Soil moisture management of selected maize (Zea mays L.) cultivars in northeast Thailand | |
| Author | Satiraporn Sirisampan |
| Call Number | AIT Diss. no.AS-04-09 |
| Subject(s) | Soil moisture--Thailand, Northeastern Corn--Soils--Thailand, Northeastern |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctoral Technical Science, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. AS-04-09 |
| Abstract | In northeast Thailand, maize (Zea mays L.) is mainly grown under rainfed conditions. In this region, frequent dry spells are often the cause of periodic drought stress that leads to decreased yields, especially when drought occurred during the critical growth stages. The objective of the study was to identify and assess variety and soil moisture conservation (SMC) practice effects on the growth and yield of maize under temporary drought stress. The study was carried out at two scales, with on-station experiments and on-fann field trials. The on-station experiments were process-oriented. They had two main objectives; (1) to obtain basic phenological information on drought tolerance at different growth stages for the selected varieties (preliminary experiment); and (ii) to characterize and quantify the soil processes and plant responses under different SMC practices. The on- farm field trials aimed to quantify the effects of different SMC practices compared to the practices used by the local farmers. The on-station experiments were carried out at the Agricultural Systems Experimental Farm of the Asian Institute of Technology, about 30 km north of Bangkok. The on-farm field trials were located in Pak Chong District, northeastern Thailand, about 170 km east of Bangkok. To eliminate the effects of nutrient deficiency, fertilizer was applied at super-optimum rate. The preliminary on-station experiment tested three maize varieties, i.e. Suwan5 (an Open-pollinating variety), Big717 and Big949 (single hybrids) and the five different water regimes, i.e. adequate water supply throughout (AW), water deficit at 1 week before tasseling vegetative stage (l-Ts), water deficit at tasseling (Ts), water deficit at silking (Slk), and water deficit throughout the experiment (DW). In the other on-station experiment, the same maize varieties were tested in combination with five SMC practices, i.e. conventional farmer practice no residues incorporated (CT), mungbean (Vigna radiator (L.) Wilzek) residue incorporated as practiced in a mungbean maize rotation (Mn), spineless mimosa (Mimosa invisa) live mulch intercropped and incorporated (Mi), cattle manure incorporated (Ma), and mulching with commercial plastic sheeting as a control treatment for the best soil moisture conservation (P1). The temporary water deficit was induced at the respective stages (in the preliminary experiment) and at the flowering stage (in the experiment on SMC practices) until the plants showed wilting signs, such as folded leaves throughout the day. The wilting condition was maintained for three days; then, the plants were re-watered as usual. The soil used in the experiments was a clay loam. For the on-farm trials, one variety (Big717, popular with farmers in the study location), was tested under natural conditions with five SMC practices, i.e. maize-maize system naize is cultivated twice a year with maize residue incorporated (Mz), mungbean-maize system mungbean (Vigna radiara (L) Wilzek) residue incorporated for the following maize crop (Mn), maize intercropped with spineless mimosa (Mimosa invisa) as live mulch (Mi), maize-maize system with cattle manure application (Ma), and maize-maize system with residues burnt in the field conventional fanner practice in the area used as c0ntrol (benchmark) for the other treatments (CT). The soil on the experimental site was a sandy clay loam. The general outcome of the study was that the variety effects were more prominent than any of the SMC practices. The open-pollinating variety Suwan5 in particular gave significantly lower yields (both grain and total aboveground biomass) than the two hybrids. iiiUnder drought stress near wilting point at flowering stage, Big717 was least sensitive to the SMC practices and gave the highest yields in the on-station experiment. Among the three selected varieties, Big?! 7 showed the best drought tolerance. It was also found that water deficit at any stage reduced grain yield and total aboveground biomass. The most critical stage for yield losses was at flowering, in which silking (Slk) was the most critical followed by tasseling (Ts). Drought stress at the vegetative stage (l-Ts) was least critical. When water deficit was high (near wilting point) and at the critical growth stage (at flowering), manure application (Ma), live mulch of spineless mimosa (Mi) and mungbean residue incorporated (Mn) tended to give essentially low yields. Generally, Ma gave the lowest yields. This was probably because the Ma- treatment plants generally grew more vigorously than the others at the vegetative stage when water was not limited. Later on during the drought-stress period, these more sturdy plants consumed more water (evidenced by lower soil moisture with the Ma treatment during water suspension in the on station experiment) than the smaller plants in the other treatments. This may have led to the Ma plants being subjected to more severe water shortage (i.e., drought tress) than the plants in the other treatments, and hence producing considerably lower yield. It can be concluded here that well-grown plants that require larger quantities of water to keep the biomass alive will react more sensitively to drought stress during the flowering stage than plants with smaller biomass at that stage, leading to reduced grain yields. Under uncontrolled conditions (on-farm trials), with fairly evenly distributed rainfall (1St crop) both grain and biomass yield under the manure application practice (Ma) were generally higher than in the other treatments. In the crops with water stress at grain- filling (2nd crop) and at flowering (3rd crop), grain and biomass yields of Ma were not much higher than that of the other residue-adding treatments, i.e. maize-maize cropping (M2), mungbean-maize cropping (Mn), and live mulch of spineless mimosa (Mi). It may be concluded that with slighter drought stress, Ma is probably more effective for grain- yield improvement. With intensified drought stress near wilting point at the flowering stage the yield will be adversely affected by Ma-treatrnent. Per-area yield of Mn was higher than that of the other treatments, because of the high plant population. This was because of the smaller amounts of residues from Mungbam than from maize in the other treatments which obstructed the seeding Operations and led to lower plant populations in the other treatments. Mi gave yields as high as with Ma and Mn, except during the first crop. Spineless mimosa might require time to accumulate organic matter in the soil and could not have an effect on the crop yield during the first crop. It also competed with the cr0p for both water and nutrients. Overall, CT with residues burnt resulted in the lowest yields. Plants with water deficit during tasseling (Ts) delayed silking and prolonged tasseling-silking interval (TSI). Drought stress at silking (Slk) led to poor pollination and seed setting because of drying silks, resulting in lower final grain yield. With near wilting point at flowering, the plants with the largest girth and tallest height in the on station experiment were with the Ma treatment. These well-grown plants displayed a significant delay in sulking (particularly for vaan5 and Big949) thus increasing the T81. These plants therefore had a higher incidence of abortion during the reproductive stage, and hence produced lower grain yields. Between the varieties, Big717 was the least affected by the treatments in term of TSI. Under field conditions, with slighter drought stress than in the iron-station experiment, the T31 was not affected by SMC practices. SMC treatments probably need more severe drought to show effects. An important assumption of the study was that the experimental treatments (i.e., the SMC practices) would condition the soil by modifying its moisture-retention properties. But with the high levels of drought stress occurring during the period of water suSpension in the on station experiment, the water-depletion effects probably overshadowed the SMC- practice effects. Water holding capacity (WHC) was only improved slightly (non- significant) with the Ma, Mi and Mn treatments. Therefore, the differences in yield between the treatments were not due to changes in the WHC of the soil, but rather due to the effects of the treatments on plant growth. It is recommended that variety selection is still's potential management tool to reduce or avoid drought stress on plants. Between the three selected varieties, Big717 was the best variety in conjunction with any SMC practices (non-significant differences between SMC treatments) in terms of drought tolerance. Carefully adjusting planting dates to avoid drought periods at flowering, particularly at the silking stage, will help minimizing drought stress. Overall, removing or burning residues (CT) from the field should be avoided. Live mulch of spineless mimosa (Mi) appears to be an alternative for the farmers who can make long-term investments in soil improvement. For locations with recurrent periods of drought stress, such as the on-farm field-trial site, the M2 practice with maize residue appears to be the best option in case to avoid cr0p failure. With the high levels of drought stress occurring during the period of water suspension in the on-station experiment, the water-depletion effects overshadowed the SMC-practice effects. Further studies are therefore highly recommended for the investigation of plant responses to drought-stress periods during other growth stages and with different degrees of drought stress. |
| Year | 2004 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. AS-04-09 |
| Type | Dissertation |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Agricultural and Aquatic Systems(AS) |
| Chairperson(s) | Zoebisch, Michael A.; |
| Examination Committee(s) | Ranamukhaarachchi S.L.;Clemente, R.,; |
| Scholarship Donor(s) | Royal Thai Government (RTG); |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2004 |