation under 5 Simao 2012 Dry S2D 2.63 annual cropping (Eswanan et al., 1999). For sustainable production, 6 Na Pok 2012 Wet N2W 0.94 marginal lands in particular require agroecosystem consideration, 7 Jing Hong 2013 Dry J3D 2.23 8 Jing Hong 2013 Wet J3W 1.17 to ensure their health and viability in the long term. Most likely, 9 Menglian 2013 Dry M3D 3.15 this requires maintenance of ground cover and biodiversity, so soil 10 Menglian 2013 Wet M3W 1.79 resources are retained in situ (Tilman et al., 2011). Perennial grains 11 Simao 2013 Dry S3D 1.42 have been proposed to have an important role there (Glover et al., 12 Na Pok 2013 Wet N3W 1.93 2010), by stabilising land and soil resources, while contributing Mean 2.54 grain, grazing and forage in a mixed farming system, in conjunc- tion with associated rangeland, pasture, forage, annual crops and vegetables. Livestock usually form part of the farming system on derivatives in up to four growing seasons in each of four locations, marginal lands, so integration of livestock with crop, pasture and (2) to consider traits needed for successful adaptation to this tar- forage should enhance farmer livelihood and system sustainabil- get population of environments, and (3) to identify implications for ity, and perennial crops can serve as both grain and forage (Bell selection, release and farmer livelihood. et al., 2008; Pimentel et al., 2012). While the pressure is on the best lands to sustain the grain pool for food security under high- yielding irrigated crops, marginal lands can assist food security via 2. Materials and methods system flexibility and diversity, with integrated crop-livestock sys- tems. The intent is not to displace high-yielding annual grain crops 2.1. Planting location, experimental design and plot management from the best land, as that would require extra land be brought into cropping to compensate. Rather the intent is more efficient The experiments were conducted in 12 site-season-year (Envi- ◦ ◦ integrated systems for marginal lands, with dual-purpose perennial ronment E) combinations, at Jing Hong (21 59 N, 100 44 E, ◦ ◦ ◦ grains (Wade, 2014). 611 m), Menglian (22 33 N, 99 59 E, 955 m) and Simao (22 79 N, ◦ Research is underway to develop perennial versions of a num- 100 96 E, 1340 m) in Yunnan Province of southern China, and at ◦ ◦ ber of annual grain crops (Batello et al., 2014), in order to facilitate Na Pok (17 57 N, 102 34 E, 171 m) in Vientiane Province of Lao the expected systems benefits. Two approaches are possible; either PDR. Each of the four sites was continued for two years, 2012 and domestication of a perennial species, or wide hybridisation of 2013, with the potential for up to two crops to be harvested each the annual crop with a perennial relative. Domestication requires year, from the dry and wet seasons, respectively. While rice may selection for agronomic type including non-shattering and larger ratoon or reshoot from basal nodes after harvest in suitable condi- grain size (Dehaan et al., 2014). Wide hybridisation, which requires tions (Douthwaite et al., 1995), ratoon potential is expected to be embryo rescue in some instances, can be used to introgress desired stronger in perennial rice derivatives being evaluated here. At each characteristics such as perenniality into the annual crop germplasm site, a randomised complete blocks design was used, comprising pool, via selection for ratooning ability and sustained floret fertility 22 genotypes with 2–3 replicates. Long-term weather data showed (Cox et al., 2002). The development of perennial rice was proposed minimum temperatures were lower at the higher altitude sites in in order to stabilise fragile upland farming systems (Schmit, 1996). the north (Supplementary Table 1), especially at Simao, so only one A successful wide hybrid between the annual rice Oryza sativa and dry season crop per year could be harvested there. Likewise, rainfall the wild perennial rice Oryza longistaminata was reported (Tao and declined from Na Pok to Simao and Menglian to Jing Hong (Supple- Sripichitt, 2000). Viable progeny from the wide-hybrid segregat- mentary Table 2), but with a more pronounced difference between ing for perennality were created (Sacks et al., 2003, 2006), which wet and dry seasons at Na Pok, which allowed only one wet sea- allowed for greater understanding of the genetic architecture of son crop per year to be harvested there. Consequently, data were perenniality (Hu et al., 2003, 2011), and proposals for additional available for GxE analysis from a total of 12 Environments (Table 1), traits that could be introgressed from the wild perennial species which for simplicity, are referred to by their environment code, e.g., into the annual cultivated rice germplasm.