| In arid and semi-arid areas of northern China,‘White pollution’ has also increased withpopularization and application of plastic film, in consideration of used film pollution under‘full plastic-film mulching on double ridges and planting in catchment furrows’ maize andlow and unstable oil flax actual production, it is important that studying sustainbale use forused film, which was helpful to ensure current ecological security and circular agriculturedevelopment. Field experiments were conducted to investigate oil flax growth and developingconditions, filling traits, physioecological characteristics, variety in soil water andtemperature, yield and water use efficiency(WUE), et al, under different reuse pattern anddifferent planting density in Dingxi city in Gansu province from2011to2012. This researchwill be a general reference and instruction for diversity of used film utilization and high-yieldculture technique in oil flax. The main results obtained are as follows:1. The main topsoil effected water retaining is in0-60cm soil layer under different reusepattern before budding stage, among the six treatments, the water retaining effects showedthat used plastic film> new plastic film> open culture treatment in oil flax early stage(sowing stage-seedling stage); new plastic film> used plastic film> open culture in middlestage (momi fir pattern stage-flower stage); there are no significant difference for soil waterstorage in maturation stage. So, the treatment of field-kept film with replacement by newplastic film and no-tillage sowing the next year(T4) has a obvious function for storagingmoisture, it was embodied in pre sowing stage, seedling stage and momi fir pattern stage, butdecreased after budding stage. As no significant difference of soil moisture content amongfield-kept film with straw mulching the current year and no-tillage sowing after straw clearingthe next year (T3), field-kept film with earth mulching and no-tillage sowing the next year(T2) and field-kept film and no-tillage sowing the next year (T1), the higher water maintaining effect has not appeared under the straw mulching and thin soil mulching. Withthe increased soil thickness and the oil flax development process, soil accumulatedtemperature difference appeared in15cm soil layer in sowing and seedling stage, then, theeffects updrifted in10cm soil layer in momi fir pattern stage. The soil temperature retainingeffects under different reused patterns showed that new plastic film> used plastic film> openculture treatment (T6, CK), soil accumulated temperature of film collection with landpreparation and new plastic film mulching just after harvest and sowing the next year (T5),field-kept film with replacement by new plastic film and no-tillage sowing the next year(T4),field-kept film and no-tillage sowing the next year (T1), field-kept film with earth mulchingand no-tillage sowing the next year (T2) and field-kept film with straw mulching the currentyear and no-tillage sowing after straw clearing the next year (T3) increased by216.53℃,172.21℃,110.06℃,112.98℃and94.66℃, whole growth period less than15.6d,17.4d,10.9d,5.8d and10.1d, respectively, over the control(T6).2. Relative growth rate (RGR) and net assimilation rate(NAR) in oil flax plant ascended byused film utilization, the same trend also appeared in dry matter accumulation. But, influencewas replaced by new film (T5) after flowering. Contribution of dry matter assimilationamount after anthesis to grain (CDMAAAATG) showed that T4>T5>T1>T2>T3>T6(CK),amount to71.93%,68.10%,65.16%,64.23%,61.01%and57.11%, respectively, over thecontrol. T4treatment has a significant positive effect on increasing leaves’ SOD activity andretaining soluble protein content, and the effect of new film mulched in current year wassuperior to new film mulched in previous year. It was also appeared that leave SOD activitydifference becomes smaller among the6treatments and T5leave MDA content becomeslarger than others5treatments in late maturation period. SOD activity and soluble proteincontent under T2has declined in early growth stage. The proline content appeared tounanimity among different treatments and growth stages, only in momi fir pattern stage,higher proline content be founded in T4, T5and T3. As a result, used film reusing show thatdelaying senescence, promoting osmotic regulation and enhancing oxidation resistance, andso on, and the functions also be effected by using time length, interactction between used filmand straw, thin soil layer, growth stage.3. The study concluded that sparse seeding is favored to accumulating dry matter, increasing grain dry weight and obtaining high yield in conditions of300～1200ten thousand grain.hm-2,plants number150～415ten thousand plant.hm-2under one film used for two years. Theresearch showed that total dry matter accumulation content per plant and dry weight of grain,leaves, Stem+spike axis+kernel husk decreased with sowing density increases. Contributionof dry matter assimilation amount before anthesis to grain(CDMAABATG) also decreasedwith sowing density increases, difference amplitude amount to79.09kg·hm2～508.69kg·hm2, and the contribution after anthesis to grain has a opposite trend, difference amplitudeis in55.58kg·hm2～272.99kg·hm2, the optimal response on low-density for yield formationwas embodied in accumulating content before flowering, the same trend as the NAR variation.RGR decreased with sowing density increases after budding stage. Oil flax grain fillingcourse was divided three phases as gradual growth period(3～6d), rapid growth period(6～31d) and slow growth period(28～38d) after well fitted by Logistic equation(r>0.99), graindry weight accumulation in the three periods was up to7.89%～15.79%,57.89%～65.79%,18.42%～26.32%, respectively. The second phase(6～31d) provided a highest contribution tograin weight rising. Time to the maximum of filling rate under different density treatmentswere divided by750ten thousand grain.hm-2(T4), reduced in low density but increased inhigh density. There was negative correlation between planting density and yield componentfactors, such as stem number, branch number and capsule number, but no obvious correlationwith plant height.4. Both increasing oil flax yield production and reducing water consumption were suggestedin the study after used film utiliazation. Yields of T4, T5, T1, T2and T3increased by143.26%,120.91%,88.84%,86.69%and62.98%, respectively, over the control. The sametrend appeared in water use efficiency among the five reused pattern, which is2.53,2.29,1.97,1.85and1.64times over the control.5. In conditions of300～1200ten thousand grain.hm-2, plants number150～415ten thousandplant.hm-2under one film used for two years, effects of different soil layer moisture contentand0-100cm soil water storage focused on the period that between vegetative growth andreproductive growth, while the soil moisture content in low-density treatments were prior tohigh-density, and the status was mainly embodied in budding stage. There was negative effectbetween planting density and grain yield, the same effect between sowing density and water use efficiency, the highest yield and WUE in300ten thousand grain.hm-2(D1) were up to1837.95kg.hm-2and11.71kg.hm-2.mm-1, increased by27.47%and30.69%, respectively, over1200ten thousand grain.hm-2(D7). In conclusion, according to rainfall conditions in centraland eastern area of Gansu province and oil flax filling characteristics in our field experiments,density of300～450ten thousand grain.hm-2were suggested as optimal planting measure foroil flax production under one film used for two years. |
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