Crop yield response to water - Cra

There are two types of shoot growth; the above-mentioned preformed or neoformed.All components of a preformed shoot are differentiated in the dormant bud whereas inneoformed growth, some differentiation of its component parts can occur during the growingseason. Most of the buds found on preformed growth are reproductive; there are very fewlateral vegetative buds on preformed shoots. Most of the vegetative growth occurs fromterminal buds. Preformed shoots tend to be short compared with neoformed shoots whichare longer. This longer shoot growth is undesirable because it tends to be weak and hangsdown in the orchard rows, making management and harvest difficult. For these reasons,growers typically remove these shoots on mature trees by pruning during the dormant season.However, long shoot growth may be desirable in young, developing trees to ensure the mostrapid development of the tree canopy.Reproductive bud swelling begins in March. By mid-April, there are 100-300 flowers per rachis.Pollination and fruit set occur at this time. There are generally 20-25 developing fruit perrachis and they grow rapidly, with the hull+shell attaining full size by about mid-May. Thisevent also coincides with a hardening of the shell.Lag phase of reproductive growth: growth Stage IIFrom mid-May through early July, the primary activity in the nut is thickening and hardeningof the shells, a process called lignification. However, dry matter accumulation in the fruitduring this growth phase is low relative to the preceding (Stage I) and succeeding (Stage III)periods. There may also be some additional shoot growth in late May. Reproductive buds thatwill form the following season’s fruit continue to differentiate through June. Sometimes thereis an additional vegetative flush of growth in late June.Rapid kernel development: growth Stage IIIThis phase is characterized by the resumption of a high rate of dry matter accumulationin the nut almost entirely results from the rapid growth of the kernel. Within a matterof a few weeks, the kernel will entirely fill the nut cavity and begin to exert pressure onthe shell. Shell splitting is primarily because of this expansion of the kernel (Polito andPinney, 1999). Shell splitting generally begins in early August. At this time, the hull beginsto breakdown, changing from turgid tissue that is tightly bound to the shell with a papery,loosely connected covering that can easily be peeled from the shell. During Stage III, leaveson the same shoot as developing fruit sometimes become yellow and defoliate. This isthought to be the consequence of translocation of resources from the leaves to the fruit.A certain percentage of the nuts, generally from 10 to 30 percent, do not fill. These are knownas ‘blanks’ or ‘aborted’ nuts. With the former, there is no evidence of any development of theembryo whereas with the latter, the embryo development is aborted. The term ‘blanking’is sometimes used to describe both phenomena. The hulls of these nuts do not breakdownas with the filled nuts. Also they are much more difficult to remove from the tree withmechanical shaking at harvest, resulting in a high percentage remaining on the tree.Harvest is generally from late August to mid-September. Where it is done mechanically byshaking machines, similar to those used for almonds, which remove the nuts. In addition to theshaker, a companion machine, the receiver, is located on the opposite side of the tree and isPISTACHIO 419