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Subject: search.filters.subject.Crop irrigation

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    Fruit quality and composition, growth, water relations and postharvest performance of "Braeburn" apples (Malus domestica Borkh.) under reduced irrigation : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Horticultural Science at Massey University
    (Massey University, 1996) Kilili, Anthony W
    Benefits of reduced irrigation in apple production include decreased costs, control of vegetative growth, possible improvement in fruit quality, and reduced leaching of nutrients and pesticides into ground water. This study was on the effects of withholding irrigation at different times of the growing season on water relations, photosynthesis, growth, fruit quality and composition, and postharvest performance of 'Braeburn' apples (Malus domestica Borkh.). Seven-year-old trees on MM. 106 rootstock were subjected to four irrigation treatments in a randomized complete block design. The treatments were: fully watered control (C); early withholding (EW) of irrigation from full bloom until 104 days after full bloom (DAFB); late withholding (LW) of irrigation from 104 DAFB up to final harvest at 194 DAFB; and nonirrigated (NI), where trees were not irrigated during the entire growing season. Trees not receiving irrigation at any stage developed a lower predawn and midday leaf water potential relative to the well-watered control. For LW and NI trees towards the end of the growing season, water stress caused a reduction in the rale of photosynthesis (Pn), stomatal conductance (gs), and the rate of transpiration. The reduction in Pn was caused by non-stomatal factors in addition to a reduction in gs. Withholding irrigation caused an increase in canopy temperature and canopy-air temperature difference in LW and NI possibly due to the reduction in the rate of transpiration. Fruit growth and fruit growth rate measured from 42 DAFB up to harvest were not affected by the treatments although shoot growth and increase in trunk circumference were significantly reduced by withholding irrigation during the early and entire season. Mean fruit weight at harvest and return bloom were reduced in EW and NI relative to C and LW. The treatments had no effect on total yield per tree, crop density or yield efficiency. At final harvest, total soluble solids, soluble sugars (fructose, sucrose, and sorbitol), flesh firmness, and red skin colour intensity were higher in NI and LW than in C. The concentration of glucose and minerals (N, P, Ca2+, Mg2+, and K+) in the fruit was not affected by the treatments. Withholding irrigation during the late and entire growing season resulted in more advanced fruit maturity as indicated by an earlier ethylene climacteric, more yellow background skin colour, and increased total soluble solids concentration. Firmness remained higher in LW and NI than in EW and C during a 12-week storage period at 1 °C. Weight loss was higher in C than in the reduced irrigation treatments. Skin permeance to water vapour was higher in C relative to EW and NI. This study showed that withholding irrigation late in the season may be used in apple production with improved fruit quality in terms of increased total soluble solids, firmness, soluble sugars, and intensified red skin colour without adverse effects on fruit size and yield. For the control of vegetative growth, withholding irrigation early in the season is best but this treatment may adversely affect fruit size. Reduced irrigation is also potentially beneficial in terms of reduced weight loss and increased firmness in storage.
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    Comparison of heritage and modern crop cultivars in response to irrigation and nitrogen management : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Science, Institute of Natural Resources, Massey University, Palmerston North, New Zealand
    (Massey University, 2012) Fandika, Isaac Rhinnexious
    There is a resurgence of interest in heritage crop cultivars (potatoes, squash and yams) in New Zealand because of the premiums farmers get at niche markets. However, a paucity of information in relation to their growth characteristics and resource use efficiency limit successful management of these crops. This research compares the response of different heritage and modern crop cultivars to irrigation, nitrogen (N) fertiliser and canopy management. Some heritage cultivars produced as much marketable yield as modern cultivars while other heritage cultivars had low yields. Modern potatoes were more responsive to irrigation and N than heritage potato crops (collectively known as Taewa). Application of more than 80 kg N ha-1 decreased yield in Taewa (Moe Moe, Tutaekuri) whereas, it increased the yield of modern potatoes (Agria, Moonlight). Full irrigation (FI) increased yield in modern potatoes and Moe Moe. In contrast, Tutaekuri yield was greatest with partial irrigation (PI). FI and 80 kg N ha-1 are recommended for Moe Moe production whereas PI and less than 80 kg N ha-1 are recommended for Tutaekuri. In addition, greater tuber dry matter and low sugar content suggest that Taewa would have better cooking and processing qualities than modern potatoes. Heritage crops required more water than modern crop cultivars because they mature later. There was high ‘water use efficiency’ in heritage pumpkin squash; high ‘irrigation water use efficiency’ in modern potatoes and high ‘economic water productivity’ for heritage potatoes and pumpkin squash. Heritage crop cultivars adapted to water deficit by developing more roots, higher photosynthetic WUE and leaf water potential than modern cultivars. Although total biomass production was similar, heritage crops tended to produce less marketable yield than modern cultivars because of excessive vegetative growth and potato psyllid infestation. Two strategies to manage the canopy and reduce vegetative growth using chlorocholine chloride (CCC) and mechanical topping were developed. Both strategies increased marketable yield in Taewa by 32 - 44%. Application of CCC at 25 and 50 days after emergence (DAE) was recommended for irrigated Taewa, whereas mechanical topping and application of CCC at 25 and 30 DAE were recommended for both irrigated and rain-fed Taewa. The study also observed that potato psyllid need to be controlled up to 170 DAE in Taewa to avoid yield loss equivalent to NZ$10, 485 to NZ$17, 412 per ha. This study contributes to policy on sustainable and improved Maori land use. It can be concluded that premium market prices are important to the success of heritage crops (i.e. to maintain their high ‘economic water productivity’) whereas modern crops might use irrigation water more efficiently (i.e. greater ‘water use efficiency’). It is evident that heritage crops can be grown successfully, and that on occasions they use valuable resources efficiently. To enhance water use efficiency, management of heritage crops should focus on improving the harvest index.
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    Effects of RDI on apple tree (cv. Royal Gala) growth, yield and fruit quality in a humid environment : a thesis presented in partial fulfilment of the requirements for the degree of Doctor in Philosophy in Horticulture at Massey University
    (Massey University, 1990) Durand, Gladys
    The feasibility of using Regulated Deficit Irrigation in the humid environment of New Zealand was evaluated on trees of apple cv. Royal Gala (Malus domestica Borkh.). The study was carried out in a glasshouse experiment and a field experiment. In the glasshouse experiment, it was evaluated the pattern of soil water extraction by the winter mutant of lucerne (Medicago sativa sensu lato) ASR13R from a 'synthetic' soil layered in the same way that it occurs in the research orchard, under trickle and sprinkler irrigation. Results indicated that lucerne extracted soil water at a high rate and explored deep areas of soil. The field experiment was conducted during two consecutive seasons (1987-1989). Lucerne as under tree cover and black polyethylene mulch were compared with conventional herbicide strip to control excess of water in the root zone of the crop that would otherwise promote vegetative growth. These treatments were applied in combination with an irrigation schedule divided into three Phases. In Phase I, water was withheld, in Phase II RDI was compared with full irrigation, and during Phase III which coincided with the rapid fruit growth, all treatments received the full irrigation rate. During the first season, RDI and full irrigation treatments were based on 25% and 100% replacement EPS (evaporation in the planting square) respectively. In the second season, after a 50% of the soil water content in the top 600 mm of soil, between Drainage Upper Limit and me Lower Limit was reached, full irrigation treatments were replenished to the DUL, while RDI treatments received 25% of that amount. Results showed that under the conditions of this study evaluation of crop water requirements based on soil moisture measurements was more reliable than those based on pan evaporation. The degree of reduction of summer pruning obtained under lucerne X RDI treatment, reflected levels of soil and plant water deficit similar to those obtained in arid environments. Results confirmed my hypothesis that by using lucerne as under tree cover, a RDI strategy can be used in this environment. In contrast, black plastic mulch appeared to maintain soil moisture rather than prevent its accumulation. Nevertheless, effects were obtained which reflected positively in fruit growth and yield. Similar results were obtained under the control treatment, although it was less effective for in reducing tree vigour. The latter treatment, however, can be implemented in most orchards at no cost and generate important savings. Apple fruit growth proved to be relatively insensitive to water deficit imposed during early stages of growth, whereas vegetative growth was checked. Restoring full irrigation to coincide with rapid fruit growth stimulated growth of RDI fruits resulting in higher yield under control and plastic X RDI. Lucerne showed higher rates of water use that were not compensated by the irrigation which affected fruit growth and size. Results showed that fruits from RDI treatments were firmer, accumulated higher T.S.S. and had lower bruise susceptibility than fruits from fully irrigated treatments. Fruit quality remained higher after 10 weeks of cool storage.